It might be possible using PostGIS and MapServer/MapScript. It's probably possible to get the difference between a rectangle (the extent of the image) and the circle using PostGIS. With that you could draw the resulting shape over the top of the raster and save the output via GDAL.
That assumes your input raster format can pass through MapServer without pixel values being altered. Might be worth a look if Grass doesn't work out. Steve >>> On 8/13/2007 at 2:26 PM, in message <[EMAIL PROTECTED]>, "Marc Peterson" <[EMAIL PROTECTED]> wrote: > I need to clip an input raster data set by a circle and write the extracted > cells to a new raster. Then I have to repeat 35,387 times, so any solution > needs to be scriptable. The dream solution would be to issue a command with > arguments specifying the X coordinate, Y coordinate, and radius. I assume, > however, that I'll need to do some sort of intersect operation using either > a mask matrix, a rasterized vector circle, or some XML that defines the > circle. > > Is this possible? Any script/software recommendations? I started looking > in to GRASS r.circle but haven't yet gotten very far. Basically, I want to > do what the ArcGIS "Extract by Circle" tool will do, but I want to do it > much more quickly and without ESRI. > > Thanks, > Marc Peterson > Spatial Analyst > Carolina Population Center, UNC Chapel Hill > > _______________________________________________ > Discuss mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/discuss _______________________________________________ Discuss mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/discuss
