[GRASSLIST:1779] Re: i.ortho.photo on osx

[Markus Neteler]

On Mon, Nov 17, 2003 at 08:13:41AM -0800, Ian Macmillan wrote:
> Markus, thanks for the response.  I do have a dem which covers the entire
> photo area.  It is a little larger in fact, is that a problem?

That's perfect. It *should* be larger.

> Should I crop it
> so that it is the same size as the photo in area?  The dem is at 10m
> resolution, just like I want the projected orthophoto to be.  I made the DEM
> with s.surf.rst from a 30m dem, doesn't seem like that should make any
> difference from a "normal" dem.  In any case the elevation range is only ~540
> meters.  Is this too much?  What is the biggest elevation range that you have
> gotten to work?  

I cannot tell you right now, have to check first.
 
> The r.univar report for the dem is here:
> Number of cells: 432276
> Minimum: 579.7407226562
> Maximum: 1119.2756347656
> Range:  539.535
> Arithmetic mean:  775.406
> Variance:  17639.4
> Standard deviation: 132.813
> Variation coefficient: 17.1282 %
> 
> 
> Thanks a bunch, ian

Markus
 
> 
> >
> >
> 
> Quoting Markus Neteler <neteler at itc.it>:
> 
> > 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
> > 
> 
> 
> -----------------------------------------------------
> Ian MacMillan
> Geological Sciences-UCSB