[postgis-users] Using grids transformation method with PostGis

[Mike Toews]

The problem is probably with the grid files and proj.4. Is there any way to
download the GSB files for testing?

You can test with cs2cs to see if the proj4 string works or not. For
example, with Canada's NTv2 grid file, I can test to see if I installed it
correctly:

cs2cs -v +proj=latlong +ellps=clrk66 +nadgrids=@ntv2_0.gsb +to +proj=latlong
+ellps=GRS80 +datum=NAD83

then type: -111 50, and I should see output with different (and correct)
coordinaets. If you see the same coordinates, then either the coordinates
are outside the grid, or the grid file is not found. (I'd love to see some
exceptions thrown somewhere in the code). If the test works for cs2cs, then
it will work for PostGIS by updating the spatial_ref_sys table with the
projection info.

-Mike

2010/6/15 Luís de Sousa <luis.a.de.sousa at gmail.com>

> Hello everyone,
>
> I have tried to sort this issue in several ways, checking the correct
> projection settings, trying other installations of PostGis but the
> problem remains: PostGis seems unable to use the proj files for the
> grid transformation method.
>
> Is this a bug that should be reported? How can I do so?
>
> Thank you,
>
> Luís
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>
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