[Qgis-developer] [gdal-dev] Open source API to convert raster to polygons?

[Barry Rowlingson]

Ricardo Scachetti Pereira wrote:

>     What I really need is some API or software library (preferably in C 
> or C++) that I could use to convert ESRI Arc/Info Grids (the binary 
> kind) to a Shapefile of polygons. If a library isn't available, a 
> command line utility that I can call from C/C++ would suffice.

  There's some raster-to-vector conversion tools, but I don't know any 
that produce shapefiles. However, if the output is in a sensible enough 
format then it should be easy to convert from that to shapefile.

Try these:

  http://autotrace.sourceforge.net/

  http://delineate.sourceforge.net/screenshots.html

  and see if they can successfully trace your rasters.

  Mostly these tools will smooth out the jagged edges of raster areas - 
is this what you want, or do you want your shapefiles to strictly follow 
the raster cell boundaries? That's a different problem altogether, and 
probably more easy to do...

Barry