[GRASS5] datum / projection

GRASS GRASS developer
1

Hi,

just note for those who don't follow PROJ.4 development (like me).
After some time, I spent by inspecting why GRASS (CVS) gives
me different (incorrect) values than PROJ.4 (4.4.7), I found that
there were done many changes in pj_transform.c (in PROJ4).
Probably also some bugs were fixed?
So we cannot get correct results in GRASS until we update proj lib.
Is it right Frank?

Radim

2

Radim Blazek wrote:

Hi,

just note for those who don't follow PROJ.4 development (like me).
After some time, I spent by inspecting why GRASS (CVS) gives me different (incorrect) values than PROJ.4 (4.4.7), I found that there were done many changes in pj_transform.c (in PROJ4).
Probably also some bugs were fixed?
So we cannot get correct results in GRASS until we update proj lib.
Is it right Frank?

Radim,

Looking through the PROJ.4 log for pj_transform() I don't see any recent
changes necessary for general use. Mostly fixes for buggy input, support
for geocentric cses, and prime meridian support and some datum shift fixes.

Are you specially referring to 7 parameter datum shift issues? If so, you
would need something current with at least pj_transform.c 1.5 (late 2002)
which would be PROJ 4.4.6 or later.

Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent

3

On Wednesday 02 April 2003 04:49 pm, Frank Warmerdam wrote:

Looking through the PROJ.4 log for pj_transform() I don't see any recent
changes necessary for general use. Mostly fixes for buggy input, support
for geocentric cses, and prime meridian support and some datum shift fixes.

Are you specially referring to 7 parameter datum shift issues?

Yes.

If so, you
would need something current with at least pj_transform.c 1.5 (late 2002)
which would be PROJ 4.4.6 or later.

Currently in GRASS: 4.4.5

Thanks. Radim

4

On Wed, 2 Apr 2003, Radim Blazek wrote:

On Wednesday 02 April 2003 04:49 pm, Frank Warmerdam wrote:
> If so, you
> would need something current with at least pj_transform.c 1.5 (late 2002)
> which would be PROJ 4.4.6 or later.

Currently in GRASS: 4.4.5

I have updated the pj_transform.c in GRASS CVS to fix this bug.

Also, currently testing using a shared external libproj with GRASS and seems
to work well so maybe we can switch over to this soon.

Paul