Hello, I have a GeoTiff DEM, which is written in WGS84 and describes nodata as null. (No data means sea area.)
I want to make shaded-color-relief tiff in spherical mercator from it, so I run: gdalwarp -s_srs EPSG:4326 -t_srs EPSG:3785 -r bilinear wgs_dem.tif merc_dem.tif gdaldem color-relief -alpha -co ALPHA=YES merc_dem.tif ramp.txt merc_rel.tif gdaldem hillshade -compute_edges merc_dem.tif melc_shd.tiff hsv_merge.py merc_rel.tif melc_shd.tiff melc_shdrel.tiff But, result file melc_shdrel.tiff not contains null data. null data are all changed into value 0, so they are not transparent, and colored as ground. I tried several change to command, consequently, gdalwarp -s_srs EPSG:4326 -t_srs EPSG:3785 -srcnodata "" -r bilinear wgs_dem.tif merc_dem.tif This command makes null data not to value 0 but to -9999. "gdaldem color-relief" detect this change and make sea area as transparent. But, "gdaldem hillshade" not detect this, so sea shore shown as huge cliff, and sea area became gray. I tried '--dstnodata' or '-dstalpha' option, but they makes any good change. Is there any ways to get destination data which describes null as nodata in gdalwarp? Or, making "gdaldem hillshade" to detect -9999 as nodata? Regards, OHTSUKA Ko-hei _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
