[postgis-devel] Incorrect proj parameters in spatial_ref_sys?

[Paul Ramsey]

I think you're confused... ESRI and EPSG agree that 2964 is 
NAD_1927_Alaska_Albers_Feet, not metres. EPSG description: "Cartesian 2D 
CS.  Axes: easting, northing (X,Y). Orientations: east, north.  UoM: ftUS."

Gary Sherman wrote:

> It appears there may be an incorrect parameter in the spatial_ref_sys table 
> for some projections.
> 
> For example, SRID 2964 contains the proj4 parameter: 
> +to_meter=0.3048006096012192 
> 
> When creating a layer in SRID 2964 from WGS84 (SRID 4326) using the transform 
> function, the coordinates are incorrect. It appears that each coordinate is 
> being divided by the to_meter value during transformation. This results in a  
> y-shift on the order of 2.8 million meters and approximately a 500K meter 
> x-shift. The units of the Alaska Albers projection (2964) are meters.
> 
> Dropping the to_meter parameter from the spatial_ref_sys entry results in a 
> correct transform. 
> 
> This same behavior was noticed using ogr2ogr to transform from a geographic 
> shapefile to Alaska Albers.
> 
> SQL used to create the transformed table:
>   create table waypoints_alb as select gid, name, transform(the_geom,2964)
>   from waypoints_geo;
> 
> Comments -- or am I confused...
> 
> -gary
> 
> 
> 
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