W dniu 16.05.2010 21:18, Paul Kelly pisze:
On Sat, 15 May 2010, Markus Neteler wrote:
On Sat, May 15, 2010 at 2:53 PM, Maciej Sieczka
<msiec...@sieczka.org> wrote:
OK now, so this was actually a revert of a massive update which
broke things.
Right - personally, I find it to be a major problem that we are out
of synch with GDAL now.
I agree it's rather unfortunate. But I think we would be getting a
lot more complaints and bug reports if we had kept in-sync; the way
GDAL now handles datum transformation parameters by forcing a default
choice just isn't very desirable for the case of a user setting up a
new location. Having a potentially non-optimal choice being
automatically made for them could come back to haunt them in the
future, perhaps even years into the future.
Anyway, my point is that gcs.csv as it is now in all GRASS SVN
branches lacks towgs84 definition for Pulkovo 1942(58) datum,
which results in locations created from EPSG codes [4] lacking it
too. The towgs84 should be as in [5].
@Markus, Paul
Do I simply modify gcs.csv alone or should this be a somewhat
bigger change?
GRASS already has the correct parameters for Poland. The problem is
that it doesn't recognise the datum name "Pulkovo_1942_58"; it is
looking for "Pulkovo_1942". I would recommend the patch below for
working around this problem.
Index: lib/proj/convert.c
===================================================================
--- lib/proj/convert.c (revision 42262) +++ lib/proj/convert.c
(working copy) @@ -744,6 +744,8 @@ "Militar_Geographische_Institut",
"Potsdam_Datum_83", "Deutsches_Hauptdreiecksnetz", +
"Pulkovo_1942_58", + "Pulkovo_1942", NULL };
Does the trick for location wizard at GRASS startup (e.g. for epsg 2174
a nice selection GUI pops up) and the resulting PROJ_INFO as well as
`g.proj -p' output are OK, but `g.proj -p epsg=2174' on the command line
still fails to include the towgs84 parameter set at all, so does `g.proj
-c epsg=2174'.
In 7.x I hope to change things around so we can try to work with
GDAL's new way of doing things, rather than trying to work around
it.
Does this sound acceptable for now - in particular are there any
differences between Pulkovo 1942 and Pulkovo 1942 (58) that are worth
worrying about?
I don't know. All I know is that "Pulkovo 1942 (58)" equal
"33.4,-146.6,-76.3,-0.359,-0.053,0.844,-0.84" is the official solution
for Poland.
Maciek
--
Maciej Sieczka
http://www.sieczka.org
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