[GRASS5] Re: [OSRS-PROJ] Roussilhe Oblique Stereographic

[Paul Kelly]

Hello Maciek

Maciek Sieczka wrote:
> 
> > One other thing I should have said is that the dx dy dz parameters will
> > make no difference for you since you are using GRASS 5.0.x which doesn't
> > support datum transformations.
> hmm, so why does Grass 5.0.x ask for datum at the new mapset startup?

I don't know---that was before I became involved with GRASS---I imagine
the datum support was started but never finished then.

> 
> and please look at what Sam Harrell <sammyh at 3rddim.com> on 12.03.2004 18:11
> posted to osrs-proj at remotesensing.org
> -It seems a shame to omit the datum transform functionality from libproj.
> -The lack of datum transforms forces a lot of people to stick with Proj,
> even
> -though libProj is more current.
> 
> from this sentence I conclude that PROJ provides datum transf (and the
> LIBPROJ doesn't)
> so?

Yes. The version in GRASS uses the added datum functions from Frank
Warmerdam but libproj is the 'purer' projection-only version from Gerald
Evenden. Read the archives of the PROJ mailing list to get a clearer
description of the distinction between the two if you're that interested
:)

Actually the internal PROJ contained in GRASS >= 5.0.0pre4 and <5.3 has
Frank's datum functions but they are not used. 5.0.0pre3 and earlier
contains an old copy of Gerald's pure PROJ version.

> > Since you are using 5.0.x the internal GRASS version will always be
> > used. When you upgrade to 5.3 you can specify the --with-proj configure
> > option to use the pre-installed version from remotesensing.org. The
> > GRASS version has some bugfixes over the remotesensing.org version but
> > there are also some newer features missing. There is not much difference
> > between the two.
> It is not possible to compile the 5.0.x with pre-installed fresh PROJ.4 in
> anyway?

Not unless you want to do a lot of playing around with Makefiles (which
is already done for 5.3). BUT if you are really keen and persevere you
should be able to use any GRASS version < 5.3 with pure libproj
(Gerald's version).

Paul