i.rectify

[Malcolm Williamson]

On Thu, 25 Sep 1997, Jean-Marc Chofflet wrote:

(deleted lines)

> My first step was to digitize each of the images in CorelXARA (vectorial
> software)
> and try to fit the pieces together : some distorsions were too important
> so I've used
> i.rectify2 under GRASS, then produced 15 rectified images. I've tried
> again under CorelXARA :
> again some distorsions (not the same ones). So I r.patched my rectified
> images to produce
> one image : it works (almost perfectly)! My question is : does r.patch
> do more then just 
> connecting the pieces together or did I misused CorelXARA when I tried
> to join the rectified
> images "by hand"?

r.patch is real simple - it just takes the list of input maps, starting 
with the first one, and copies the data to a new raster layer, with each 
successive map only being able to add data where there was _not_ data 
from an earlier map in the input list. In other words, the first map will 
overlap the second one, the second will overlap the third, and so on 
(assuming that there is a degree of overlap between input raster layers). 
It doesn't adjust the data in any way. Hope that helps,
	-Malcolm

> 
>  Thanks again
> 
> 
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