2

I have some vector files that come without projection. So I have to define my own projection in QGIS. The information that comes with the data reads as following:

Projection: Lambert Azimuthal
Units: Meters
Datum: None
Parameters:
6370997.24063 (radius of the sphere of reference)
100 0 0.000 (longitude of center of projection)
45 0 0.000 (latitude of center of projection)
0.00000 (false easting (meters))
0.00000 (false northing (meters))

The Lambert Azimuthal is an equal area projection. I tried to translate this into a projection definition as:

+proj=laea +lat_0=45. +lon_0=100. +x_0=0 +y_0=0 +datum=none +units=m +a=6370997.24063 +b=6370997.24063

But my data is still wrongly projected.

  • Eh? The op says "vector" – mdsumner Sep 16 '14 at 11:21
  • You'll need to give more information. What steps do you take, what do you get, and how do you determine wrongness? – mdsumner Sep 16 '14 at 11:23
3

I guess your data uses US National Atlas Equal Area, EPSG:2163:

+proj=laea +lat_0=45 +lon_0=-100 +x_0=0 +y_0=0 +a=6370997 +b=6370997 +units=m +no_defs

Note that lon_0 is negative for western longitudes. and datum=none is no official definition.

  • No it is not. It is (+)100 for the longitud. – mace Sep 16 '14 at 12:30
1

Ok, in the end I was able to assign a new projection in ArcGIS. Using the data as specified above. I still dont understand what the problem was in QGIS. Possibly the libproj library was broken.

  • I don't think the library is broken. You do need to define a datum, I think, as it's impossible to have a projection without a datum. You could just drop in WGS84. – Alex Leith Sep 24 '16 at 22:26

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