[GRASS-dev] finding the hole of a donut

[Michael Barton]

I have a vector shape with some complexly shaped empty areas inside.  
I'd like to somehow extract these empty areas--eventually as a  
raster. I want to use these interior empty space to make that part of  
a raster null.

It's kind of like wanting to extract the hole of a donut but NOT get  
the area outside the donut too.

Any suggestions as to how to go about this?

Michael