In cases of cliffs and such (i.e. sudden drops in altitude), traditional photogrammetric softwares like PCI and Erdas work with break lines, as in, you literally draw a line along edges you want computed discontinuously. That is not really practical to do in command-line GDAL, though you could import a previously created line vector and tell the algorithm to process with those in mind.
2017-10-20 16:18 GMT-02:00 Andrew C Aitchison <[email protected]>: > On Fri, 20 Oct 2017, Vincent Mora wrote: > > I'll also try the gdal_polygonize approach, but I don't think it's the >> same thingl: with raster-classif + gdal_polygonize, if you have 3 >> classes 1,2,3 polygons from 1 can touch a polygon from 3, with contour >> lines there will always be a polygon of class 2 in between. >> >> Or am I missing something. >> >> If someone believes I'm doing something useless and/or stupid (that also >> happens), please do tell. >> > > Can you polygonize contours across a vertical cliff ? > If so, 2 may be "between" 1 and 3, but at some points they may all touch. > > On some maps, contours become discontinuous around cliffs and quarries. > > -- > Andrew C Aitchison > > > _______________________________________________ > gdal-dev mailing list > [email protected] > https://lists.osgeo.org/mailman/listinfo/gdal-dev >
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