# Center of a polygon inside the polygon

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.

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What do you mean by shrinking the polygon? –  Fabian Apr 6 '11 at 19:09
I haven't heard of a name for it, but a more conventional characterization of it (if I understand your figure correctly) would be as the point(s) inside the polygon with maximal distance from its border. –  joriki Apr 6 '11 at 19:10
@Fabian look at @joriki's comment, that is what I meant. –  Attila O. Apr 6 '11 at 19:11
This is known as the "Medial Axis Transform (MAT)" in computer science. You can try searching for this to get more information on the algorithm. –  Matt Groff Apr 6 '11 at 19:59