title: GPS Elephant Tracking: Utilizing A-GPS, WAAS, DGPS and Understanding HDOP, NSAT, and ZDA

text: *I'm using a GPS data logger (qstarz bt-q1000xt) to track the movement of zoo elephants, and I have a variety of technical questions. I've had limited success receiving answers from the vendor. You can see the GPS anklet on an elephant (links to flickr) here. **A-GPS:**   In mobile phones, A-GPS refers to the ability to use cell towers to triangulate position when SV's are not visible. In GPS units, A-GPS means you can download almanac data via the internet for faster TTFF, rather than downloading the almanac from a satellite. Is this a correct description? If so, does this mean that A-GPS provides only improved TIFF, and has no effect on coordinate accuracy? The reason I ask is that I want to send these units out to other zoos to collect data, but don't want them to have to screw around with the software. **WAAS/DGPS:**   There seems to be varying opinions about whether or not WAAS is a type of DGPS. For example, my data loggers state they have "DGPS(WAAS+EGNOS+MSAS) support." Yet my understanding is that WAAS is an SBAS that my device can access and utilize in real time, and DGPS is an GBAS which is strictly a post- processing analysis done with software. But perhaps this is wrong, and you can purchase fancy receivers that allow your unit to execute differential correction in real time? Even if this is true, for budgetary reasons I am more interested in post-processing with DGPS. What level of expertise is required to conduct DGPS analysis? Where would be a good place to start looking for more information on this? The reason I ask is that I hope to evaluate elephant herd dynamics, for which I need meter or sub-meter accuracy, which my data logger alone cannot seem to provide. **HDOP/NSAT:**   Zoo researchers using GPS regularly remove fixes with an HDOP less than 2, and will then also remove fixes with an NSAT less than 6, "just to be safe." However, 4 satellites with perfect geometry should be able to make a highly accurate fix. Is there any reason to remove fixes with NSATS of 4 or 5? I also understand that an HDOP value of 1 is "perfect;" meaning the satellite geometry is multiplying the effect of other errors (atmospheric effects, satellite clock error, etc) by a factor of 1 (i.e., not at all). But my data loggers occasionally give an HDOP value of less than one. How can this value be interpreted? **ZDA:**   Are the times provided by this NMEA sentence more accurate somehow than the times given by RMC? Why would you want to record ZDA? An associate told me that the irony of GPS is that everyone knows enough to be dangerous, but nobody REALLY knows how it works. Prove him wrong? Thanks!   Matty ![enter image description here](http://i.stack.imgur.com/8xd2P.jpg) ![enter image description here](http://i.stack.imgur.com/Zp3yN.jpg)


title: I am getting a blank layer preview from geoserver after Quick Exporting my shapefile to postgis and then getting postgis to point to geoserver

text: What could be the potential problems? Looking at the layer's data fields/form the one thing that isn't filled is the Native SRS and its source, but I have already passed in the projection info as it shows up as a source for the EPSG. So why wouldn't it be showing up? My formatting is right. By the way, I'm stating this in a general sense because I'm doing this programmatically using a python script, but unfortunately I haven't seen any instances of anybody doing the same.


title: ST_Covers: Geography Implementation is not working, Geometry Implementation taking too long

text: I have a query: (This query uses geographical implementation of ST_Covers function)               SELECT ST_Covers(ST_GeoGraphyFromText('MULTIPOLYGON(((179 -89,179 89,-179 89,-179 -89,179 -89)))'),ST_GeographyFromText('POINT(20 30)'));      When I run this query it **should return true but it returns false.** I don't know whats wrong with PostGIS (or with this query). When I change the geographical implementation with geometrical one, and **rearrange the query to be like below:**               SELECT ST_Covers(ST_ASTEXT(ST_GeoGraphyFromText('MULTIPOLYGON(((179 -89,179 89,-179 89,-179 -89,179 -89)))')),text('POINT(20 30)'));      **This query works as it should, returning true:** I can use this query to be content but the problem is when database is large it takes too much time. Can someone tell me   1. how to make query 1 to work right (as intended, returning true)? or    2. how to make query 2 work fast with large tables?  (please do not suggest that i should remove `ST_GeoGraphyFromText('MULTIPOLYGON(((179 -89,179 89,-179 89,-179 -89,179 -89)` because it only represents geographical data that will be replaced by data from the column of table ) Other values which fail with query 1, are (5 5) (10 10) (-10 -10) (and many more)


title: ArcGIS Model Builder - Loading Tab Reader Parameter

text: In our office, we got a large set of MapInfo TAB files, and are planning to migrate those data to ArcGIS GDB with the same symbology available in the TAB file. On a individual TAB file to GDB, we can do it like:   * Import data from TAB A to GDB A using Data Interoperability, by its corresponding CRS.   * Then adding GDB A's featureclass to ArcMap and "load symbology from TAB file" using TAB Reader though unique data   * Then save applied symbology to ".lyr" file or converting them to "Representation". The following figure explain the workflow, not the model builder. ![enter image description here](http://i.stack.imgur.com/LnGWa.jpg) To convert hundreds of TAB files is taking a lot of time. So, I thought of doing with coding or model builder. Since I am very poor with Python or any other coding, I am going with model builder. The problem arises when I tried to load symbology from TAB file. Could any one help me out in this regard?


title: Benefits of using GIS in business intelligence software?

text: Business intelligence softwares use a lot of data in order to create reports helping decision makers. Given that more and more GIS resources and services are available and that data can often be located in space, the geographic dimension of data can bring useful insights when analyzing data. Rendering geocoded data on thematic maps is the simplest and most obvious application of using GIS in BI software. What are the other ways to benefit from GIS in business intelligence? What kind of resources or methods could be used to improve the usefulness of maps when making business-specific decisions? What are the already existing products in this domain?


title: Need to create a collection of polygons from a collection of points

text: I have a set of points, which are spread over a wide geographical area. I need to be able to create a set of polygons which best represent the clustered points. In parts, some points may simply lie on their own, but in the main they are grouped, but not linked. I have effectively created a grid of, lets say, the north western hemisphere and in each grid, have created a point with an arbitrary value. For all values of zero, I have deleted the points, leaving the points with non zero values in them. I now need to turn these points into polygons and am struggling a little... Using ArcGIS and python, I thought about clustering the points, then 'convex hulling' them, but am struggling through not really knowing ArcGIS that well; how do I cluster? thanks in advance for any help.


title: How to extract features from a vector layer?

text: I have a vector file containing the river lines of an area. I want to extract a specific water line from the vector. I used: `v.db.select` but it only displayed:                  cat|F_CODE_DES|HYC_DESCRI|NAM|ISO|NAME_0         1|River/Stream|Perennial/Permanent|UNK|PHL|Philippines         2|River/Stream|Perennial/Permanent|UNK|PHL|Philippines         3|River/Stream|Perennial/Permanent|UNK|PHL|Philippines     ...      then i used `v.extract` to select a specific area and it displayed this error:               v.extract input=vector_waterLines@PERMANENT output=vector_1 where=1                  DBMI-DBF driver error:     ERROR: Unable select records from table <vector_waterLines>


title: gvSIG advantages

text: Direct comparison between software may not be the best thing to do but as I can't arrive at a conclusion thought of asking here. Is there any gvSIG user in this GIS community? Looking at the screenshots gvSIG seems to have lot of features. I particularly liked the single window interface when compared to GRASS. So I wanted to know how gvSIG would suit for image processing and GIS operations in general. How are the map composing features in gvSIG? I would also like to know which fares better amongst gvSIG or GRASS for image classification task - particularly digitizing training sites which is improving in GRASS these days(even then working with QGIS is easy for the purpose), ability to handle large rasters and vectors in the process, ease of map composing etc.


title: How to enable projection transformation in QGIS

text: My QGIS project has two layers, one layer is retrieved by Google layer plugin which fetches the static Google map image whose CRS is +proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +units=m +no_defs and another vector layer is a postgis layer whose CRS is +proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs. I digitalized some polygon features from Google Layers and added it to the vector layer. However, QGIS seems do not make the automatic CRS transformation. How can I change its projection? Thanks


title: Importing ERDAS-processed GTOP030 dem data into ARCGIS

text: I have two GTOP030 DEM images. After downloading them, I have imported into ERDAS and mosaiced them. Then I have exported it to .tif file in order to open it in ARCGIS. But when I tried to open it in ARCGIS, "the memory could not be 'read'" error message appeared on the screan and turned off ARCGIS. what's wrong with this. Do you have any idea for this? Another thing I ask from you is how to remove No data value from this DEM file because min value of this DEM image is -9999. Many thanks


title: How to extract values of one point dataset to second point dataset based on proximity using R?

text: I have to point shapefiles and would like to extract values from one point shapefile to another one based on some measure of proximity, i.e. for any given point in dataset x, extract the mean value for all points in dataset y within a 10km radius of the given point in dataset x. Or, for any given point in x, extract the value of the closest point in y and add to x. I'm familiar with extract function in r to extract raster values to point. Not sure if sample data would help in this one, but would like to do this in r, or failing that, ArcGis. Your help and patience are greatly appreciated!


title: cut off part of catchment

text: I want to edit a polygon as that I cut off a part of it. I want to freely make a line that define where the polygon should be seperated. I have tried to useedit vertices but it does not seem to be a good tool for the purpose. I use ArcGis 10.1


title: How much database bloat is reasonable?

text: I use personal geodatabases to hold all the data for my projects (probably around 10-20 feature classes across 2-4 datasets on average). I use the personal gdb because I like being able to hook into it through other MS Office products and use mail-merge for reports and access for pivot tables etc etc. Also, ArcGIS 10.1, Windows 7, data located on a network drive. Over the last few months I have been automating all my boring tasks using arcpy and am noticing some substantial bloat in my databases after I run certain tools (from a python toolbox, not esri stock tools). For instance, this morning I ran the script that iterates through each polygon in a feature class, selects all the features that are inside of them, sums their [COUNT] fields and then uses CalculateField_management tool to write that sum to a field in the polygon attribute table. There are roughly 2500 records in the polygon field, so about 2500 iterations, selecting 1-5 records from 6-7 feature classes during each iteration. When the operation completed, my gdb had bloated up to 2.0 GB (yes, the magic 'now nothing will work' number). After I ran a simple 'Compress Database' in arcCatalog the size dropped to 32MB. That's a decrease of 98.5 percent, which seems egregiously huge. So, my question is: **_Is that a normal amount of shrink/swell for a personal geodatabase or am I doing something wrong?_** Further, if I am doing something wrong, what strategies can I employ to fix it? Would there be significant performance benefits to using a file geodatabase instead of a personal? Lastly, I am becoming increasingly aware that the bulk of what I am doing in arcpy could be more easily accomplished using SQL in a more robust database environment... Is it time to take the plunge and start learning about postgresql? As always, any help/advice/constructive criticism/epiphany laden comments are appreciated.


title: How to import or incorporate formated Excel tab into QGIS print composer

text: I would like to know if there's a way to import formated Excel Tab into QGIS print composer. Below is an attachment of formatted Excel tab example I has been asked to display on qgis map composer. Regards! ![formatted Excel tab example](http://i.stack.imgur.com/Ami0C.png)


title: InsertFeature on a versioned layer [vba]

text: I am writing an application that takes data from an Excel Spreadsheet and loads it into an ArcSDE feature class. The Feature class is editable within ArcMap, but I am having trouble inserting a feature with the code. My code does the following   1. Starts an edit session.              Public Sub StartEditing(fctarget)          Dim peditor As IEditor     Dim pID    As New UID     Dim pFeatureLayer As IFeatureLayer     Dim pDataset As IDataset     Dim pMap   As IMap     Dim pmxdoc As IMxDocument     Dim LayerCount As Integer     Set pmxdoc = Application.Document     Set pMap = pmxdoc.FocusMap     pID = "esriEditor.Editor"     Set peditor = Application.FindExtensionByCLSID(pID)          If peditor.EditState = esriStateEditing Then Exit Sub          'Start editing the workspace of teh feature layer     Set pDataset = fctarget     MsgBox "Editing: " & pDataset.BrowseName     peditor.StartEditing pDataset.Workspace          peditor.StartOperation          End Sub        2. Load the data (if it is a new record, the following code runs)                If pfeatLayer Is Nothing Then    'if it does not exist - it is new            'Insert a new record and add new attribute information       Set pFeatInsertBuf.Shape = pFeat.Shape       Debug.Print pFeatInsertBuf.Shape.envelope.XMax       xField = pFeatInsertBuf.Fields.FindFieldByAliasName("ORIG_X")       yField = pFeatInsertBuf.Fields.FindFieldByAliasName("ORIG_Y")            pFeatInsertBuf.Value(xField) = pFeat.extent.XMax       pFeatInsertBuf.Value(yField) = pFeat.extent.YMax              'Update the attributes       For C = 1 To NumberOfFields             If IsNull(pExcelApp.Cells(r, C).Value) Then                 pFeatInsertBuf.Value(C).Value = ""             Else                 pFeatInsertBuf.Value(C) = pExcelApp.Cells(r, C).Value             End If      Next C      Debug.Print pFeatInsertBuf.Fields.FieldCount      Debug.Print pFeatInsertBuf.Value(2)      Debug.Print pFeatInsertCur.Fields.FieldCount      'store the record      pFeatInsertCur.InsertFeature pFeatInsertBuf ' #######INSERT THE FEATURE######      Print #1, "Row number " & r & ": " & "inserted"      Debug.Print "Row number " & r & ": " & "inserted"        3. When it has gone through the rest of the spreadsheet, the stop editing process is called and the editor session is closed.              Public Sub stopSaveEdits(step As String)          Dim lngCityDevRefVal As Long          Dim peditor As IEditor     Dim pID    As New UID     Dim lngSave As Integer     Dim pMap   As IMap     Dim pmxdoc As IMxDocument     ' get the current map document and create and editor object     Set pmxdoc = ThisDocument     Set pMap = pmxdoc.FocusMap     pID = "esriEditor.Editor"     Set peditor = Application.FindExtensionByCLSID(pID)     'step = "Save"     If peditor.EditState = esriStateEditing Then         'lngSave = MsgBox("Do you want to save?", vbYesNo, "Save data")         If step = "Save" Then             peditor.StopOperation "Saving..."             Exit Sub         ElseIf step = "SaveStop" Then             peditor.StopOperation "Saving..."                  If peditor.HasEdits = True Then                 peditor.StopEditing True                 'MsgBox "Changes have been saved"                      Exit Sub             End If         Else             peditor.AbortOperation             'peditor.StopOperation "Saving..."             peditor.StopEditing False             MsgBox "Changes have not been saved"         End If     End If          End Sub      The problem is that the new feature never gets inserted, even though i have specified to do it. Has anyone got any ideas on what I am doing wrong? Note - Using ArcGIS Desktop 9.3.1, ArcSDE is 9.2 Thanks!


title: Tilestache/Mapnik: Is it possible to create dynamically filtered layers?

text: I'm using Tilestache to generate two layers with the `mapnik` and `mapnik grid` providers, and it's working great! However, I want users to be able to filter the data over many (more than ten) dimensions, and only show the features that match the user's filters. Creating a `mapnik` and `mapnik grid` layer for each of these dimensions--and each new one that comes up--seems like the wrong way to do this. And there are too many features to simply use GeoJSON. So, is there a way to do this filtering dynamically? Intuitively, I'd like to pass parameters via GET request to Tilestache, which then passes the parameters along to the layers' providers, which tweak their queries. Or am I thinking about this in entirely the wrong way?


title: Measuring Script Writing Competency

text: I've been asked by my manager to come up with some sort of competency measure for an employees understanding of scripting/programming. Because I am a self taught programmer, I really don't have a formal understanding of how to measure ones level of understanding when it comes to script writing. We have been using Python in ArcGIS and QGIS. We use VB.Net with our MS Office products and we have started to dabble in Java for web mapping. I'm wondering if any of you GIS managers out there have some sort of matrix/method to determine your employees skill level when it comes to scripting. Thanks, Mike


title: Python is only using one core at a time to work

text: I noticed recently that python is only using one core at a time to work. Is there a way, maybe special builds or commands, to make it use all resources (second core)?


title: Can I set the max or min zoom on a CartoDB embed?

text: I'm using the default iframe embed to display two CartoDB maps, but I'd like to prevent people from zooming out past a certain point, or if that isn't possible, to prevent zooming at all. Can I do that? I sniffed around but I don't see anything obvious. I tried adding `&maxzoom=5` to the URL, but that doesn't seem to do anything.


title: Convert 3-band raster imagery to distinct vector zones in ArcGIS

text: So much like the title says I would like to convert a 3-band infrared image TIF file of vegetation into distinct vector feature zones using ArcGIS. I'm guessing the only way to do this is with Spatial Analyst extension which is fine. The result goal would be having a feature class that would have polygon features of different vegetation levels based on the original raster image. Basically I don't want to have to hand draw my own polygon features by using the raster image as a base layer. Steps and tools involved would be appreciated.


title: Connect to Postgresql ArcSDE 10.1

text: I cannot connect to postgresql 9.0.5 with ArcSDE 10.1, using ArcCatalog 10.1 on Win 7 professional 64 bit. I followed the steps described here, and installed the Pg-Agent from Stack builder. When I execute "Create Enterprise Geodatabase", I set "instance" to "localhost:5432", but I got this error:               Cannot connect to database because the database client software failed to load.  Be sure the database client software is installed and configured correctly.     Failed to execute (CreateEnterpriseGeodatabase).      I've made sure that the service is running and restarted the whole machine after these installations, but it still gives me the error. Any help, please?


title: Reading GeoTiff using .NET

text: Is there a managed library for reading the coordinates from a geotiff file in .NET ? I know it can be done thru GDAL, but I am looking for a **managed** alternative.


title: Nearest Neighbor Grouped Selection in QGIS

text: OK - so I have an interesting problem I am trying to solve. I have a list containing over 100,000 points in lat/long format which I have imported into qgis. Now, what I am trying to do here is group all of these points into box groups and by that I essentially mean that I want to split up the map into bounding boxes. My requirements are are follows:   * no boxed group should have LESS THAN 100 and NO MORE THAN 200 points   * no point should be located in more than one group   * all points should be be based on their nearest neighbor My question is... how could I achieve this through qgis? I am assuming that one can pass some custom query code and save the results or the boxes created as a shapefile correct? Could someone please explain how this could be done and what the code would look like? As mentioned, my objective is to have a bunch of square boxes displayed as a shapefile layer where within each box there are no less than 100 properties and no more than 200. Thanks guys


title: Error while importing shapefile using shp2pgsql: Coordinate values are out of range

text: I have a shapefile with 180 points. I'm using shp2pgsql-gui via pgAdminIII. This is an error it gives me when I try to import shapefile.               Failed in pgui_exec(): ERROR:  Coordinate values are out of range [-180 -90, 180 90] for GEOGRAPHY type      This is information about coordinate system:               Geographic Coordinate System:   GCS_WGS_1984     Datum:  D_WGS_1984     Prime Meridian:     Greenwich     Angular Unit:   Degree      Can someone help me?


title: Display map scale (like 1:20.000) next to ScaleBar

text: In my PageLayoutControl I add a ScaleBar. Additionaly I like to show the map scale/ratio (e.g. "1:20.000") next to it, but didn't find a way to achieve this with the ScaleBar. Am I missing something or is there another way to do this? Here is, how I add the ScaleBar:                 IEnvelope envelope = new EnvelopeClass();       envelope.PutCoords(5, 0.1, 12.4, 1); // Specify the location and size of the scalebar       IUID uid = new UIDClass();       uid.Value = "esriCarto.ScaleLine";            // Create a Surround. Set the geometry of the MapSurroundFrame to give it a location       // Activate it and add it to the PageLayout's graphics container       IGraphicsContainer graphicsContainer = pageLayout as IGraphicsContainer;       IActiveView activeView = pageLayout as IActiveView;       IFrameElement frameElement = graphicsContainer.FindFrame(map);       IMapFrame mapFrame = frameElement as IMapFrame;       IMapSurroundFrame mapSurroundFrame = mapFrame.CreateSurroundFrame(uid as UID, null);       IElement element = mapSurroundFrame as IElement;       element.Geometry = envelope;       element.Activate(activeView.ScreenDisplay);       graphicsContainer.AddElement(element, 0);       IMapSurround mapSurround = mapSurroundFrame.MapSurround;            IScaleBar markerScaleBar = (IScaleBar)mapSurround;       markerScaleBar.LabelPosition = esriVertPosEnum.esriBelow;       markerScaleBar.UseMapSettings();


title: Identifying when a value in a field changes from 0 to 1

text: I am trying to identify the start and stop of a particular incident- these are indicated by the unique values 0,1,2,3,4,5,6. 0 represents no incident- therefore in order to identify when an incident starts and stops and only retrieve these data records (i.e. incident 1) I would like to know how to query or determine when the value in the incident field changes from a 0 to a 1 (i.e. the start) and query when the value changes from a 1 to a 0 i.e. the finish. I only want to compare these changes between adjacent records i.e. those either side of a record. Any help would be appreciated Thanks


title: How does OpenLayers determine a layer's projection?

text: Could anyone explain the strategy OpenLayers take to determine the layer's projection? For example, if I didn't explicitly specify any projection for a marker layer, what projection would the layer take?


title: How can we use SQL to update feature class attributes in a versioned geodatabase in ArcGIS Workgroup

text: ArcGIS Workgroup Edition 9.3.1, MS SQL 2005 Express I have some attribute data that I want to periodically update with information from another RDBMS using SQL UPDATE commands. The data is versioned and we were planning on creating a "sql-updates" version just for this purpose, since others have said that doing this in the default version is not a good practice. Is this possible and what would be the general or best method of doing it? One possibility would be using these stored procedures: set_current_version, edit_version (1 - start session), run my updates, and edit_version (2 - close session). I don't know if this is the correct way, and if delta tables get entries used for reconcilliation with the other versions. Note that "sdetable" is not available with Workgroup edition. Another possibliity would be creating a separate table for this data, then joining the data with the feature class data, which would allow direct SQL updates to the separate table.


title: Overlaying lat/lon points on Google layer in OpenLayers

text: I'm stuck adding a vector point in lat/lon on top of a Google layer in OpenLayers. The point is moving when I pan the map. This doesn't happen if I replace the Google layer with a layer in WGS84. How can I fix this?               map = new OpenLayers.Map('map');     map.addControl(new OpenLayers.Control.LayerSwitcher());          var gmap = new OpenLayers.Layer.Google(                 "Google Streets",                  {numZoomLevels: 20}                );     var pointLayer = new OpenLayers.Layer.Vector("Point Layer");          map.addLayers([gmap,pointLayer]);     map.setCenter(new OpenLayers.LonLat(16.373056, 48.208333), 5);          var point = new OpenLayers.Geometry.Point(16.373056, 48.208333);     var pointFeature = new OpenLayers.Feature.Vector(point,null,null);     pointLayer.addFeatures([pointFeature]);      I've tried to follow http://docs.openlayers.org/library/spherical_mercator.html but without success.


title: Can an htm file be imported into Trimble's Data Dictionary Editor?

text:
We've received several data dictionary files from other entities and they all are in *.htm format. We were hoping to not reinvent the wheel, as these are massive data dictionaries, so does anyone know if there is any way to import these files into Trimble's Pathfinder Office data dictionary editor? This is from more than one entity, so it made me wonder if there's something I'm missing or didn't know about htm files and data dictionary files. Thank you in advance. Here's a snippet of the htm file, I cut out several
 and
:
Attribute_Label:  PostSystem

Attribute_Definition:  Sign post system.

Attribute_Definition_Source:  GIS/BCPWD

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value:  Other

Enumerated_Domain_Value_Definition:  Other

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value:  Round

Enumerated_Domain_Value_Definition:  Round

Attribute_Domain_Values:

Enumerated_Domain:
Enumerated_Domain_Value:  Telespar

Enumerated_Domain_Value_Definition:  Telespar

Attribute:

Attribute_Label:  PostSupport

Attribute_Definition:  Sign post support.

Attribute_Definition_Source:  GIS/BCPWD

Attribute_Domain_Values:


title: How to use the same client for Oracle 8 and Oracle 11g?

text: I have a legacy system into Oracle 8, and spatial database in Oracle 11g. When I installed the Instant Client for Oracle Spatial access to Oracle 8 did not work. My question is how can I do to be able to access two databases with the same client without versioning conflicts.


title: Convert geometry to latitude-longitude using PostGIS ST_Transform

text: My table has a geometric field, in EPSG:3857, of type point. I need the latitude and longitude, in EPSG: 4326, of each point. Could someone give me a valid example of how to use ST_Transform().


title: How to create polygons from unclosed polylines?

text: I have a layer of driveway that is in polylines _unclosed_ . They are just two parallel lines outlining the width of the driveway. Then again, there is a gap (sidewalk layer) and driveway continues until it touches the road. So my question is how to extend the line? and how to close all those lines to form a polygon? I also have a lot boundary that has a unique ID. So I can summarize the lines that fall within the same boundary ID. But I am encountering the problem to connect the lines and make it a polygon layer. ![enter image description here](http://i.stack.imgur.com/vuEZc.png)


title: How to extract data using arcpy.da.SearchCursor

text: I have a shapefile of point features showing fire locations in a given year. One of the fields is named "YYYYMMDD" and indicates the corresponding date that that fire happened. In Python, I am trying to use the arcpy.da.SearchCursor function to append each date into a list and find the most recent fire by date. My code looks like this:               listname = []     cursor = arcpy.da.SearchCursor(fires, "YYYYMMDD")          for row in cursor:         listname.append(row)          print 'the first fire date is ',min(listname),'.'     print 'the last fire date is ',max(listname),'.'      What prints for min and max listname is: (20010515.0,) and (20011002.0,) But what I would like to get as an output is: 20010514 and 20011002 How do can I get that as my output? I tried indexing what I got to exclude what I don't need but that doesn't work. Any help would be greatly appreciated!


title: Is there a way to add an autoincrementing primary key field to an existing spatialite table/layer?

text: I know that I can add a new column to a spatialite table either through the Database Manager (Edit Table – Add Column) or through the Attribute Table – Field Calculator (create new field) but I don´t know which settings to use there to get a new column populating itself with an autoincrementing primary key. I guess it must be possible... I also have the Plugins Table Manager and QSpatialite installed. Thanks for reading, appreciate any help (QGIS Beginner)


title: Python Window Crash and import arcpy issue

text: Trying to do anything in the Python shell within ArcGIS 10.2 and it just crashes once I hit enter after writing code, no matter what I do. I've tried to uninstall, deauthorize, reinstall, re-authorize, hoping it would repair, but it still crashes. On a similar note (not sure if they're connected), I can not import arcpy outside of ArcGIS, whether it's in the 2.7.3 shell or WING IDE. It prompts that: > raise TypeError("This object does not support enumeration") > > TypeError: This object does not support enumeration I don't understand any of this, I've always had an issue trying to import arcpy, I don't get it. I thought it was as simple as updating the Python paths to the arcpy library. Any help or suggestions? Here's the result of sys.path: > ['', 'c:\Program Files (x86)\ArcGIS\Desktop10.2\arcpy', 'C:\', 'c:\Program > Files (x86)\ArcGIS\Desktop10.2\arcpy\arcpy\gdal', > 'C:\WINDOWS\SYSTEM32\python27.zip', 'c:\Python27\ArcGIS10.2\DLLs', > 'c:\Python27\ArcGIS10.2\lib', 'c:\Python27\ArcGIS10.2\lib\plat-win', > 'c:\Python27\ArcGIS10.2\lib\lib-tk', 'c:\Python27\ArcGIS10.2', > 'c:\Python27\ArcGIS10.2\lib\site-packages', 'C:\Program Files > (x86)\ArcGIS\Desktop10.2\bin', 'C:\Program Files > (x86)\ArcGIS\Desktop10.2\ArcToolbox\Scripts', > 'c:\Python27\ArcGIS10.2\lib\site-packages\win32', > 'c:\Python27\ArcGIS10.2\lib\site-packages\win32\lib', > 'c:\Python27\ArcGIS10.2\lib\site-packages\Pythonwin']


title: Stuck in loading raster to PostGIS

text: I am running running Mac OS X (10.7.5), PostgreSQL (9.2) and PostGIS (2.0.2) (installed via Postgres.app). The PostGIS extension seems to work perfectly with vector and raster layers. Once I enable PostGIS for the specific database I am able to create vector and rasters from the SQL Editor of phpAdmin3 (like with ST_MakeEmptyRaster). The problems begin when I try to load a raster with raster2pgsql. I have no great experience with Postgres (or DBMS in general) so what I did might appear stupid... I tried to launch it via psql following this steps: 1) Open psql terminal; 2) typed `\c mydatabase`; 3) Got as prompt `mydatabase=#` (that I guess means I am logged with owner rights...; 4) Now I tried `raster2pgsql -G`but of course is no SQL so I got `ERROR: syntax error at or near "raster2pgsql" LINE 1: raster2pgsql -G;` Then I went back to my Mac OS X terminal shell and into the the folder where my raster2pgsql file is located (/usr/local/pgsql/bin) and typed `raster2pgsql -s 4236 -I -C -M *.tif -F -t 100x100 /my/path/to/the/file/myfile.tif myrastertable | psql -U myuser -d mydb -h localhost -p 5432` but I got `-bash: raster2pgsql: command not found`. What I am doing wrong?


title: Are there any Python scripts for creating .mxd files?

text: I am a newbie to both ArcGIS and Python. My requirement is to automate the below MANUAL process:   1. Creating a layer in ArcGIS for Desktop. To put it in another words, creating an ArcMap document (.mxd).   2. Publishing the created ArcMap document (in Step 1) as a service to ArcServer. Currently we are doing this manually. I have come across scripts to automate step 2 using Python. Any guidance to automate step 1 and step 2 would be great.


title: How do map providers collect/update street names in the Middle East?

text: Lets talk about middle east countries, which are not as fully covered as European countries and the US. How do map providers get street names, update new areas and all of these related things? Do they have agent or stuff to provides them with the data ?


title: How I get dbflib module for python27

text: I'm trying to use a script by python to download MODIS imagery. I follow this script: http://pyevolve.sourceforge.net/wordpress/wp- content/uploads/2009/02/modis.py. I installed: > matplotlib-1.3.1.win32-py2.7.exe basemap-1.0.7.win32-py2.7.exe But I can not run this script. It has an Error: > ImportError: No module named dbflib I try to google search dbflib module. There are two file dbflib.py: https://code.google.com/p/geoyard/source/browse/trunk/pyshapelib-0.3.1/dbflib.py?r=5 and: http://liulele84-le.googlecode.com/hg/src/python/_basemap/PLATLIB/dbflib/dbflib.py But it does not work. Does have anybody know how to fix this problem? Help me, please. Thanks so much.


title: How do I convert to EPSG:3857 with GDAL?

text: I have some TIFs in EPSG4326 the GeoTiff info looks like:               GEOGCS["WGS 84",         DATUM["WGS_1984",             SPHEROID["WGS 84",6378137,298.257223563,                 AUTHORITY["EPSG","7030"]],             AUTHORITY["EPSG","6326"]],         PRIMEM["Greenwich",0],         UNIT["degree",0.0174532925199433],         AUTHORITY["EPSG","4326"]]      How do convert them into EPSG:3857 so that the GeoTiff info reads something like:               PROJCS["Google Maps Global Mercator",         GEOGCS["WGS 84",             DATUM["WGS_1984",                 SPHEROID["WGS 84",6378137,298.257223563,                     AUTHORITY["EPSG","7030"]],                 AUTHORITY["EPSG","6326"]],             PRIMEM["Greenwich",0],             UNIT["degree",0.0174532925199433],             AUTHORITY["EPSG","4326"]],         PROJECTION["Mercator_1SP"],         PARAMETER["central_meridian",0],         PARAMETER["scale_factor",1],         PARAMETER["false_easting",0],         PARAMETER["false_northing",0],         UNIT["metre",1,             AUTHORITY["EPSG","9001"]]]


title: Is there any experience using Computer Games to display GIS data?

text: besides being a GIS use I'm a big computer game fan.   Games like Civilization, Minecraft, World at War and many others have a very powerfull engine to display huge maps in a beutifull way. I was wondering if there is any experience in using game engines to display GIS data for a better comprehension or visualization of the environment?


title: Trimble GeoXH vs GeoXT and GPS Correct

text: I am about to purchase a new GPS unit. I currently have a GeoXT and have used the combo of GPS Correct/ArcPad with GPS Analyst/ArcMap to correct the collected data to submeter (or close to it). Looking at the GeoXH specs, it will already collect data at submeter. So if I use GPS Correct with a GeoXH, how much more accurate will it be? Will it just verify that my data has been collected at submeter accuracy or will it get corrected down to like subfoot accuracy or something? I'm not familiar with technical details of GPS units, but was wondering if the upgrade to a GeoXH is worth the added cost?


title: Displaying operational layers in the overview map

text: Does anyone have the code to display an operational layer within the overview map?


title: How to list feature classes with active "attribute domains"?

text: I have an Esri file geodatabase with attribute domains defined. I need to delete some of the attribute domains but can't because _"The domain is used by an attribute rule."_. How might I discover which feature class(es) are using the domains?               Executing: DeleteDomain R:\v5\YT_Canvec.gdb Permanency     Start Time: Thu May 19 11:01:02 2011     ERROR 999999: Error executing function.     The domain is used by an attribute rule.     Failed to execute (DeleteDomain).     Failed at Thu May 19 11:01:02 2011 (Elapsed Time: 0.00 seconds)      There are over a hundred feature classes in the geodatabase, interactively looking at the FC field properties for each one is a non-starter. The gdb is too large to convert to a personal gdb and go in the back door with ms-access (a dodgy method anyway). * * * _(2011-May-26):_ Another way to phrase this is "which Feature Class is using domain X?"


title: OpenLayers GeoJSON Data Store

text: **Background** : I have a single geoJSON data object that backs multiple Vector Layers of its features. I do this because the feature data has many attributes and can be presented in many different ways, and by having multiple layers, I can quickly switch between visualizations. My issue comes into play when I update the data in the corresponding backing- data store. Since the features were only loaded once (Strategy.fixed), they do not see the updates to the underlying store, and instead retain the properties they were initially loaded with. I was hoping there was a _strategy_ or _eventing mechanism_ already created that I can alert my layers that it's underlying data has changed and to refresh it's features as required. As of now, I have to either a) update each feature in each of my layers and then redraw those that changed or b) remove and add all the features on each of my layers for them to see the changes. I imagine that the Refresh strategy could somehow be of assistance, but that would bring it's own issues (namely intervals instead of instant updates and the need more for more than just inline geojson object declarations). Thanks for any help or suggestions.


title: Where are the address ranges in Open Street Map?

text: I recall coming across some OSM initiative that was proposing to put US address ranges in the data using TIGER (I think). However, I have seen no such ranges in any of the data I have looked at so far. I am wondering if anyone has noticed this kind of information or can point me in the direction of concrete descriptions of its existence (or lack thereof). If it does not exist, is there a method for extracting address ranges from what is given in nodes and ways? I know the data can be very spotty, but assuming a perfect world of open source data editing, if a way is comprised of nodes that each have an address, could one extrapolate To-From address ranges for the left and right side of the line?


title: Measure the area of a polygon resulting from the intersection of two other polygons?

text: How can I measure the area of a polygon resulting from the intersection of two other polygons? If I use the measure tool or open the attribute table for the resulting polygon, it shows me the areas of the original two polygons...


title: ENVI raster file with nodata change to 0

text: I have a geotiff that I converted to a ENVI raster file with the following command: > gdal_translate -of ENVI srtm_05_08.tif data.bil The geotiff has water values supposedly set to nodata. I am doing an interpolation on the data.bil file, and when I do, the water shows up at a height of about 32000m. I am wondering if there is a simple way to change the nodata to be 0. I tried: > gdal_translate -of ENVI srtm_05_08.tif data.bil -a_nodata none and > gdal_translate -of ENVI srtm_05_08.tif data.bil -a_nodata 0.0 but neither of those seemed to work. Is there an easy way to switch the data values? I could do something like: _if (val>5000) then val=0_ but I am very much a beginner and don't know how to do it.


title: How to simulate events from Openlayers 2?

text: I am working on a GIS API that uses OpenLayers. I am testing it using QUnit. The problem is I need to simulate clicks and trigger some events to be able to test the whole code. For example, I have a feature to draw a polygon and I want to just trigger the "featureadded" event. Is it possible to trigger OpenLayers events without actually working graphically? Thanks


title: Tools for importing historical maps into modern GIS systems

text: What tools exist to derive geometries for use with modern GIS systems from older scanned maps? I am referring more to libraries that generate actual data rather than present an interface for manually editing or tracing features. If no such tools exist, are there any academic papers or research (or shameless hacks!) from related fields that might shed light on the problem?


title: Union of several linestring to multilinestring using MS SQL Server

text: Followed Postgreql query is the existing one used to combine serveral linestring to a single multilinestring. is there any equivalent of this in SQLServer .               SELECT ST_AsText(ST_Collect(          ARRAY[          ST_GeomFromText('LINESTRING(1 2, 3 4)'),                     ST_GeomFromText('LINESTRING(3 4, 4 5)')     ]     )) As wktcollect;      This is the sample query . My input will be multiples of Linestrings . (Eg: LINESTRING(1 2, 3 4)) which comes dynamically . Kindly execute this in Postgresql . you will get a clubbed Linestrings as single MultiLinestrings . Same result required in SQL server . Kindly Help me in this .


title: Labels not visible at same zoom range

text: I am using geoserver and sld : I want to make all labels visible at all zoom levels. How can I do that with SLD?               <?xml version="1.0" encoding="ISO-8859-1"?>     <StyledLayerDescriptor version="1.0.0"          xsi:schemaLocation="http://www.opengis.net/sld StyledLayerDescriptor.xsd"          xmlns="http://www.opengis.net/sld"          xmlns:ogc="http://www.opengis.net/ogc"          xmlns:xlink="http://www.w3.org/1999/xlink"          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">       <NamedLayer>         <Name>Attribute-based polygon</Name>         <UserStyle>           <Title>HAPPY FACE</Title>           <FeatureTypeStyle>           <Rule>             <Name>min</Name>             <Title>Data Unavailable</Title>               <ogc:Filter>                              <ogc:PropertyIsLessThan>                     <ogc:PropertyName>PS_GPRS_to_WCDMA_HOSR</ogc:PropertyName>                     <ogc:Literal>0</ogc:Literal>                   </ogc:PropertyIsLessThan>                        </ogc:Filter>              <PolygonSymbolizer>                <Stroke>                  <CssParameter name="stroke">#000000</CssParameter>                  <CssParameter name="stroke-width">1</CssParameter>                </Stroke>               </PolygonSymbolizer>             <TextSymbolizer>                 <Label>                   <ogc:PropertyName>Cluster</ogc:PropertyName>                 </Label>                 <Halo>                   <Radius>3</Radius>                   <Fill>                     <CssParameter name="fill">#FFFFFF</CssParameter>                   </Fill>                 </Halo>               </TextSymbolizer>                </Rule>             <Rule>               <Name>min</Name>               <Title>From 0 Less than 92</Title>               <ogc:Filter>                 <ogc:And>                   <ogc:PropertyIsGreaterThanOrEqualTo>                     <ogc:PropertyName>PS_GPRS_to_WCDMA_HOSR</ogc:PropertyName>                     <ogc:Literal>0</ogc:Literal>                   </ogc:PropertyIsGreaterThanOrEqualTo>                   <ogc:PropertyIsLessThan>                     <ogc:PropertyName>PS_GPRS_to_WCDMA_HOSR</ogc:PropertyName>                     <ogc:Literal>92</ogc:Literal>                   </ogc:PropertyIsLessThan>               </ogc:And>               </ogc:Filter>               <PolygonSymbolizer>                 <Fill>                   <CssParameter name="fill">#2C6700</CssParameter>                 </Fill>               </PolygonSymbolizer>           <TextSymbolizer>                 <Label>                   <ogc:PropertyName>Cluster</ogc:PropertyName>                 </Label>                 <Halo>                   <Radius>3</Radius>                   <Fill>                     <CssParameter name="fill">#FFFFFF</CssParameter>                   </Fill>                 </Halo>               </TextSymbolizer>             </Rule>             <Rule>               <Name>PS_GPRS_to_WCDMA_HOSR</Name>               <Title>From 92 Less Than 94</Title>               <ogc:Filter>                 <ogc:And>                   <ogc:PropertyIsGreaterThanOrEqualTo>                     <ogc:PropertyName>PS_GPRS_to_WCDMA_HOSR</ogc:PropertyName>                     <ogc:Literal>92</ogc:Literal>                   </ogc:PropertyIsGreaterThanOrEqualTo>                   <ogc:PropertyIsLessThan>                     <ogc:PropertyName>PS_GPRS_to_WCDMA_HOSR</ogc:PropertyName>                     <ogc:Literal>94</ogc:Literal>                   </ogc:PropertyIsLessThan>                 </ogc:And>               </ogc:Filter>               <PolygonSymbolizer>                 <Fill>                   <CssParameter name="fill">#004040</CssParameter>                 </Fill>               </PolygonSymbolizer>           <TextSymbolizer>                 <Label>                   <ogc:PropertyName>Cluster</ogc:PropertyName>                 </Label>                 <Halo>                   <Radius>3</Radius>                   <Fill>                     <CssParameter name="fill">#FFFFFF</CssParameter>                   </Fill>                 </Halo>               </TextSymbolizer>             </Rule>         <Rule>               <Name>third_PS_GPRS_to_WCDMA_HOSR</Name>               <Title>From 94 Less Than 95</Title>               <ogc:Filter>                 <ogc:And>                   <ogc:PropertyIsGreaterThanOrEqualTo>                     <ogc:PropertyName>PS_GPRS_to_WCDMA_HOSR</ogc:PropertyName>                     <ogc:Literal>94</ogc:Literal>                   </ogc:PropertyIsGreaterThanOrEqualTo>                   <ogc:PropertyIsLessThan>                     <ogc:PropertyName>PS_GPRS_to_WCDMA_HOSR</ogc:PropertyName>                     <ogc:Literal>95</ogc:Literal>                   </ogc:PropertyIsLessThan>                 </ogc:And>               </ogc:Filter>               <PolygonSymbolizer>                 <Fill>                   <CssParameter name="fill">#D0CA9C</CssParameter>                 </Fill>               </PolygonSymbolizer>           <TextSymbolizer>                 <Label>                   <ogc:PropertyName>Cluster</ogc:PropertyName>                 </Label>                 <Halo>                   <Radius>3</Radius>                   <Fill>                     <CssParameter name="fill">#FFFFFF</CssParameter>                   </Fill>                 </Halo>               </TextSymbolizer>             </Rule>                  <Rule>               <Name>Large_PS_GPRS_to_WCDMA_HOSR</Name>               <Title>Greater Than 95</Title>               <ogc:Filter>                 <ogc:PropertyIsGreaterThan>                   <ogc:PropertyName>PS_GPRS_to_WCDMA_HOSR</ogc:PropertyName>                   <ogc:Literal>98.5</ogc:Literal>                 </ogc:PropertyIsGreaterThan>               </ogc:Filter>               <PolygonSymbolizer>                 <Fill>                   <CssParameter name="fill">#000000</CssParameter>                 </Fill>               </PolygonSymbolizer>           <TextSymbolizer>                 <Label>                   <ogc:PropertyName>Cluster</ogc:PropertyName>                 </Label>                 <Halo>                   <Radius>3</Radius>                   <Fill>                     <CssParameter name="fill">#FFFFFF</CssParameter>                   </Fill>                 </Halo>               </TextSymbolizer>             </Rule>           </FeatureTypeStyle>         </UserStyle>       </NamedLayer>     </StyledLayerDescriptor>      ![enter image description here](http://i.stack.imgur.com/Mfqw3.png)               items.push({                     xtype: "gx_mappanel",                     ref: "mapPanel",                                 region: "center",                                 map: {                               numZoomLevels: 19,                                         controls: controls                                        },                     zoom:8,                     center:[lon,lat],                                    layers: [                                         new OpenLayers.Layer.WMS( "TBF Drop Rate DL ",                          url,                           {layers: 'NCellGisData:TBF_DROP_RATE_DL_DAILY' ,transparent: "true",format: "image/png",tiled:"yes"},                          {                               buffer: 0,                              isBaseLayer :true,                              tiled: true                          }                      )                                ]                      });


title: Is there a dissolve function in PostGIS other than st_union?

text: I'm looking for a function to dissolve shared boundaries between polygon features in a table. ST_UNION() almost does what I'm looking for, but it creates a multipolygon from all polygons in the layer regardless of whether they share a common boundary or not. I'd rather only dissolve boundaries between polygons that touch each other. I figured, there should be some way using ST_TOUCHES() but then the need for a dissolve function seems so common that I would be surprised if there is no built-in function to achieve this. The use case looks like this: I downloaded Corine Landcover data for a big European country and I want to dissolve boundaries between different forest types (approx. 75,000 polygons in one table). I tried ST_UNION, but it fails me with an "out of memory" error (30,000 polygons did work though):               create table corine00 as        select st_union(the_geom) as the_geom,               sum(area_ha) as area_ha,              substr(code_00,1,2) as code_00       from clc00_c31_forests       group by substr(code_00,1,2)      _Note: All forest codes start with '31' and I'm using PostGIS 1.4, GEOS version: 3.2.0-CAPI-1.6.0_


title: Is it possible to change the field length of a shapefile to over 255?

text: The maximum field length that I can specify is 255 and because of that I'm having problems with the input attributes, which have a size greater than 255. What alternatives are there for having longer field lengths?


title: How to visualize Google Fusion Table Map using JavaScript?

text: The simplest question. When you create a google Fusion Map with geographic data, Google provides you with an iframe link to display the Map on your website. But i need to display that information through Javascript for customization etc. So how do i go about it, some basic and newbie walkthrough will be appreciated.


title: Data Driven Pages and Attribute tables

text: I was wondering how I can show ID/page specific attributes on a map book project that has already been made? I recently took over our GIS mapping duties for a former coworker who retired. He had already made a map book project using python for Food plot plantings, but there are no Attributes listed on each map page. I am working with 10.2 and I would appreciate any help. I am very new to Arc and also to this site. Thanks


title: Split a Polygon that Crosses International Date Line, ArcPy

text: I have a lots of existing data in WGS-1984 (too much to manually edit). I need to split these lines and polygons by the international date line. More projection information: GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]] Sample Coordinates: ([170, 0], [-170, 0], [-170, 10], [170, 10], [170, 0]) Does anyone have any python code to do this? For regular polygons like this square it would be easy to detect if the vertical line crossing -180 (anti-meridian), but most polygons aren't nice squares. So if I could give a set of points and detect and split the polygon into a multipart polygon would be what I'm trying to do.


title: How can I create a pdf map at a high resolution while still keeping the file size manageable?

text: I have numerous layers in shapefile format that contain a lot of data across a large area. I am trying to create a .pdf file that shows all of the area and I want it to be in good quality, so that the detail is still there when zoomed in. I tried to use the QGIS print compressor but it won't allow me to produce the best quality because the document is too big and opening it in high resolution results in an error. Is there another way to make a .pdf from my map layers?


title: QGIS Plugins - DLL load failed: %1 is not a valid Win32 application

text: This is my first question so please go easy. I am trying to develop a Plugin for QGIS. I made my plugin using the "plugin builder", then compiled the .qrc and .ui files with PySide-rcc.exe and PySide.uic.py respectively. This all seems satisfactory. However, my first problem arises when the plugin loads as the QGIS and Python (PySide) libraries are not in the same place.               ImportError: No module named PySide      I resolved this by adding a reference to the PySide path at the start of the compiled .ui module:               Import sys     Sys.path.append("C:\\Python27\\Lib\\site-packages")      Unfortunately when I run it again I get the critical error:               ImportError: DLL load failed: %1 is not a valid Win32 application.      Google searches are leading me to believe that this is caused by an incompatibility between 32bit and 64bit modules, however, I cannot easily download different versions as they are supplied under my companies IS policy. This seems to apply to all the QGIS modules as i can not access any modules even from the python console:               >>> import sys     >>> sys.path.append("C:/Program Files (x86)/Quantum GIS Lisboa/apps/qgis/python")     >>> for path in sys.path:     print path          C:\Windows\system32     C:\Python27\Scripts     D:\HRW\VET\HrwPyLibs     D:\HRW\VET\HrwPyLibs\Xdmf     D:\HRW\VET\HrwPyLibs\Converters     C:\Python27\python27.zip     C:\Python27\DLLs     C:\Python27\lib     C:\Python27\lib\plat-win     C:\Python27\lib\lib-tk     C:\Python27     C:\Python27\lib\site-packages     C:\Python27\lib\site-packages\PIL     C:\Python27\lib\site-packages\win32     C:\Python27\lib\site-packages\win32\lib     C:\Python27\lib\site-packages\Pythonwin     C:/Program Files (x86)/Quantum GIS Lisboa/apps/qgis/python     >>> from qgis.core import QgsFeatures          Traceback (most recent call last):     File "<pyshell#5>", line 1, in <module>     from qgis.core import QgsFeatures     ImportError: DLL load failed: %1 is not a valid Win32 application.      Has anyone else experienced this problem or is there an obvious issue that i have not noticed? Thanks, Chris Running: Windows 7 (64bit), Python 2.7.2 (64bit), QGIS 1.8.0 (???)


title: ArcGIS Python Script Buffer

text: I have a problem, I'm trying to create a buffer as part of a code but I keep getting the following error: ExecuteError: Failed to execute. Parameters are not valid. ERROR 000735: Distance [value or field]: Value is required Failed to execute (Buffer). I set the buffer distance in the script toolbox in ArcGIS but it doesn't seem to recognise it. Here is the code I'm using:               in_features = "Thames"     out_feature_class = "Flood_R_A"     # Run the Buffer Tool     arcpy.Buffer_analysis (in_features, out_feature_class, arcpy.GetParameterAsText(5), "FULL", "ROUND", "ALL", "")      Does anybody know what I'm doing wrong? Thanks very much.


title: custom toolbar combobox: issues with adding functionality

text: I've added a combo box to my custom toolbar in QGIS (based on this thread QGIS - Add a combobox to a toolbar), but it doesn't populate unless I reload the plugin.               def __init__(self, iface):         ...         self.toolbar = self.iface.addToolBar("SPEED")         self.activeLayer = None          def initGui(self):         ...         self.projCombo = QComboBox(self.iface.mainWindow())              self.projCombo.clear()              for layer in self.iface.legendInterface().layers():             if layer.type() == QgsMapLayer.VectorLayer:                 layerName = layer.name()                 self.projCombo.addItem(layer.name(), layer.id())              self.projComboAction = self.toolbar.addWidget(self.projCombo)         self.projCombo.setToolTip("Activate Layer")         QObject.connect(self.projCombo,SIGNAL("currentIndexChanged(int)"),self.myActiveLayer)          def myActiveLayer(self, index):         registry = QgsMapLayerRegistry.instance()         activeID = str(self.projCombo.itemData(index))         self.activeLayer = registry.mapLayer(activeID)         self.iface.setActiveLayer(self.activeLayer)


title: Where can I get high-resolution (at least 1 foot) imagery of California?

text: Is there a national site or state site that will allow me to download High Res (1') aerial imagery of California? I have tried Cal-Atlas Download but they are at one meter. I have also tried USGS Viewer and selecting by county, but when I do that it gets broken up into 100+ chunk images and only covers about 10% of the county. Any help would be greatly appreciated. The specifics of what I am looking for is California High Res aerial imagery (1') by counties. Mrsid would be ideal, but JPEG2000 is fine too. Mosaic would be ideal, but tiles are fine as well. Thank you


title: SEXTANTE Saga-grid normalisation and KBS

text: I tried to use the saga tool grid normalisation. The result is ok but the KBS has changed. Is this an error?


title: How to remove the key control so users won't be able to use - and + to zoom?

text: I am using Openlayers on Drupal 7 and I'm trying to remove the key control so the person won't be able to use the key - and + to zoom.               for (map in Drupal.settings.openlayers.maps) {         data = jQuery('#' + map).data('openlayers').openlayers;         jQuery(data.controls).each(function(){             data.removeControl((this));         });     }      So with this code I delete all the controls, but in the end it's still working ! On the file openlayers_behavior_keyboarddefaults.js if I comment the line `Drupal.openlayers.addControl(data.openlayers, 'KeyboardDefaults');` The keyboard zoom is not working ! In drupal there is an option witch can do that, but that not what I'm looking for. If I don't find any solution I still can change the value in the DataBase but I would like not using this method, (I'd prefere to learn OL instead :)) Do you have any ideas ? Thanks !


title: Problem with a large number of markers on an OpenLayers map

text:
I have created a map using openlayers. On this map I place markers. Coordinates of the markers are taken from my database (sqlserver 2008), the quantity of markers is about 1500. The map is displayed normally, but the markers aren't put down. The browser opens, the map is drawn, and then it starts breaking, since on the map there are a large number of markers. How do I fix this with the minimum change of a code (if this is the problem). Can I make use of any caching? Appendix mvc. I will try to send all code. Client Side:                   var map;         var markers;         var marker_gmap = [];          function ejecutar() {         init(3);         //loadMarkers();     }     function init(b,kor_1,kor_2) {         if (b == 3) {                       map = new OpenLayers.Map("basicMap", {                 controls: [                     new OpenLayers.Control.Navigation(),                     new OpenLayers.Control.PanZoomBar(),                     new OpenLayers.Control.LayerSwitcher(),                     new OpenLayers.Control.Attribution()],                 maxExtent: new OpenLayers.Bounds(-20037508.34, -20037508.34, 20037508.34, 20037508.34),                 maxResolution: 156543.0399,                 numZoomLevels: 2,                 units: 'm',                 projection: new OpenLayers.Projection("EPSG:900913"),                 displayProjection: new OpenLayers.Projection("EPSG:4326")             });         }             // Define the map layer             // Here we use a predefined layer that will be kept up to date with URL changes             layerMapnik = new OpenLayers.Layer.OSM.Mapnik("MapaCiudad");             map.addLayer(layerMapnik);             var lonLat = new OpenLayers.LonLat(50.5206298828125, 55.15881723298661).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());             //map.setCenter(new OpenLayers.LonLat(-3.862788677215576, 43.4669443349282) // Center of the map             map.zoomTo(9);             map.setCenter(lonLat, 19);              }         //создаем дорогу         var lineLayer = new OpenLayers.Layer.Vector("Линии");          map.addLayer(lineLayer);                             map.addControl(new OpenLayers.Control.DrawFeature(lineLayer, OpenLayers.Handler.Path));              var points = new Array(                 new OpenLayers.Geometry.Point(50.05783, 55.299518),            new OpenLayers.Geometry.Point(50.062724, 55.290132),            new OpenLayers.Geometry.Point(50.083282, 55.273152),            new OpenLayers.Geometry.Point(50.238518, 55.201065),            new OpenLayers.Geometry.Point(50.261606, 55.195401),                      new OpenLayers.Geometry.Point(50.304834, 55.184708)                        );                   var line = new OpenLayers.Geometry.LineString(points);         line.transform(new OpenLayers.Projection("EPSG:4326"), new OpenLayers.Projection("EPSG:900913"));              var style = {              strokeColor: '#0000ff',              strokeOpacity: 0.5,             strokeWidth: 5         };              var lineFeature = new OpenLayers.Feature.Vector(line, null, style);         lineLayer.addFeatures([lineFeature]);                        //создаем маркер         markers = new OpenLayers.Layer.Markers("Marcadores");         map.addLayer(markers);              if (b == 2)          {                                 ////=================  =========стили для маркеров и тут хранятся координаты                 var size = new OpenLayers.Size(30, 30);                 var offset = new OpenLayers.Pixel(-(size.w / 2), -size.h);                      var location = new OpenLayers.LonLat(kor_1, kor_2).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());                 var icon = new OpenLayers.Icon('../Content/themes/base/images/pen.png', size, offset);                 markers.addMarker(new OpenLayers.Marker(location, icon.clone()));                      markers.events.register("click", markers, function(e){                     popup = new OpenLayers.Popup.FramedCloud("chicken",                     new OpenLayers.LonLat(kor_1,kor_2),                     new OpenLayers.Size(200, 200),                     "I was here
",                     null, true);                     map.addPopup(popup);                 });              }      Server Side:               public class KartaController : Controller     {         DataClasses1DataContext db = new DataClasses1DataContext();//подсоединяем нашу бд.                             public ActionResult Index()         {             List<koordinats_piket> info = new List<koordinats_piket>();                  var result = db.Координаты_пикетов.Select(all => all);                  foreach (var a in result)             {                 for (int i = 0; i <= 10; i++)                 {                     // перевод из формата ddmmss в dddddd                     string[] parts = a.Долгота.Split(' ');                     double Dolgota = 0;                     if (parts.Count() > 0)                         Dolgota += double.Parse(parts[0].Replace('.', ','));                     if (parts.Count() > 1)                         Dolgota += double.Parse(parts[1].Replace('.', ',')) / 60d;                     if (parts.Count() > 2)                         Dolgota += double.Parse(parts[2].Replace('.', ',')) / 3600d;                     string[] parts2 = a.Широта.Split(' ');                          double Shirota = 0;                     if (parts2.Count() > 0)                         Shirota += double.Parse(parts2[0].Replace('.', ','));                     if (parts2.Count() > 1)                         Shirota += double.Parse(parts2[1].Replace('.', ',')) / 60d;                     if (parts2.Count() > 2)                         Shirota += double.Parse(parts2[2].Replace('.', ',')) / 3600d;                          info.Add(new koordinats_piket                     {                         Shirota = Shirota.ToString().Replace(',', '.'),                         Dolgota = Dolgota.ToString().Replace(',', '.')                     });                     ViewBag.Data = info;                 }                  }                  return View("Index");         }


title: How to create a topologically correct dataset in PostGIS (with GRASS)?

text: I have shapefiles which I have loaded in postgis and now i am trying to use geometric function in postgis like ST_intersect and they fail because the data is not topological correct. I have tried to use the function st_isvalid and others and could not correct the data. As a last resort i have loaded the data into grass which automatically builds topology and trying to export that layer into postgis fails with an error saying gid already exist. Also, trying to export as a shapefile works but i encounter a problem when i load the shapefile back to postgis and try to do my clip as it complains that geometric column contains z column but geometry does not. How best can i attend to these?


title: Make many lines in one layer (Python)

text: I what to create many lines with this code:               v_layer = QgsVectorLayer("LineString", "cable", "memory")     pr = v_layer.dataProvider()     seg = QgsFeature()     seg.setGeometry(QgsGeometry.fromPolyline([line_start, geomPoint]))     pr.addFeatures( [ seg ] )     v_layer.updateExtents()     QgsMapLayerRegistry.instance().addMapLayers([v_layer])      Buth this create one layer for each of this code. How can I create all in one layer.


title: WMS 1.3.0 from ArcGIS Server not work in GeoExt (OpenGeo Suite 3.0.2)

text: I used geoext sample app as in the example. added a new source and layers. but does not work: warn message "Non-existing source 'rs' referenced in layer config". but the response from the server comes (I see it in Firebug)! server ArcGIS Server and WMS version 1.3.0 http://maps.rosreestr.ru/ArcGIS/services/CadastreNew/CadastreWMS/MapServer/WMSServer?request=GetCapabilities&service=WMS I'm just starting to learn javascript                /**      * Add all your dependencies here.      *      * @require widgets/Viewer.js      * @require plugins/LayerTree.js      * @require plugins/OLSource.js      * @require plugins/OSMSource.js      * @require plugins/WMSCSource.js      * @require plugins/WMSSource.js // for my source      * @require plugins/BingSource.js      * @require plugins/GoogleSource.js        * @require plugins/ZoomToExtent.js      * @require plugins/NavigationHistory.js      * @require plugins/Zoom.js      * @require plugins/AddLayers.js      * @require plugins/RemoveLayer.js      * @require RowExpander.js      * @require plugins/WMSGetFeatureInfo.js      * @require plugins/FeatureManager.js      * @require plugins/FeatureEditor.js      * @require plugins/FeatureGrid.js      * @require plugins/DrawBox.js      * @require plugins/BoxInfo.js      */          var app = new gxp.Viewer({         portalConfig: {             layout: "border",             region: "center",                  // by configuring items here, we don't need to configure portalItems             // and save a wrapping container             items: [{                 id: "centerpanel",                 xtype: "panel",                 layout: "fit",                 region: "center",                 border: false,                 items: ["mymap"]             }, {                 id: "westpanel",                 xtype: "container",                 layout: "fit",                 region: "west",                 width: 200             },{                 id: "south",                 xtype: "container",                 layout: "fit",                 region: "south",                 border: false,                 height: 200             }, {                 id: "southpanel",                 xtype: "container",                 layout: "fit",                 region: "south",                 height: 100             }             ],             bbar: {id: "mybbar"}         },              // configuration of all tool plugins for this application         tools: [{             ptype: "gxp_layertree",             outputConfig: {                 id: "tree",                 border: true,                 tbar: [] // we will add buttons to "tree.bbar" later             },             outputTarget: "westpanel"         }, {             ptype: "gxp_addlayers",             actionTarget: "tree.tbar"         }, {             ptype: "gxp_removelayer",             actionTarget: ["tree.tbar", "tree.contextMenu"]         }, {             ptype: "gxp_zoomtoextent",             actionTarget: "map.tbar"         }, {             ptype: "gxp_zoom",             actionTarget: "map.tbar"         }, {             ptype: "gxp_navigationhistory",             actionTarget: "map.tbar"         }, {             ptype: "gxp_wmsgetfeatureinfo",             featureManager: "states_manager",             outputConfig: {                 width: 700             },             actionTarget: {                 target: "map.tbar",                 index: 1             }         }, {             ptype: "gxp_featuremanager",             id: "states_manager",             paging: false,             autoLoadFeatures: true,             layer: {                 source: "local",                 name: "geo:fence"             }         }, {             ptype: "gxp_featureeditor",             featureManager: "states_manager",             autoLoadFeature: true         }, /*{             ptype: "gxp_featuregrid",             featureManager: "states_manager",             outputConfig: {                 loadMask: true             },             outputTarget: "south"         },*/ {             ptype: "myapp_drawbox",             id: "drawbox",             actionTarget: "map.tbar"         }, {             ptype: "myapp_boxinfo",             boxTool: "drawbox",             outputTarget: "southpanel"         }         ],              // layer sources         sources: {             local: {                 ptype: "gxp_wmscsource",                 url: "/geoserver/wms",                 version: "1.1.1"             },             osm: {                 ptype: "gxp_osmsource"             },             rs: {                 ptype: "gxp_wmssource",                 url: "http://maps.rosreestr.ru/ArcGIS/services/CadastreNew/CadastreWMS/MapServer/WMSServer"                 ,transparent: true,                 format: "png",                 version: "1.3.0"             },             bing: {                 ptype: "gxp_bingsource"             },             google: {                 ptype: "gxp_googlesource"             }         },              // map and layers         map: {             id: "mymap", // id needed to reference map in portalConfig above             title: "Map",             projection: "EPSG:3857",             center: [4187314.9432233, 7447312.6747233],             zoom: 17,             layers: [{                 source: "osm",                 name: "mapnik",                 group: "background"             }, {                 source: "bing",                 name: "Aerial",                 title: "Bing Map",                 group: "background"             }, {                  source: "google",                 name: "SATELLITE",                 group: "background"             }, {                  source: "rs",                 name: "22,21,20,19,18,16,15,14,13,11,10,9,7,6,4,3,2,1",                 //,group: "background",                 visibility: true                 }, {                 source: "local",                 name: "geo:roadcover",                 selected: true,                 visibility: true             }, {                 source: "local",                 name: "geo:bridge_polygon",                 visibility: true                 }, {                 source: "local",                 name: "geo:cadastre_s",                 visibility: true             }, {                 source: "local",                 name: "geo:fence",                 visibility: false             }, {                 source: "local",                 name: "geo:curbs",                 visibility: false             }, {                 source: "local",                 name: "geo:layout_polygon",                 visibility: false             }, {                 source: "local",                 name: "geo:RoadInternodalSegment",                 visibility: true             }             ],             items: [{                 xtype: "gx_zoomslider",                 vertical: true,                 height: 100             }]         }             });      this screenshot from Firebug http://gis- lab.info/forum/download/file.php?id=6569&sid=2c5226b95b2cb52e97280be1d6039655 Sorry for my bad english


title: How to avoid random transparent pixels in georeferenced grayscale raster images?

text: I'm in the process of georeferencing some old black and white aerial pictures from 1990 in QGIS 2.4. So far, this is business as usual, no problems. Of course I get the usual black triangles, because I'm reprojecting them to EPSG:25833. So I checked "use 0 for transparency when needed". But now my georeferenced pictures are spotted with occasional transparent pixels, because of course there are legitimate black pixels all over my old aerial pictures. How do I avoid this? Is there any workaround available? Maybe change the no- data color value to some better value? And most important, how can I do this for ~50 files as economically as possible?


title: Viewing/understanding NetCDF files

text: NetCDF seems to be a scientific standard which seems to be rather common in oceanography and atmospheric sciences. I'd like to know more about it. How does the NetCDF format work, structure wise? Do you have a columned sturcture, like: X, Y, Z, ValueA Can theses files be translated into something like a CSV format? I'll paste an example from http://www.unidata.ucar.edu/software/netcdf/docs/netcdf- tutorial.html#pres_005ftemp_005f4D below. What would a single entry look like for a single point in time and space?                   netcdf pres_temp_4D {      dimensions:         level = 2 ;         latitude = 6 ;         longitude = 12 ;         time = UNLIMITED ; // (2 currently)      variables:         float latitude(latitude) ;             latitude:units = "degrees_north" ;         float longitude(longitude) ;             longitude:units = "degrees_east" ;         float pressure(time, level, latitude, longitude) ;             pressure:units = "hPa" ;         float temperature(time, level, latitude, longitude) ;             temperature:units = "celsius" ;      data:            latitude = 25, 30, 35, 40, 45, 50 ;            longitude = -125, -120, -115, -110, -105, -100, -95, -90, -85, -80, -75, -70 ;            pressure =        900, 901, 902, 903, 904, 905, 906, 907, 908, 909, 910, 911,        912, 913, 914, 915, 916, 917, 918, 919, 920, 921, 922, 923,        924, 925, 926, 927, 928, 929, 930, 931, 932, 933, 934, 935,        936, 937, 938, 939, 940, 941, 942, 943, 944, 945, 946, 947,        948, 949, 950, 951, 952, 953, 954, 955, 956, 957, 958, 959,        960, 961, 962, 963, 964, 965, 966, 967, 968, 969, 970, 971,        972, 973, 974, 975, 976, 977, 978, 979, 980, 981, 982, 983,        984, 985, 986, 987, 988, 989, 990, 991, 992, 993, 994, 995,        996, 997, 998, 999, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007,        1008, 1009, 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1018, 1019,        1020, 1021, 1022, 1023, 1024, 1025, 1026, 1027, 1028, 1029, 1030, 1031,        1032, 1033, 1034, 1035, 1036, 1037, 1038, 1039, 1040, 1041, 1042, 1043,        900, 901, 902, 903, 904, 905, 906, 907, 908, 909, 910, 911,        912, 913, 914, 915, 916, 917, 918, 919, 920, 921, 922, 923,        924, 925, 926, 927, 928, 929, 930, 931, 932, 933, 934, 935,        936, 937, 938, 939, 940, 941, 942, 943, 944, 945, 946, 947,        948, 949, 950, 951, 952, 953, 954, 955, 956, 957, 958, 959,        960, 961, 962, 963, 964, 965, 966, 967, 968, 969, 970, 971,        972, 973, 974, 975, 976, 977, 978, 979, 980, 981, 982, 983,        984, 985, 986, 987, 988, 989, 990, 991, 992, 993, 994, 995,        996, 997, 998, 999, 1000, 1001, 1002, 1003, 1004, 1005, 1006, 1007,        1008, 1009, 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1017, 1018, 1019,        1020, 1021, 1022, 1023, 1024, 1025, 1026, 1027, 1028, 1029, 1030, 1031,        1032, 1033, 1034, 1035, 1036, 1037, 1038, 1039, 1040, 1041, 1042, 1043 ;            temperature =        9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,        21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,        33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,        45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56,        57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68,        69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80,        81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92,        93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104,        105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116,        117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128,        129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,        141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152,        9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,        21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,        33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44,        45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56,        57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68,        69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80,        81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92,        93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104,        105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116,        117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128,        129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140,        141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152 ;      }


title: Algorithm to find distance of an uneven polygonal road

text: While working for my summer internship I have got a task to implement an algorithm to find the crosssecting points of two roads or more and then place that cross-section point a number and then find the distance of the previous roads to the new point and update it in the table. I tried **Ramer Douglas Peucker Line Simplification Algorithm** to convert the road into a straight line and then find the intersection point but the point coming after this is not exactly the cross section point and the distance coming is also not the exact. Please help.


title: How does the deactivate function of an ArcGIS Python Add-in Tool work?

text: I have not been able to figure out how the deactivate function of a Python Add-in Tool works in ArcGIS. The help page that mentions the function, and that it 'causes the tool to no longer be the active tool' is here: http://resources.arcgis.com/en/help/main/10.1/index.html#/Tool/014p00000027000000/. I cannot find any examples of it being used. The Tool class looks like this:               class ExampleTool(object):         """Implementation for Example_addin.tool1 (Tool)"""         def __init__(self):             self.enabled = True             self.shape = "NONE"         def onMouseDownMap(self, x, y, button, shift):             # My code here, then..             self.deactivate()         def deactivate(self):             # Do I need to add something here..?      The help file seems to imply that when the function is called, the tool will deactivate / lose focus, but maybe I need to add something to the function to make that happen..?


title: Scale on map requires correction coefficient. But why?

text: I am computing the distance of a map I am getting from ArcGIS' REST services by using a calculator as provided by this answer. In a nutshell, it uses a `GeodeticCalculator` for distance computation based on latitude and longitude. I then use the distance and my display width to compute a scale. My display is currently 362*230 (custom display hence the off measurements). When comparing the distances on screen to the distances as given by Google maps, the measurement always overestimated. However, it did so by a factor of roughly 1.2. I not use this as a correction coefficient and am accurate to about 1m in 1 km. While this solution works (for now), I would like to know where this offset could come from. Below is a bit of code to show how the computation is done. Note that `scale` is a field of the class this method resides in.               /** Relevant fields */     private GeodeticCalculator calculator = new GeodeticCalculator(CRS.decode("EPSG:3857"));     private static final double CORRECTION = 1.2;          /** More code left out for reasons of brevity. */          public double computeScale(double latMin, double latMax, double lonMin, double lonMax)     {                    calculator.setStartingPosition(new DirectPosition2D(latMin, lonMin));         calculator.setDestinationPosition(new DirectPosition2D(latMax, lonMax));                 double distance = calculator.getOrthodromicDistance();         scale = distance / (Calibration.getTableWidth() / 10) / CORRECTION;         return distance;     }


title: Help choosing an appropriate GIS solution for the following question

text: I am currently researching for an appropriate GIS solution. My requirements are pretty simple:   * Ability to create circles, symbols or diagrams with transparancy tied to their geographical location (For example showing units sold and total profit for each location)   * Size of said symbols should be proportional with values within   * They should be capable of displaying values and if possible location names   * Most of these informations including coordinates are located in Excel Files   * Possibility to automate this procedure every time or at least create semiautomated profiles I found quite a few solutions such as ArcGIS and Maptitude but I am not certain if such software is required and if there isn't a simpler alternative. I was also looking at qGIS but sadly I am quite new to GIS and such a form of data visualisation, so any guidance would be appriciated.


title: Which feature has highest value within extent

text: I have a layer in which I need to find out the maximum value of a given field within the current map extent, and then return back the value from a different field. _e.g. Find state with highest population within current extent, and return the state name._ This is a hosted service on ArcGIS Online, so I thought the right way of going about this was to make use of outStatistics to determine the maximum value of my field using the max property. However, even if I specify the outFields to include the field I need to report back on, all I get back is the result of the outStatistics. For example, see this GET request.               Out Fields: POP2007,STATE_NAME,NAME     Extent: <an extent object>     Output Statistics: [{"statisticType":"max","onStatisticField":"POP2007","outStatisticFieldName":"maxPop"}]          Result:  maxPop: 1483460      **Desired response:**               Result:  maxPop: 1483460, POP2007: 1483460, STATE_NAME: Middlesex      **What is the most efficient/elegant way of calculating the maximum value of one field within the current extent, finding that record, and returning a value from a different field?** In the above example, we can forget about extent, I just want it to return the State Name that has the maximum population value. Please also disregard the fact that counties are involved.


title: How to set NULL as default value for a date field in QGIS 2.4?

text: In QGIS 2.4, i am unable to set the default value as NULL if i have not updated any value on date fields. Its automatically taking the current system date. I am expecting to set the default values(NULL) for date fields in properties of layer, since that default values should be displayed while capturing the new feature itself. It may be edited if required. Please refer the attached screen shots. ![enter image description here](http://i.stack.imgur.com/HqgKx.jpg) ![enter image description here](http://i.stack.imgur.com/Gxpp2.jpg)


title: SAGA/GDAL fails to open grid in QGIS 2.0.1 on OSX 10.6.8

text: I want to try different grid/raster spline interpolation methods using SAGA in QGIS. I'm using the kyngchaos build 2.0.1-7 for Snow Leopard. Every SAGA algorithm I try gives the following in a popup:               Oooops! The following output layers could not be open     Grid: /var/folders/XH/XHXhaF3-Hp0EDNZQjtPjAU+++TI/-Tmp-/processing/50af3f2f86b2406db31f10014e9b80d6/USER_GRID.tif     The above files could not be opened, which probably indicates that they were not correctly produced by the executed algorithm     Checking the log information might help you see why those layers were not created as expected     This algorithm requires SAGA to be run. A test to check if SAGA is correctly installed and configured in your system has been performed, with the following result:     SAGA seems to be correctly installed and configured      The log says:               Algorithm Multilevel b-spline interpolation started     grid_spline "Multilevel B-Spline Interpolation" -SHAPES "/var/folders/XH/XHXhaF3-Hp0EDNZQjtPjAU+++TI/-Tmp-/processing/34f48cb284b54abe9179871ab766300b/leveling.shp" -FIELD "Z" -TARGET 0 -METHOD 0 -EPSILON 0.0001 -LEVEL_MAX 11 -USER_XMIN 657930.8638 -USER_XMAX 657896.114 -USER_YMIN 4530501.005 -USER_YMAX 4530453.77 -USER_SIZE 100 -USER_GRID "/var/folders/XH/XHXhaF3-Hp0EDNZQjtPjAU+++TI/-Tmp-/processing/USER_GRID.tif.sgrd"     io_gdal 1 -GRIDS "/var/folders/XH/XHXhaF3-Hp0EDNZQjtPjAU+++TI/-Tmp-/processing/USER_GRID.tif.sgrd" -FORMAT 4 -TYPE 0 -FILE "/var/folders/XH/XHXhaF3-Hp0EDNZQjtPjAU+++TI/-Tmp-/processing/46cc876ca93b4f7b8345e60455a0a2f2/USER_GRID.tif"     Error: executing module [Multilevel B-Spline Interpolation]     _____________________________________________          ##### ## ##### ##     ### ### ## ###     ### # ## ## #### # ##     ### ##### ## # #####     ##### # ## ##### # ##     _____________________________________________          _____________________________________________     library path: /Applications/QGIS.app/Contents/MacOS/lib/saga/libgrid_spline.dylib     library name: Grid - Spline Interpolation     module name : Multilevel B-Spline Interpolation     author : (c) 2006 by O.Conrad     _____________________________________________          Load shapes: /var/folders/XH/XHXhaF3-Hp0EDNZQjtPjAU+++TI/-Tmp-/processing/34f48cb284b54abe9179871ab766300b/leveling.shp...                         Parameters               Points: leveling     Attribute: Z     Target Grid: user defined     Method: without B-spline refinement     Threshold Error: 0.000100     Maximum Level: 11     Update View: no          Error: Grid file could not be opened.     Error: executing module [GDAL: Export Raster]     _____________________________________________          ##### ## ##### ##     ### ### ## ###     ### # ## ## #### # ##     ### ##### ## # #####     ##### # ## ##### # ##     _____________________________________________          _____________________________________________     library path: /Applications/QGIS.app/Contents/MacOS/lib/saga/libio_gdal.dylib     library name: Import/Export - GDAL/OGR     module name : GDAL: Export Raster     author : O.Conrad (c) 2007     _____________________________________________          Load grid: /var/folders/XH/XHXhaF3-Hp0EDNZQjtPjAU+++TI/-Tmp-/processing/USER_GRID.tif.sgrd...     failed     GDAL: Export Raster: could not initialize data objects     Converting outputs     Loading resulting layers     Algorithm Multilevel b-spline interpolation finished      I used a tab delimited text file and also tried a shapefile, both containing only points which I have to have in CRS NAD 83 / UTM zone 18N EPSG:26918. Naming a new file for the parameter "Grid" gave similar results, and the parameter "Target Grid" has only one option, "[0] user defined". I tried reinstalling QGIS. I have 2.0.8 compatibility unchecked in "Options and Configuration", but I tried with it checked and restarted. It looks here like SEXTANTE used to let you choose a path for SAGA, but it appears that with Processing in 2.0.1 choosing a folder for SAGA is no longer an option. I found `libio_gdal.dylib` and `libgrid_spline.dylib` in `/Applications/QGIS.app/Contents/MacOS/lib/saga`, but I don't know what to do with them. Is the problem with SAGA or GDAL? I have GDAL 1.10.1. What should I do to get SAGA algorithms working in QGIS for OSX 10.6.8? Thanks! BTW, here is my data. I used the Z field for interpolating.               X   Y   Z   Labels     657946.114  4530468.710 53.250  Curb     657900.751  4530477.953 56.405  Station     657900.020  4530469.788 55.935  Ref Elev     657891.472  4530451.005 55.691  Pine Tree     657904.272  4530452.899 55.025  10 m down sidewalk     657915.404  4530459.198 54.502  20 m down sidewalk     657922.472  4530463.302 54.228  30 m down sidewalk     657932.883  4530468.129 53.730  40 m down sidewalk     657940.599  4530474.466 53.230  50 m down sidewalk     657927.419  4530482.176 53.976  Statue     657917.784  4530475.559 54.494  10 m from statue     657909.383  4530469.617 55.074  20 m from statue     657897.869  4530461.605 55.840  30 m from statue     657890.491  4530457.816 55.974  40 m from statue     657919.176  4530486.939 54.180  Halfway 1     657911.217  4530480.177 54.989  Halfway 2     657901.213  4530472.673 55.963  Halfway 3     657890.839  4530465.266 56.741  Halfway 4     657886.289  4530469.603 57.389  South Corner Court     657895.552  4530477.862 57.007  10 m SCC to BT     657903.860  4530485.648 55.837  20 m SCC to BT     657910.264  4530489.290 54.853  Birch Tree     657894.773  4530485.335 57.377  North Corner Court     657898.042  4530491.892 56.567  Between NCC & Black oak     657880.864  4530498.486 57.664  2nd Light     657883.579  4530500.242 57.113  10 m off 2L     657885.741  4530503.770 56.276  Gully off 2L     657896.024  4530498.490 56.084  White Rock     657945.532  4530467.694 53.413  Close


title: Distorted Google Maps layer in pdf export from QGIS 2.0.1

text: Export of a map from QGIS 2.0.1 Composer to pdf results in distortion (changed scale) of Google map layer. Why?


title: Fixing "Assigning the return value of new by reference is deprecated" error

text: I just downloaded the vertex.php, polygon.php, and polyExample.php files from this site: http://www.phpclasses.org/package/2544-PHP-Perform-geometric- operations-on-polygons.html only to find dozens of errors reading "Deprecated: Assigning the return value of new by reference is deprecated" on various lines. Does anyone know how to eliminate these errors? The script still runs and I guess I could just set error_reporting(0); but thats not really what I would like. Thank you - Brandon


title: LonLat Points to Grid of Polygons in PostGIS

text: I'm going to preface this with it's my first time using PostGIS. I'm starting out with a 5 km x 5 km grid cell in which I know the center point lon/lat (SRID=4326). I'm trying to create a polygon for each of these grid cells in PostGIS using this command:                   create table lonlat_poly as         select ST_MakeEnvelope(lon-2.5 km, lat-2.5 km, lon+2.5 km, lat+2.5 km)         as newlonlat from lonlat;      where lonlat contains the two columns lon and lat. The potential pitfall is that the simple subtraction and addition of 2.5 km is not going to be correct due to projection issues (right?). I'm sure there's a more precise way of doing this, but I haven't thought or stumbled upon anything yet. Thanks in advance for any hints you can provide!


title: Topology or out of memory errors with large dataset intersects and spatial joins in ArcGIS

text: I receive a topology error notification when intersecting a point dataset (with ~5 million points), with a polygon dataset created by buffering those points by a half mile. The goal is to create a table containing the intersection of the two datasets such that I have a list of all points within that half mile radius of each starting point. I can generate effectively identical results using either an intersection or a spatial join. My prototype of this process works fine when I work on a small subset of each dataset. When I scale up to the full dataset, the intersect operation fails with a topology error, and the spatial join fails with an out of memory error (which is plausible given the dataset size, and memory addressing limitations of a 32bit application). Is this Much of the time I do these operations in PostGIS (successfully and easily), but on this project I'm constrained to working in ArcGIS, with the assumption that my users will have only the ArcView level of licensing. I've also done these operations in spatiallite. I'd really rather not have to pull in OGR2OGR to move the datasets to spatiallite for the processing, but can if I must. Machine specs: Intel Core2 Quad (Q9550), Windows 7 (64bit), 8GB of ram, plenty of hard drive space


title: Multishading: bring them together to one Raster-Image

text: I made a multi-hillshade with 4 different light-directions and colors and stacked one above the other, each with its own transparency. Now I want to "save" the result in one raster-image. Whats the best way to do that? And is that the "right way" or are there alternatives? ![enter image description here](http://i.stack.imgur.com/VDoe0.png) Thank you! Martin


title: How to automate relative filepath when adding a new toolbox to the arcmap catalog?

text: So I'm creating an arcpy script for a custom toolbox and I want to make it so that a user can essentially utilize the script in that toolbox without having to change the source path (which I made relative in the properties of the script), how do I go about doing so in Python or any other method? I'm guessing it might be under the tool validation code somehow, but I'm not sure.


title: How to export Spatial data from MsSQL to MySQL using OpenSource/Free tools

text: I have a few tables with geometry fields in MsSQL Server 2008. I would like to export the whole table with data to MsSQL Server. Are there any open source/free tools that does this job?


title: QGIS: Making changes to vector layers stored in PostGIS

text: I have a vector layer stored in PostGIS. I split several lines in the layer and simplified others by removing vertices. When I tried to save the changes to the layer I got postgres more postgres errors about duplicate gids. Is this a result splitting features and if so how do I get around the issue? Russell


title: What is causing this QGIS processing model to fail at r.mapcalculator

text: I can't figure this out. I can run a number of tools from the processing toolbox separately with success but when I string them together in a model it keeps failing (image of log below). It looks like it is falling over at the r.mapcalculator algorithm and some Googling tells me that the error is likely a function or call somewhere that has either failed or returned an unexpected result. However I am having trouble debugging this problem, this log doesn't tell me too much and the additional logs from the processing toolbox "History and Log" doesn't shed anymore light on the issue because I don't understand what it's saying. ![Log from model output](http://i.stack.imgur.com/F0BzA.png) ![Log from "History and Log" section of the processing plugin](http://i.stack.imgur.com/jagU5.png) ![Flow of the model](http://i.stack.imgur.com/445Xg.png)


title: Name of the node and search box cartodb

text: I'm using cartodb for a project. I read the documentation yet I can't find a solution. Indeed, I need to be able to see the name of a node (which is on the name field of the bdd) without clicking on. Is that possible ? And I have another question. In the search box, is that possible to look for one of our node ? Thanks a lot Sincerely A.H


title: Including Metadata in GML

text: IS there a nice GML tutorial that gives a step by step explanation of including metadata in GML schema(or data) ?


title: Iterating over selected features in QGIS Processing

text: I used to be able to iterate over selected features using the following script in v2.0.               import processing     features = processing.getfeatures(layer)     for feature in features:       #Do whatever you need with the feature      However, this doesn't seem to work when I upgraded my QGIS to v2.2. Is there any new way on how to iterate selected vectors? Many thanks!