[GRASS-user] question on georectification

[Maciej Sieczka]

Harri Kiiskinen napisał(a):
> ma, 2006-07-24 kello 19:58 +0200, Wolfgang kirjoitti:
>> Hi,
>>
>> I've scanned some maps but as my scanner is not big enough I had to scan 
>> each quarter on its own. I've imported these scans into a xy-location. 
>> Can I use i.group to group these 4 scans together and then i.points to 
>> get directly the full map? Or do I have to project the scans 
>> individually and to combine them after rectification?
> 
> I did the latter and the results were not too good; even though using 10
> to 12 control points, the overlapping parts did not sit together too
> well. And you have to create a separate location for each scan (logical
> though not intuitively apparent).

Why so? I don't think it is necessary. You can import each unrefferenced
scan into the same xy location and process each scan individually.

You might like to take a look at recent Hamish'es scipt, i.warp61,
http://grass.gdf-hannover.de/wiki/GRASS_AddOns#Imagery_add-ons.

> 	Were I to do it now, I probably would start by combining the scans
> together with a program like Hugin (http://hugin.sourceforge.net/). It
> has performed well in joining partial scans of large drawings for me,
> and the tutorials do have a nice example of just this kind.

Cool indeed!

Maciek