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<font face="Times New Roman, Times, serif">Perhaps I'm doing
something stupid, perhaps it cannot be done at all with grid shift
files. I would very much appreciate if you would have a look at
it.<br>
<br>
I want to rubbersheet old maps with source and destination control
points in the same projection (epsg:28992). A test example is at <br>
</font><br>
<font face="Times New Roman, Times, serif">
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charset=ISO-8859-1">
<a href="http://mapserver.sara.nl/ntv2.png">http://mapserver.sara.nl/ntv2.png</a><br>
<br>
The green points are the original points, the blue points are the
locations I want them shifted to. The shift values are in
arcseconds, located at the WGS84 coordinates of the four original
points <br>
<br>
</font>id | lon | lat | dx |
dy <br>
--+---------+-----------+-------------+--------------<br>
ll | 5.3876 | 52.1561 | -52.6024 | -32.3636<br>
lr | 5.4022 | 52.1561 | 52.5918 | -32.3701<br>
ur | 5.4022 | 52.1651 | 52.6448 | 32.3504<br>
ul | 5.3876 | 52.1651 | -52.63421 | 32.3561<br>
<br>
<font face="Times New Roman, Times, serif">I created a regular grid
with gdal_grid, covering both source and destination points, and
with these four points as seeds. Then I converted that grid to
ntv2 format, both with gdal and Jose's program. The grid and ntv2
files have correct values at the correct locations.<br>
<br>
I would expect that a command like the following: <br>
<br>
cs2cs +proj=sterea +lat_0=52.15616055555555
+lon_0=5.38763888888889 +k=0.9999079 +x_0=155000 +y_0=463000
+ellps=bessel +units=m +no_defs +nadgrids=@null \<br>
+to +proj=sterea +lat_0=52.15616055555555
+lon_0=5.38763888888889 +k=0.9999079 +x_0=155000 +y_0=463000
+ellps=bessel +units=m +no_defs +nadgrids=test_shift.ntv2<br>
<br>
would convert source coordinates to destination, but no way. The
best I get are the red points.<br>
<br>
Is the idea correct? If so, how do I get it to work?<br>
<br>
Thanks in advance,<br>
<br>
Jan<br>
</font><br>
<br>
<br>
<div class="moz-cite-prefix">On 01/18/2013 06:01 PM, Jan Hartmann
wrote:<br>
</div>
<blockquote cite="mid:50F97FF9.4040804@uva.nl" type="cite">
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<font face="Times New Roman, Times, serif">Hi Jose, Gabor, Andre,<br>
<br>
I got Jose's program running without trouble, and the results
are the same as what I got with gdal. So the problem is not with
gdal, but there is something wrong with my data. I'll make a
detailed use case tomorrow and hope you can have a look at it.<br>
<br>
Jan <br>
<br>
</font>
<div class="moz-cite-prefix">On 01/18/2013 11:51 AM, Jose
Gonçalves wrote:<br>
</div>
<blockquote
cite="mid:CALHLaOTnorvUvAoHm5pxyMskjRGXRNJugW-=rZSJBs62P2VXWg@mail.gmail.com"
type="cite"> Hello<br>
<br>
I have a program to create GSB files from two long/lat
difference grids in Surfer format.<br>
<a moz-do-not-send="true"
href="http://www.fc.up.pt/pessoas/jagoncal/coordenadas/write_gsb.exe">http://www.fc.up.pt/pessoas/jagoncal/coordenadas/write_gsb.exe</a><br>
<br>
You can check with it. The longitude difference in the input
grid are in the standard way (east positive).<br>
<br>
<br>
Regards<br>
<br>
José A. Gonçalves<br>
<br>
<br>
</blockquote>
</blockquote>
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