[Proj] Need help converting Goode to latlon
dturover at student.santarosa.edu
Wed Jul 22 01:39:52 EST 2009
I have shapefiles made in ArcGIS that use the Interrupted Goode Homolosine
projection. I am trying to use libproj to reproject them to lat/lon, but the
resulting shapes do not align correctly to the corresponding features in
Google Earth. Everything is pulled to the west by a small amount near the
equator and a larger amount further away from the equator.
The projection in ESRI format is Goode%20Homolosine%206378137%20sphere.prj
in that directory. The proj arguments that I am using to define Goode are:
+proj=goode +lon_0=0 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +units=m +no_defs
What sort of things might be going wrong here? How might I be able to
adjust whatever algorithm is being run to attempt to fix it? I am too new
to projections to know what is possible in these areas.
I see that the .prj file has a "<custom>" datum, but I do not know what
this implies or how to make sure proj is using it. The custom datum is:
Also, proj -lP lists PCyl and Sph as different projection classes under
+proj=goode but I cannot find anything in the proj4 documentation on
how to specify a projection class. The .prj file says that I should be
using a spherical projection. If proj defaults to a pseudocylindrical
algorithm for Goode, would it produce different results? If so, how
could I force it to run a spherical algorithm?
Thanks in advance for any help.
- David T.
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