[GRASS-dev] problems with datum parameters tables

[Michael Barton]

On Oct 16, 2009, at 10:24 AM, Glynn Clements wrote:

>
> Hamish wrote:
>
>>> After selecting the projection in the wizard, you go to a
>>> new page. Currently, if the projection is UTM, you get to
>>> select zone and hemisphere. If it is not UTM, you don't get
>>> to select any parameters. The UTM selection is hard wired
>>> into the GUI.
>>>
>>> I'm changing this so that the the parameters parsed from
>>> proj-parms.table appear for whatever projection is
>>> chosen--UTM or otherwise.
>>
>> LL, UTM, and STP are not real projections so hardwiring them
>> as exceptions wouldn't be cause for alarm; but ok, if a single
>> method does the trick then no complaints from me...
>
> In particular, I would suspect that using PROJECTION_OTHER for a UTM
> projection may confuse either GRASS or the user. E.g. there are many
> places where PROJECTION_UTM causes cellhd.zone to become relevant.
>
> OTOH, we might want to consider changing this. There isn't anything
> inherently special about UTM; it's not like switching zones is any
> different to other projection changes.
>
> Really, there only needs to be 3 PROJECTION_* options: XY, LL and
> OTHER. UTM and STP should ultimately be assimilated into OTHER.
>
> --  
> Glynn Clements <glynn at gclements.plus.com>

I don't know how this works in the underlying C code, this all can be  
handled in a single method that parses proj-parms.table except for  
State Plane. I can see why you call latlon a pseudo projection, but  
not UTM. AFAICT, it is a legitimate projection like the others.

Michael