[GRASSLIST:1783] Re: i.ortho.photo on osx

[Markus Neteler]

On Sat, Nov 15, 2003 at 12:38:05PM -0800, Ian Macmillan wrote:
> Hi all, anyone out there successfully used i.ortho.photo on max os x (jaguar)? 
> I have been having bad luck with it.  I consistently get a weird tiling effect
> with highly distorted images.  A good example can be found here.
> 
> www.uweb.ucsb.edu/~ian_macmillan/calico.tif
> 
> I have a previous post that explains exactly what I did to get this image
> (1702).  As far as I can tell, I have done everything by the book.  Anybody
> have any advice?
> 
> Thanks a bunch
> 
> -ian

Ian,

a similar problem we also face (on Linux, so it's a bug in the i.ortho.photo
library).

Some things to check:
- do you have a DEM which covers the area of the target orthophoto,
  all at the same resolution?
- what's the elevation difference in that area
  (r.univar tells you min and max etc)

We have the impression, that the algorithm is somewhat unstable in regions
with a large elevation range. 

Markus Neteler