[GRASSLIST:2306] Re: Question about import of non georeferenced image

[Eric G. Miller]

On Tue, Aug 07, 2001 at 10:41:19AM -0700, Rich Shepard wrote:
> On Tue, 7 Aug 2001, Moritz Lennert wrote:
> 
> > You cannot change a region once you defined it. If you want to reproject
> > data into a different projection you will have to create a new location
> > with the desired projection and project from your old location to your new
> > location (r.proj).
> 
> Moritz,
> 
>   Perhaps I'm particularly dense this morning, but isn't the problem more
> fundamental than this? A scanned image has no region, does it? It's just a
> bunch of bits until it is -- somehow -- georeferenced.

It's "region" (or cellhd) has resolution 1x1 and something like:

north = <cols>
west  = 0
south = 0
east  = <rows>

Now, say you know what the X-Y resolution should be, and what the
north/south/east/west values should be (but you didn't have a TIFF World
file) -- you can hack the cellhd file directly.

But, if you only know that info in relation to another data set -- check
out i.rectify and related...

-- 
Eric G. Miller <egm2 at jps.net>