Hello, grass 6.4.4 on Centos 6 (from EPEL).
Before I try to turn this into a bug I'd like to be sure that I am not doing something stupid with projections (happened in the past...). I have a Lambert equal area location and a lon-lat location, the lon-lat location covers the whole earth, the Lambert does not. I would like to project some points from the lon-lat location to the Lambert one, selecting only those points in a specific region on the Lambert map which is much smaller than the whole Lambert map. To that aim, I first do a "grid" vector over the region of interest in the Lambert location with "v.mkgrid map=region_countries_whole_grid grid=40,40" (a rather loose grid such that it is easier to project on different locations). I import that grid in the lon-lat location, use it to select points and then, back in the Lambert location use v.proj to import the points. Except that it gives me v.proj --verbose input=lon_lat_demand_relocated location=whole_region_demand_map_asiamed_cities Input Projection Parameters: +proj=longlat +a=6378137 +rf=298.257223563 +no_defs +towgs84=0.000,0.000,0.000 Input Unit Factor: 1 Output Projection Parameters: +proj=laea +lat_0=55 +lon_0=20 +x_0=0 +y_0=0 +no_defs +a=6370997 +b=6370997 Output Unit Factor: 1 Reprojecting primitives: WARNING: pj_transform() failed: latitude or longitude exceeded limits ERROR: Error in pj_do_transform Visually it seems that all the points are on the "grid" vector (which is obviously not a regular grid once projected on the lon-lat location). What is very strange is that projecting the "grid" vector back to the Lambert location works, but not projecting the points back?? Am I doing something silly, or does it looks like a bug? Additional info (similar report and lack of datum): I found a possibly similar issue reported: http://lists.osgeo.org/pipermail/grass-user/2012-June/065049.html but no definitive answer. In some answer to another thread that started with the same issue erroneously, http://lists.osgeo.org/pipermail/grass-user/2012-October/065805.html Markus asked to do a g.region -b, but in fact this does not work in the Lambert location for me, as there is no datum information. Lack of datum may be a cause of the v.proj issue above, although I doubt it. The Lambert location map comes from HYDRO1K (the eu basins): http://edcftp.cr.usgs.gov/pub/data/gtopo30hydro/ https://lta.cr.usgs.gov/HYDRO1K https://lta.cr.usgs.gov/HYDRO1KReadMe I used the grass helper to setup the region and it didn't set a datum (but it set an ellipsoid). In the .prj file that comes with vectors, there is PROJCS["Sphere_ARC_INFO_Lambert_Azimuthal_Equal_Area",GEOGCS["GCS_Sphere_ARC_INFO",DATUM["D_Sphere_ARC_INFO",SPHEROID["Sphere_ARC_INFO",6370997.0,0.0]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Azimuthal_Equal_Area"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",20.0],PARAMETER["Latitude_Of_Origin",55.0],UNIT["Meter",1.0]] but I couldn't find the "D_Sphere_ARC_INFO" datum in the datum proposed by grass. The other information from the .prj file were correctly extracted by the grass helper, as far as I can tell. -- Pat _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
