[GRASS-user] Stereoscopic images

[Michael Perdue]

Morten,

I have experience with softcopy photogrammetry workstations and have  
done some searching for open source software related to  
photogrammetry with out much luck.

As several people have already mentioned, there is E-FOTO which is an  
open souce project and appears to support hardware stereo as well as  
anaglyph viewing. Unfortunately, I can't read Portuguese so I don't  
know much about it.

OSSIM is capable of reading an exterior orientation and camera  
calibration files to generate Orthophotomosaics, but it doesn't have  
a auto-correlation routine for the automated extraction of DSM's nor  
is it capable of viewing image pairs for stereo viewing.

There is a free , but not open source, program called hypercube. It  
does allow for viewing stereo models in anaglyph mode and has a auto- 
correlation routine for the automatic extraction of DSM's, but it  
requires a RPC model rather than the exterior orientations and camera  
calibration file that are normally used with aerial photo's. It  
doesn't allow for the generation of RPC files which kind of leaves  
you SOL unless you have another means of generating these types of  
files. I am unfamiliar with the Rational Polynomial Coefficient  
method of sensor modeling so I don't know if it is possible to  
georeference an image in this fashion with open source software.
http://www.tec.army.mil/Hypercube/

There are no open source or free software programs that I have been  
able to find and work that allow one to perform aerotriangulation.  
The USGS still distributes the source code for a package called AT  
SYS321. It a a bunch of old programs written in fortran that were  
originally written for Aviion Unix based platform (I've never even  
heard of that one). I tried to get them to compile once and quickly  
abandoned the effort without much success. Doesn't look like and  
development has been done on them in a very long time so resurrecting  
such a program is probably more work that it is worth.
http://mcmcweb.er.usgs.gov/atsys/atsys.html

As far as commercial solutions go.... there are several. But you may  
want to slip some Nitro under your tongue before you ask how much  
cause a sophisticated high end softcopy workstation will cost you  
your first born child. The least expensive system I know is LISA-foto  
mated with BLUH aerotriangulation package. a licence is 10000 euro's  
but you can get one for half that if it's for academic purposes.
http://www.ipi.uni-hannover.de/lisa/

If I recall correctly PCI geomatica with the OrthoEngine Airphoto  
models, OrthoEngine productivity tools, Automatic DEM extraction and  
OrthoEngine Stereo support will run around 20000US (errrr.... I think).

To move into a full function high end system like the software  
produced by inpho GmbH, BAE Socet Set or Z/I imaging, (Take nitro  
now) your looking at around 50k plus hardware for one seat. We use  
products from inpho GmbH and can vouch for their quality.... as well  
as their cost.
http://www.inpho.de/
http://www.intergraph.com/photogrammetry/
http://www.socetgxp.com/

To view in Stereo you do need special hardware. AFAIK they all  
require CRT monitors and such monitors generally need to have a  
refresh rate of at least 120Hz at the desired resolution. The  
graphics cards need to be quad buffered which means that you're  
looking at the pro series cards such as ATI Fire GL cards, Wildcat  
and NVIDIA Quadro series. Finally you need LCD shutter glasses (~ 
$1000) or polarizing panels (~$2000).
http://www.reald-corporate.com/scientific/

However, different systems may have a limited number of supported  
cards so it's best to chose your software and then go with whatever  
platform they recommend.

Hope this helps more than it discourages.

Cheers,

Mike


On 29-Jun-07, at 4:56 AM, Morten Sickel wrote:

> I am involved in a project using aerial photographs, earlier we have
> been using dias and an 'old fashioned' stereoscope for  
> interpretations.
> Now we are to get the pictures as files. What kind of hard- and  
> software
> do we need to view stereoscopic images on screen? Is this possible
> within grass / ossim or otherwhere in the free software family? Do we
> need to get some special hardware, or is is possible to calculate the
> heightinformation from a couple of georeferenced images and then  
> use eg
> nviz? Does anyone here have any experience on that kind of work?
>
> Morten
>
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