[Gdal-dev] Question about gdal_rasterize

[Frank Warmerdam]

Guillaume HUBY wrote:
> Frank,
> 
> I had a look on apps\gdal_rasterize.cpp and GDALRasterizeGeometries(...) in
> alg\gdalrasterize.cpp and it seems quite tricky and taking too much time
> investment to get down lower levels and get what I want.
> 
> The alternative you proposed should be OK for my purposes, but it is not an
> exact solution : think of a thin part of polygon getting inside and outside
> a pixel through the same side (yes, that's a tricky case) ...
> 
> An exact method should compute if a polygon edge cut a pixel edge and if
> pixel is inside polygon.

Guillaume,

You are correct.  My proposed approach would still have a few error
conditions.  I can't think of an exact implementation of what you want
that would not be expensive.

Best regards,
-- 
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGF, http://osgeo.org