[GRASS-dev] Re: [GRASS-user] create a xy location with g.proj

[Maciej Sieczka]

Hamish wrote:
>> Peter Löwe wrote:
>>> does anybody have an example how to create a xy-location using g.proj
>>> -c ?
>>>
>>> Calling up g.proj from within a xy-location using the -j/-w flags (to
>>> create output in wkt/proj format) results in the info "xy location
>>> (unprojected)". This doesn't really help.
> 
> Michael Barton wrote:
>> AFAIK, you cannot create an xy location using g.proj. g.proj is for
>> creating projected locations. xy is not projected. When I wanted to
>> create an xy location for the new wxPython location wizard, I had to
>> code it myself. That said, it's not hard to create the WIND, etc files
>> for an xy location.

> If this doesn't exist, then we should look at adding the functionality.
> 
> for example:
>  g.proj -c location="newloc" wkt=none
> or
>  g.proj -c location="newloc" wkt=XY
> or
>  g.proj -c location="newloc" wkt=unprojected

It's a good idea IMO. But I'd suggest not to mix WKT with
this - WKT has it's strict meaning (there's no WKT
representation for GRASS XY location settings AFAIK; is
there?). Moreover, wkt= parameter is supposed to be a file.
How about this: if -c is used and no wkt, georef or proj4
parameters are given, assume XY?

BTW, I noticed a following sentence in g.proj manual
regarding georef option: "If the file is not georeferenced
or cannot be read, XY (unprojected) will be used". But it
does not work:

(file xy does not exist):

$ g.proj -c georef=xy
Trying to open with OGR...
Trying to open with GDAL...
ERROR 4: `xy' does not exist in the file system,
and is not recognised as a supported dataset name.

ERROR: Could not read georeferenced file xy using either OGR
nor GDAL

(file xy is empty):

$ touch xy
$ g.proj -c georef=xy
Trying to open with OGR...
Trying to open with GDAL...
ERROR 4: `xy' not recognised as a supported file format.

ERROR: Could not read georeferenced file xy using either OGR
nor GDAL

Maciek