Le mercredi 09 décembre 2015 19:23:16, Djordje Spasic a écrit : > Hi, > > I am downloading an open source .asc elevation files from > opentopography.org. I attached one of them in this email. Once downloaded > .asc elevation file need to be projected from WGS84 datum (EPSG 4326) to > Universal Transverse Mercator. Here is an example of how this looks like > in python GDAL for Barcelona Spain downloaded elevation model: gdalwarp > -s_srs EPSG:4326 -t_srs EPSG:32631 -r cubic BarcelonaWGS84.asc > projectedToUTM.tif So in this case the EPSG:32631 has been used as a > projection (it hasn't been picked by me), it was googled. > > But how do I know which projection to pick, depending on the location for > which the elevation data is downloaded? I googled a bit, and there are few > articles online, which suggest picking the right EPSG projection based on > UTM zone to which the downloaded elevation model belong > to:https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_ > system#/media/File:Utm-zones.jpg > > But I am not sure I understand how to choose the EPSG projection based on > UTM zone. > > How can this be done?
Formula given in http://stackoverflow.com/questions/9186496/determining-utm-zone-to-convert-from-longitude-latitude long2UTM <- function(long) { (floor((long + 180)/6) %% 60) + 1 } Take the longitude of the central point of the source raster as input Just thinking it could be interesting to have gdalwarp accept -t_srs AUTO:42001 to do that automatically: http://cite.opengeospatial.org/OGCTestData/wms/1.1.1/spec/wms1.1.1.html#auto_projections.42001 > > Thank you for the reply. > > Kind regards, > Djordje Spasic -- Spatialys - Geospatial professional services http://www.spatialys.com _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev