Adam Ratcliffe schrieb: > Hi, > > I've been generating hillshade images using the SRTM3 data, these are looking > good but I've noticed some artifacts around the area of the Southern Alps of > New Zealand. These can be seen in this sample image: > http://test.geosmart.co.nz/images/relief-artifacts.png > > Being a little bit new to this I'm neither sure of why the artifacts exist > and how to remove them in the processing of the data. So far I've > experimented with some of the options to gdalwarp, on the Hiking/Biking maps > wiki page it was suggested to pass "-wt Float32 -ot Float32" to the gdalwarp > call - I observed no difference with these options. I also tried setting the > error threshold '-et' option to 0 which had no effect. > > Any suggestions on how to tackle this problem are much appreciated. >
I'm doing also my first steps with generating hillshades. The wiki page (HikingBikingMaps) helped a lot and I got my shades with the known artifacts. As I understand, these came from the SRTM3 data itself and can only be fixed with more precise data. Now comes the SRTM30 [1] dataset in play. The viewfinderpanorama website [2] lists also some alternative sources for filling the gaps, but I just cant find a way how to process all the data. Does anyone have tried to combine/merge the datasets to fix the artifacts? I would like to know the way how to do it. There is also the SRTM4 dataset from CGIAR-CSI (with fixed gaps) but this is not an option right now. Lars [1] http://dds.cr.usgs.gov/srtm/version2_1/SRTM30/ [2] http://www.viewfinderpanoramas.org/dem3.html _______________________________________________ Mapnik-users mailing list [email protected] https://lists.berlios.de/mailman/listinfo/mapnik-users
