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I am trying to create a new project using a custom proj4 string. The
parameters I specify are '+proj=utm +zone=6 +ellps=clark66
+towgs84=-5,135,172'. After creating the project however, and verifying
the projection settings using <b>g.proj -j -f -p</b> I get the
following info: <br>
<br>
-PROJ_INFO-------------------------------------------------<br>
name : Universal Transverse Mercator<br>
proj : utm<br>
ellps : wgs84<br>
zone : 6<br>
towgs84 : -5,135,172,0,0,0,0<br>
no_defs : defined<br>
-PROJ_UNITS------------------------------------------------<br>
unit : Meter<br>
units : Meters<br>
meters : 1<br>
+proj=utm +no_defs +zone=6 +a=6378137 +rf=298.257223563
+towgs84=-5,135,172,0,0,0,0 +to_meter=1<br>
<br>
Why is it not maintaining the Clarke 1866 Elliposid?<br>
<br>
<br>
<br>
Alternatively, if I specify a proj 4 string as follows: '+proj=utm
+zone=6 +datum=nad27 +towgs84=-5,135,172' and verify the created
projection using g.proj, I get the following output:<br>
<br>
-PROJ_INFO-------------------------------------------------<br>
name : Universal Transverse Mercator<br>
proj : utm<br>
datum : nad27<br>
ellps : clark66<br>
zone : 6<br>
no_defs : defined<br>
-PROJ_UNITS------------------------------------------------<br>
unit : meter<br>
units : meters<br>
meters : 1<br>
+proj=utm +no_defs +zone=6 +a=6378206.4 +rf=294.9786982
+towgs84=-22.000,157.000,176.000 +to_meter=1<br>
<br>
Here it is maintaining the correct ellipsoid, but it does not maintain
the towgs84 datum transformation parameters.<br>
<br>
<br>
<br>
Is this a bug or is my interpretation of creating custom projections
completely wrong?<br>
<br>
Thanks,<br>
<br>
Casey<br>
<br>
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