TITLE: Center of a polygon inside the polygon
QUESTION [6 upvotes]: What is the name of the point(s) in a polygon, calculated by "shrinking" the polygon until there's no surface left?
Example (the light areas):

Also, of possible, it would be cool to have an algorithm to calculate this in a reasonable time, given the coordinates of the edges.

REPLY [3 votes]: It's the medial axis. See also the straight skeleton.