Maxime, you can try the following tricks to remap your nodata value from -32768 (this is type typical value for most DEM) to 0 :
1) gdalwarp -srcnodata -32768 -dstnodata 0 src_dem.tif out_dem.tif 2) or gdalbuildvrt -srcnodata -32768 -vrtnodata 0 out_dem.vrt src_dem.tif (you need GDAL 1.7.1 for the latest) and then use gdal_contour on out_dem.tif or out_dem.vrt Le Tuesday 23 February 2010 21:54:26 Maxime Guillaud, vous avez écrit : > Hi all, > > I am trying to have gdal_contour operate on SRTM data from CGIAR > (http://srtm.csi.cgiar.org/). The problem is that this dataset has > oceans set to "nodata". This creates ugly artifacts along the shores > (you can see an example here on the red lines: > http://www.mguillaud.net/tmp/Screenshot.png - in contrast, the blue > contour lines were generated by gdal_contour from another DEM file with > sea-level at zero - however I can not use this second data source > because it has other defects). > > Now, I would like to either > 1. set all "nodata" points to an arbitrary elevation (zero) directly > in the GeoTIFF file, or > 2. make gdal_contour assume that nodata means elevation zero. > > I would be grateful if anyone can point me to a way to do either of the > above ! > > cheers, > Maxime > _______________________________________________ > 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
