It is true that geocentric XYZ coordinates are not very useful, without being
able to convert them to coordinate with orthometric ("geoid") ("sea level")
height.
Frank implemented 'preliminary' support for this, which i am preparing to test
now. Before expecting it to work in GDAL/OGR, i thought i should try it down
in PROJ.4 first, following the description on
http://trac.osgeo.org/proj/wiki/VerticalDatums
If i try a point near me in California, it works regularly:
cs2cs +proj=latlong +datum=WGS84 +to +proj=utm +zone=10 +datum=WGS84
-122.272778 37.871667 10
563959.68 4191825.55 10.00
But if i try to provide a geoid file (from
http://download.osgeo.org/proj/vdatum/usa_geoid2009.zip) then it seems to not
work:
cs2cs +proj=latlong +datum=WGS84 +to +proj=utm +zone=10 +datum=WGS84
+geoidgrids=g2009conus.gtx
-122.272778 37.871667 10
Rel. 4.7.1, 23 September 2009
<cs2cs>: while processing file: <stdin>, line 1
pj_transform(): Unknown error
* * 10.00
The goal is to transform the input elevation (10 meters, ellipsoidal height, i
presume) to an orthometric height (which will use the geoid, i presume).
Maybe i'm doing it wrong?
Thanks,
Ben
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