# DONUT (Dataset Of MaNifold strUcTures)


This repository contains a dataset of 3D samples made of watertight meshes and corresponding point clouds. Each sample is composed of one or several watertight mesh components and one 8192-point cloud representation.

The dataset contains **29,517 samples** in total.

## Overview

The figure below shows a few samples from the dataset together with their labels.

![A few DONUT samples and their labels](static/donut_samples.png)

## Contents

The repository is organized as follows:

```text
.
├── metadata.csv
├── obj/
│   ├── shard_0/
│   ├── shard_1/
│   └── shard_2/
└── pcd/
    ├── shard_0/
    ├── shard_1/
    └── shard_2/
```

- `obj/` contains the mesh files as `.npz` archives.
- `pcd/` contains the point clouds as `.npy` files.
- `metadata.csv` contains one row per sample with topological metadata.

There are **29,517** mesh files in `obj/` and **29,517** point cloud files in `pcd/`.

## File Format

### Meshes

Each mesh sample is stored as an `.npz` file in `obj/`. The archive contains:

- `vertices.npy`
- `faces.npy`

A sample may contain one or several watertight connected mesh components.

### Point Clouds

Each point cloud sample is stored as a `.npy` file in `pcd/`.

Each point cloud contains **8192 points** and corresponds to the sample with the same `id`.

## Sample Identification

Each sample is identified by a unique `id` string.

The same `id` is used in:

- the filename in `obj/`
- the filename in `pcd/`
- the `id` column in `metadata.csv`

For example, if a sample has id `abc123`, its files are:

- `obj/.../abc123.npz`
- `pcd/.../abc123.npy`

## Metadata

`metadata.csv` contains the following columns:

- `id`: unique identifier of the sample
- `genus`: total number of holes across all mesh components in the sample
- `components`: total number of connected mesh components in the sample
- `sample_code`: array of 6 integers describing how many components of each genus are present

## Meaning of `sample_code`

`sample_code` is an array of 6 integers:

```text
[n0, n1, n2, n3, n4, n5]
```

Here, `ni` is the number of mesh components in the sample whose genus is `i`.

So:

- `n0` is the number of genus-0 components
- `n1` is the number of genus-1 components
- `n2` is the number of genus-2 components
- `n3` is the number of genus-3 components
- `n4` is the number of genus-4 components
- `n5` is the number of genus-5 components

From `sample_code`, the metadata values are computed as:

```text
genus = sum(i * ni for i in [0, 1, 2, 3, 4, 5])
components = sum(ni for i in [0, 1, 2, 3, 4, 5])
```

In other words:

- `genus` is the total number of holes in the full sample
- `components` is the total number of connected components in the full sample

The distribution of labels in the dataset is shown below.

![Distribution of DONUT labels](static/donut_distrib.png)

## Examples

```text
sample_code = [2, 1, 0, 0, 0, 0]
```

This means:

- 2 components of genus 0
- 1 component of genus 1
- total genus = 0 * 2 + 1 * 1 = 1
- total components = 2 + 1 = 3

## Summary

DONUT is a dataset of **29,517** samples of manifold 3D structures.

Each sample provides:

- one mesh file in `.npz` format
- one 8192-point cloud in `.npy` format
- one metadata entry in `metadata.csv`

The metadata describes the global topology of each sample through its total genus, number of connected components, and component-wise genus distribution.