[Proj] Datum Conversion

Michael Dennis Michael.Dennis at divestco.com
Wed Apr 20 15:30:35 EDT 2005


I'm having a datum conversion issue with gdalwarp.   I'm trying to convert and image from NAD83 to a NAD27 utm projection.  I've got it working to include the "null"  grid file but it doesn't seem to apply it to one point.  This is the message I get...

pj_apply_gridshift(): used Null transform for whole world
pj_apply_gridshift(): failed to find a grid shift table for
                      location (56.1212789dW,35215920906082.3120000dN)
   tried: @ntv2_0.gsb, at null
ERROR 1: failed to load NAD27-83 correction file
ERROR 1: GDALWarperOperation::ComputeSourceWindow() failed because

You can see the latitude is all screwy for that point.  Does that mean I have a bad file?  Shouldn't the null grid shift work regardless of the long/lat values?  I read about a patch for large longitude values but I checked and my PROJ source and it does include that, does something similar need to be done with latitude values?

Any help or workaround would be appreciated!

Mike Dennis
Divestco Inc.

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