[GRASSLIST:1803] Re: i.ortho.photo on osx

[Ian Macmillan]

Richard, thanks for your response. If you had a similar experience, I am pretty
curious to know what happened.  I am not sure that I have a feet to meters
problem though.  I am projecting from an XY location into an UTM projection. 
The dem elevation units are in meters.  I projected my dem from a lat-long
location, however the elevation units were meters in that too.  If it isn't
much trouble, I would be curious to see what your case is.

Thanks, ian



Quoting Richard Greenwood <Rich at GreenwoodMap.com>:

> Ian,
> 
> I ran into some unusual results that looked similar to yours. It was a 
> while ago so I forget the exact details, but I got it working correctly by 
> changing the Z units. My foggy recollection is that I supplied a DEM in 
> meters, but my horizontal units were in feet, and the results were highly 
> distorted. And changing everything to feet produced correct results. I you 
> have not solved your problem yet, I would be happy to resurrect my project 
> and see if I can provide a better description.
> 
> I do not think an elevation range of 540m should be a problem. I had a 
> project with over 1500ft that came out very nicely.
> 
> Both of the projects that I did were on Mandrake Linux, but I doubt that 
> your problems are rooted in OSX.
> 
> Best regards,
> Rich
> 
> 
> At 09:13 AM 11/17/2003, 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?  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?
> >
> >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
> >
> >
> > >
> > >
> >
> >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
> 
> 
> Richard W. Greenwood, PLS
> Greenwood Mapping, Inc.
> Rich <at> GreenwoodMap <dot> com
> (307) 733-0203
> http://www.GreenwoodMap.com 
> 


-----------------------------------------------------
Ian MacMillan
Geological Sciences-UCSB