Tuesday, 8 November 2016

qgis - .prj for NAD_1983_Canada_Atlas_Lambert not recognized correctly



I'm a fairly new user of QGIS and I've run into an issue that I can't seem to solve on my own. I'm trying to work with the NRCan Atlas of Canada Waterbodies SHP file but I'm having an issues re-projecting other datasets to line up with this one.


When I reviewed the .PRJ file packaged with the NRCan data, it indicates it is Lambert Conformal Conic projection with two standard parallels at 49°N and 77°N (see .PRJ text below); however, when I add the file to QGIS (v1.8.0-Lisboa) and view the layer properties, the CRS is displayed as follows:



USER:100001 - * Generated CRS (+proj=lcc +lat_1=49 +lat_0=49 +lon_0=-95 +k_0=1 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs)



Note that the second standard parallel (which should be in there as '+lat_2=77') is missing... I'm hoping this explains why my other datasets aren't lining up when I project them, but I can't seem to get QGIS to recognize the second parallel.


Suggestions? Or is this second parallel not an issue for re-projecting data?




Unmodified NRCan .PRJ file contents


 PROJCS["NAD_1983_Canada_Atlas_Lambert",

GEOGCS["GCS_North_American_1983",
DATUM["D_North_American_1983",
SPHEROID["GRS_1980",6378137.0,298.257222101]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["False_Easting",0.0],
PARAMETER["False_Northing",0.0],
PARAMETER["Central_Meridian",-95.0],
PARAMETER["Standard_Parallel_1",49.0],

PARAMETER["Standard_Parallel_2",77.0],
PARAMETER["Latitude_Of_Origin",49.0],
UNIT["Meter",1.0]]

Answer



The problem you found is an already known bug, and has some tickets for GDAL:


http://trac.osgeo.org/gdal/ticket/4605


http://trac.osgeo.org/gdal/ticket/5191


To solve the problem, Set CRS for Layer to EPSG:3979, then Save As ... to another name.


With that, a .qpj file is added with the correct EPSG code, which will QGIS force to use that.





EDIT


Ogr2ogr seems to read the projection correctly, so running


ogr2ogr -t_srs EPSG:4326 waterwgs.shp AC_1M_Waterbodies.shp 

converts the shapefiles to a CRS that QGIS can load without misplacement.


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