[GRASS5] raster georectification

Kirk R. Wythers kwythers at umn.edu
Wed Jan 7 15:42:08 EST 2004

On Jan 7, 2004, at 10:57 AM, Moritz Lennert wrote:
> Why do you need to run i.points three times ? Since they are grouped 
> and
> i.points and i.rectify work by group (you can determine which images 
> in a
> group you wish to rectify), you only have to use i.points once for
> rectifying all images in a group.

Perhaps I am misusing i.group. I started with 6 scanned maps, each of a 
different geographic space representing adjacent townships and ranges 
(essentially a 3X2 matrix of a single larger map). After importing into 
GRASS, I was left with 3 color bands for each map (rgb). All 6 maps 
need to be assembled into a single map with all color bands.  I defined 
a single group with i.group. I now believe that I should have defined 6 
separate groups with i.group (one for each of the 6 geographic 
locations). So the question is: in what order should these steps be 

1. merge rgb bands into a single map for each of the 3 bands
2. georectify with i.points
3. overlay adjacent maps

> It depends of what kind of processing you wish to do and what type of
> image you have.

These maps are hand drawn forest with color pencils (nothing fancy but 
very detailed and of historic significance). I don't want to loose the 
"wow" effect of looking at all the colors together until they get heads 
up vectorized.
Kirk R. Wythers	                                     tel: 612.625.2261
Dept. of Forest Resources                 fax: 612.625.5212
University of Minnesota      email: kwythers at umn.edu

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