Jay, I made the plugin for QGIS, where, calculate the boundary of image with pixel value upper to zero, i believe is what you want, "footprint shape".
The plugin read all images of directories and create one vector layer with all boundary of images. For calculate, the background of image need have pixel value equal a zero. I wrote the program with Python, but, i called the GDAL functions for calculus. The name of plugin is "Image Boundary", and you can install inside QGIS(contributed repository), or read the source by http://spatialserver.net/pyqgis_1.0/contributed/imgboundary.zip Regards, Luiz Motta 2011/4/22 Jay Jennings <[email protected]>: > 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 > _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
