georeferencing

[Wang Song]

> From grass-lists-owner at max.cecer.army.mil Tue May 11 21:48:22 1993
> Date: Tue, 11 May 1993 19:23:20 -0700
> From: alicia at deepthought.ucdavis.edu (Alicia Palacios)
> Sender: lists-owner at max.cecer.army.mil
> Reply-To: grassu-list at max.cecer.army.mil
> To: info-grass-user at ux1.cso.uiuc.edu
> Subject: georeferencing
> Content-Length: 439
> 
> 
> I have a raster file and a vector file from a scanner, they are in
> x,y coordinates.What is the way to import this files in grass in a mapset
> already georeferenced to UTM?
> It is possible to georeference to utm coordinates inside of grass,
> or it is necessary to import the files with the correct coordinates?
> Also, is it possible to import a dxf raster or it should be a vector?
> Thanks for your help.
> Alicia.
> alicia at deepthought.ucdavis.edu
> 

To bring a scanned raster or vetor file into GRASS to georeference it, you 
should create a X-Y GRASS LOCATION first, then load your ungeoreferenced 
data into this LOCATION. After this new LOCATION is created, use i.target to
link this ungeoreferenced LOCATION to an existing georeferenced LOCATION (UTM,
etc.), followed by i.points to interactively select ground control points on 
the scree and build transformation matrix. The last step is to use i.rectify 
actually georeferencing the scanned image (raster file).

Wang Song
wang at cast.uark.edu