deskconf -- configure tracking for a 1-wall CAVE

deskconf calibrates tracking for a 1-wall (desk) Cave. You can find a gzipped tarred source + CAVElib-2.6-binary package at http://www.ncsa.uiuc.edu/VR/Apps/deskconf.tar.gz.

It prompts for environmental information, invites the user to hold the wand's sensor blob to various points on the screen, and then writes (to standard output) appropriate CAVE configuration commands, suitable for inclusion in e.g. /usr/local/CAVE/etc/cave.config. The only text written to stdout (as opposed to stderr) is valid CAVE config commands, so you could test by invoking as


  deskconf >> .caverc; cavevars

It does write both ProjectionCorners and 2.6's new ProjectionData directives, so the config should work with both kinds of apps.

This version has been tried with CAVElibs 2.5.6 and 2.6. It uses some internal CAVE functions to get the wall name, and to get hold of the library's X display pointer so that it can open X fonts. Both of these internal functions changed between 2.5.6 and 2.6, and may presumably change again. If it breaks, look for code around the #pragma weak statements in the source.

If the tracker's output doesn't appear to be in feet, we emit a non-unit CaveTransmitterRotationMatrix (which scales as well as rotates) to compensate. I don't know whether this is a good idea, but haven't found any bad effects so far.

There's not much provision for internal consistency checking, just:

Deskconf reports (on screen while it's running) what the real-world distances between our three calibration marks should be, assuming that our screen has square pixels and a uniformly-scaled raster (i.e. no linearity error or other distortions), and that they've given us the correct screen width.
Comments in the output mention both the estimated horizontal and vertical scale; if the raster is uniformly-scaled and undistorted, the horizontal and vertical scale should be nearly equal. (The CaveTransmitterRotationMatrix just assumes uniform scaling in all directions, using the horizontal scale factor. This may be a bad idea
You can get a measure of tracker jitter by clicking the middle wand button rather than the left one when marking a point; you can do this several times, and the range of tracker measurements (midvalue +- range) is displayed on the screen. Click the left wand button to go on to the next calibration point.

Stuart Levy, NCSA, slevy@ncsa.uiuc.edu, Nov 1997.