Map Projections

From: "R.A.Sanderson" <R.A.Sanderson@newcastle.ac.uk>

Is there a simple way of using two map projections simultaneously in GRASS?
I have a GRASS location in UTM, but need to add new maps by digitising
from base maps stored as latitude-longitude. The v.digit command only
seems able to cope with digitising using the same projection as the
original location (in this case UTM). I could resort to using Arc/Info for
digitising, then PROJECT/TRANSFORM into UTM before exporting to GRASS, but
I'd prefer to carry out the whole operation in GRASS if possible.

Yes, use the v.proj command to project your utm location to lat/long

Usage:
v.proj map=name [out=name] inloc=name [dbase=name] [set=name]

Parameters:
    map input vector file name
    out output vector file name
  inloc Location containing INput vector map
  dbase Database containing INput location
    set mapset containing INput vector map

You can also use v.proj to shift your datum from nad27 to nad83. Just
create a file called DATUM_INFO under your PERMANENT mapset. The file
contains 2 lines:

datum: nad27 or nad83
region: conus

v.proj is a contributed command under the src.contrib/SCS/mapdev/v.proj
directory.

Jill
__________________________________________
     ____ __ ______ _____ _______ .
      / \ // / // / // // // / \
     / \ // / // / // / \
    / \ // /____// / //____/// /.....\/\ /\
   / \// / \\ / // / \_/\_/ \
_/ \/__/ \\_/_____//______ // /\/ _/\ ---------
________________________________________/

Jill R. Schuler
USDA
Natural Resource Conservation Service
2627 Redwing, Suite 120
Ft. Collins, Co 80526 FAX: (970) 282-1930
            VCOMM:9010-2418
e-mail: jschuler@itc.nrcs.usda.gov Phone: (970) 282-2418

Jill,
I don't believe that the datum transformation option ever made it into
the CERL release of GRASS (someone correct me if I'm mistaken). Can you
supply the source for that? Thanks,
  -Malcolm

On Fri, 13 Jun 1997, Jill Schuler wrote:

>From: "R.A.Sanderson" <R.A.Sanderson@newcastle.ac.uk>

>Is there a simple way of using two map projections simultaneously in GRASS?
> I have a GRASS location in UTM, but need to add new maps by digitising
>from base maps stored as latitude-longitude. The v.digit command only
>seems able to cope with digitising using the same projection as the
>original location (in this case UTM). I could resort to using Arc/Info for
>digitising, then PROJECT/TRANSFORM into UTM before exporting to GRASS, but
>I'd prefer to carry out the whole operation in GRASS if possible.

Yes, use the v.proj command to project your utm location to lat/long

Usage:
v.proj map=name [out=name] inloc=name [dbase=name] [set=name]

Parameters:
    map input vector file name
    out output vector file name
  inloc Location containing INput vector map
  dbase Database containing INput location
    set mapset containing INput vector map

You can also use v.proj to shift your datum from nad27 to nad83. Just
create a file called DATUM_INFO under your PERMANENT mapset. The file
contains 2 lines:

datum: nad27 or nad83
region: conus

v.proj is a contributed command under the src.contrib/SCS/mapdev/v.proj
directory.

Jill
__________________________________________
     ____ __ ______ _____ _______ .
      / \ // / // / // // // / \
     / \ // / // / // / \
    / \ // /____// / //____/// /.....\/\ /\
   / \// / \\ / // / \_/\_/ \
_/ \/__/ \\_/_____//______ // /\/ _/\ ---------
________________________________________/

Jill R. Schuler
USDA
Natural Resource Conservation Service
2627 Redwing, Suite 120
Ft. Collins, Co 80526 FAX: (970) 282-1930
            VCOMM:9010-2418
e-mail: jschuler@itc.nrcs.usda.gov Phone: (970) 282-2418