Correct, we just need the footprint of the "good" (non-NODATA) area, which will often approximate a simple 4-point polygon with no holes.
-----Original Message----- From: Elijah Robison [mailto:[email protected]] Sent: Friday, April 22, 2011 2:07 PM To: Jay Jennings Cc: [email protected] Subject: Re: [gdal-dev] Polygonize from C# ? Jay, do you basically want a footprint shape of the useful data in the Sat images (say, without the collar), or is the problem more complex, where perhaps you have a mosaic of several images and, like swiss cheese, there are no-data holes within the image? It sounds to me like you just want a footprint of the collarless area; is this correct? /Elijah Jay Jennings wrote: > I see, thanks. But since I have satellite images, this part of the doc is > alarming: "...For non-thematic raster data (such as satellite images) > the result will essentially be one small polygon per pixel, and memory and > output layer sizes will be substantial. The algorithm is primarily > intended for relatively simple thematic imagery, masks, and classification > results". > > I just want one polygon enclosing the non-zero pixels (or alternatively, > enclosing the zero pixels, then I could do a geometric > difference). Is there any way to trick the method into doing that, to maybe > avoid the heavy resource needs ? > > > -----Original Message----- > From: Even Rouault [mailto:[email protected]] > Sent: Friday, April 22, 2011 11:45 AM > To: Jay Jennings > Cc: [email protected] > Subject: Re: [gdal-dev] Polygonize from C# ? > > Selon Jay Jennings <[email protected]>: > > Generally, refering to the C/C++ doc is a good way of finding the info : > > See http://gdal.org/gdal__alg_8h.html#3f522a9035d3512b5d414fb4752671b1 > > >> Hi list, >> Can anyone point to any guidance or (preferably) examples on using >> GDAL.Polygonize() with C# bindings ? I see what the interface is, but there >> are some unexplained parameters, e.g. "string[] options". >> >> My eventual goal is to open a raster and produce a WKT POLYGON string >> enclosing the "good" (non-NoData) area of the raster. Thanks. >> >> ......................................................... >> Jay Jennings >> Senior Software Developer >> (NASDAQ: GEOY) >> [email protected] >> >> >> >> >> >> > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
