[Proj] Re: PROJ 4.6.0 beta1 Release

Ivan Shmakov ivan at theory.asu.ru
Tue Dec 11 15:09:48 EST 2007

	[Apparently this message didn't reached the list, so I'm
	resending it.]

>>>>> Frank Warmerdam <warmerdam at pobox.com> writes:


 >> What happens with the spherical projections? Robinson and similar?

 > The same.

 > Though the other aspect that I did was to decouple the the
 > datum/ellipsoid logic for datum shifting from the ellipsoid
 > parameters used for internal projection calculations.


 > Actually, a better demonstration of the above would be:

 > cs2cs +proj=robin +datum=GGRS87 +to +proj=latlong +datum=WGS84

 > The important distinction is that GGRS87 expands to
 > "+towgs84=-199.87,74.79,246.62 +ellps=GRS80".  The towgs84 shift is
 > applied in geocentric space, but it is very important which ellipsoid
 > is used to get to geocentric space.  In the "old" approach the sphere
 > used for robinson would have been used for the conversion to
 > geocentric.  Now, GRS80 would be used for the calculation avoiding a
 > huge unexpected sphere related shift in latitude.

	I guess, the command I've suggested half a year ago in [1]:

$ gdalwarp -of HFA \
      -s_srs '+proj=sinu +R=6371007.181 +nadgrids=@null +wktext' \
      -t_srs TARGET-SRS \
      'HDF4_EOS:EOS_GRID:"fpar8.hdf":MOD_Grid_MOD15A2:Fpar_1km' \

	could now be rewritten as:

$ gdalwarp -of HFA \
      -s_srs '+proj=sinu +R=6371007.181 +datum=WGS84' \
      -t_srs TARGET-SRS \
      'HDF4_EOS:EOS_GRID:"fpar8.hdf":MOD_Grid_MOD15A2:Fpar_1km' \

	(i. e., the source projection is spherical, but the coordinates
	used are the WGS84 ones)?  If yes, that's good!  May I suggest
	updating [2] then as well?

	Or do I miss something?

[1] http://trac.osgeo.org/gdal/ticket/1239
[2] http://proj.maptools.org/faq.html

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