Even, Very thanks! I could do it.
color-relief's alpha channel masks hillshade's gray sea area, so TMS tiles are become transparent. Ko-hei 2012/9/18 Even Rouault <[email protected]>: > Le lundi 17 septembre 2012 07:12:24, OHTSUKA Ko-hei a écrit : >> 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? > > Try adding -dstnodata 0 to your gdalwarp commandline. > The option -srcnodata "" is likely interpreted as equivalent to -srcnodata 0, > which should not be necessary at all, as gdalwarp will autodetect it > >> >> Or, making "gdaldem hillshade" to detect -9999 as nodata? > > In your ramp.txt, make sure that you have a line like : > "nv 0 0 0 0" > > Note: the important 0 is the 4th one, which means that the alpha component for > the nodata value (nv) will be 0. > > A quick review of hsv_merge.py shows that it should preserve the alpha band of > the colored raster. > > But to debug this more easily, make sure to check that the result of each > intermediate step is OK. > >> >> >> Regards, >> >> OHTSUKA Ko-hei >> _______________________________________________ >> 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
