[GRASS5] Update for Spearfish sample data

[Paul Kelly]

On Fri, 9 May 2003, Markus Neteler wrote:

>
> The updated package is here:
>
> http://mpa.itc.it/markus/tmp/spearfish_grass50data.tar.gz
>
> please
>  - try with any 5.0.x
>  - try on various platforms
>
> You may simply run
>  g.region -l
> which uses PROJ4 to report the current region in Lat/Long coordinates.
>
> If reports are ok, I'll move the file to
>  http://grass.itc.it/data.html

I think it should be safe to add
datum: nad27
to the parameters. This makes it clear what is going on and will be
ignored in GRASS versions before 5.0.0pre4 when there wasn't any datum
support at all. And people using 5.0.0pre4 to 5.0.2 will be able to take
advantage of the nad2nad datum conversions that were operational in those
versions.

So the new spearfish PROJ_INFO is:

name: UTM
datum: nad27
nadgrids: conus
proj: utm
ellps: clark66
a: 6378206.4000000004
es: 0.0067686580
f: 294.9786982000
zone: 13

I have also updated g.setproj so the PROJ_INFO files it writes are this
style, with either 'nadgrids: xxx' or 'towgs84: xxx' below the datum: line.
The old format 'datumparams: towgs84=xxx' is still accepted by pj_get_kv()
etc. and will be useful if additional datum shift parameters are added to
PROJ.4 in the future (which was my original intention) but I feel
compatibility of the PROJ_INFO files with older GRASS versions is more
important.

GRASS versions 5.0.0pre4 to 5.0.2 should now only have a problem if a datum
name that wasn't present in those versions is used. (It can't be fixed by
updating the src/libes/gis/datum.table file (i.e. $(GISBASE)/etc/datum.table)
as in 5.0.0pre4 to 5.0.2 the datums were hard coded into
src/libes/proj/pj_datums.c; this has now been changed). Versions older than
5.0.0pre4 totally ignored the datum so it will cause no problems there.

This is a probably good time to remind again that for 5.0.0pre4 to 5.0.2,
when 'datum: nad27' was present in the PROJ_INFO file a datum shift parameter
of 'nadgrids: conus' was automatically assumed and any other datum
parameters in the PROJ_INFO file were ignored. For the latest CVS version
the 'nadgrids: conus' datum parameter line must be added explicitly instead of
the dx: dy: dz 3-parameter transformation parameters. But this can be fixed by
running the latest g.setproj

Paul