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Partiview on GeoWalls

This assumes you know how Partiview works on a regular single screen computer (if not, go here), and you want to know how to convert your .cf files to work on a GeoWall.

This is useful for making things like Hayden's nifty Digital Universe work on a GeoWall.

At the start of your .cf file, place this command

  eval detach full

At the end of your .cf file, place these commands

  eval focalpoint on
  eval stereo -0.005 crosseyed

If the left-right orientation of your GeoWall is opposite to ours, then use some positive number instead of -0.005 in the stereo command.

The magnitude of the number in the stereo command controls the amount of eye separation. Increase it if the image seems too flat, decrease it if your brain finds it hard to put the left-eye and right-eye views together.

The focalpoint command changes the focal distance to be always equal to the distance from the observer to the focal point. By default the focalpoint is (0,0,0), which is suitable for most things. It can be changed to (x0,y0,z0) by the command "focalpoint x0 y0 z0".

Focalpoint was added by Stuart Levy in April 2004. It is therefore not available in the binaries available from Hayden's Digital Universe site as those are from December 2003. Here are binaries for Windows and Linux (right click and save).

If you have trouble running them (or want to use Partiview for OS X), you'll have to check out the CVS version - literally. To do so, follow these instructions from Stuart:

cvs -d :pserver:anonymous@cvs.astro.umd.edu:/home/cvsroot -z1 checkout partiview

Note that to compile Partiview you'll also need FLTK 1.1.x, from fltk.org.


For the record, here's the story of focalpoint. Mark SubbaRao, who had been using Partiview on GeoWalls since late 2002, had long realized there was a problem with how it did stereo. This was because he was using it to fly through SDSS data, a process that went through several orders of magnitude of scale changes. In March 2004, he found that changing the focal distance with camera position helped. In April 2004, Dinoj Surendran (who had begun working with Mark in late 2003) noticed a pattern in the changes, and emailed Stuart Levy asking if Partiview could constantly change the focal distance to equal the distance from the camera to the origin. Stuart liked the idea, and promptly added a feature to make it possible without any perfomance hit.