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<font face="Times New Roman, Times, serif">Hi all,<br>
<br>
I've been experimenting with grid-shift files in ntv2 format to
rubbersheet old maps. I created a working ntv2-file as described
in<br>
<br>
<a class="moz-txt-link-freetext" href="http://lists.maptools.org/pipermail/proj/2013-January/006539.html">http://lists.maptools.org/pipermail/proj/2013-January/006539.html</a><br>
<br>
and added an epsg definition for PROJ and PostGIS. The thing works
with cs2cs and with vector transforms in PostGIS, but when I try
to warp a raster file I get lots of errors like:<br>
<br>
Inverse grid shift iterator failed to converge.<br>
pj_apply_gridshift(): failed to find a grid shift table for<br>
location (6.7638472dW,53.0926086dN)<br>
tried: MIN03001A01.ntv2<br>
<br>
and an output file with rubbish<br>
<br>
The location is within the grid. <br>
<br>
The source raster has epsg:28992, without the +towgs84 parameters
but with the ntv2 file, the output raster has epsg:28992 with the
towgs84 numbers. Essentially, the ntv2 file contains the distances
between the scanned map locations translated to an approximate
position in epsg:28992, and the correct ones. I computed the grid
with boundaries far outside the mapped regions, but this does not
seem to make a difference.<br>
<br>
Can anyone help?<br>
<br>
Jan<br>
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