Re: [GRASS-user] v.proj pj_transform() failed for points but not for a vector grid
On Mon, Feb 02, 2015 at 09:29:18AM +0100, Markus Metz wrote: On Sat, Jan 31, 2015 at 5:41 PM, Patrice Dumas pertu...@free.fr wrote: v.proj --verbose input=lon_lat_demand_relocated location=whole_region_demand_map_asiamed_cities Is lon_lat_demand_relocated really the point selection? It was not. I couldn't see that visually, but in fact I had relocated some points after the v.select and the visual inspection was not enough to check that they were out of the grid. From your description, the workflow is It was almost that, as said above, with a relocation of points that moved some of them outside of the grid. I readded a last v.select and now it works correctly. Thanks a lot, and sorry for the noise. -- Pat ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] v.proj pj_transform() failed for points but not for a vector grid
On Sat, Jan 31, 2015 at 5:41 PM, Patrice Dumas pertu...@free.fr wrote: 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 Is lon_lat_demand_relocated really the point selection? 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?? From your description, the workflow is # create grid in LAEA v.mkgrid map=region_countries_whole_grid grid=40,40 # reproject grid to latlong v.proj in=region_countries_whole_grid location= mapset= # select points with grid in latlong v.select ainput=points binput=region_countries_whole_grid atype=point btype=area operator=overlap output=points_selected # reproject selected points to LAEA v.proj in=points_selected location=whole_region_demand_map_asiamed_cities mapset= # test: project grid back to LAEA v.proj in=region_countries_whole_grid location=whole_region_demand_map_asiamed_cities mapset= Am I doing something silly, or does it looks like a bug? If you are sure that v.proj fails with the selected points, it is a bug. v.proj will likely fail with all points if the points are distributed all over the world, that would be correct. 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. It's a simple sphere with radius 6370997.0, without datum. Markus M 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 grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] v.proj pj_transform() failed for points but not for a vector grid
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 grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
