[Proj] How to use +towgs84
Aaron Friesen
aaron at cartopac.com
Thu Feb 26 19:24:18 EST 2009
Everyone,
I'm trying to familiarize myself with proj.
I'm trying to use cs2cs to do a datum shift where a 7-parm
transformation is used. I want it to do the shift in
both directions.
"proj -ld" seems to provide a possible example. The listing
for ire65 has example towgs84 settings.
Datum: ire65
Ellipse: modif_airy (sic)
Comment: towgs84=482.530,-130.596,564.557,-1.042,-0.214,-0.631,8.15
What do I need to specify for cs2cs for both directions
of the transform?
+proj=latlong +ellps=mod_airy
+to
+proj=latlong +ellps=WGS84
seems like a resonable start. Where does the +towgs84 argument go?
How do things change in the reverse direction?
Thanks for your assistance,
Aaron
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