Cliffhanger Walkthrough

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This is a screen-by-screen walkthough to help with setting up the Tracker software for Trackmate with the Portable Plexi Cliffhanger configuration.

Here is what it looks like mounted on the side of a desk.

Notice on the PS3 Eye camera that there are two focal lengths (zoom levels). There seems to be less image distortion on the RED setting, but that also means that you can't have the camera quite as close to the plexi (at least 9 inches away or the image is quite blurry).

Now the Trackmate Tracker application is started. Make sure your camera is fairly square (i.e., not drastically rotated) relative to the plexi surface. Here, the overhead lighting produces a strong glare from above, but this shouldn't matter when tracking since the fairly-uniform lighting from below the table should be mostly what affects a tag's image when placed on the surface.

Next, place a layout guide on the surface (the 9"x7" sheet is shown here). Drag the four corners to match the corners of the guide as closely as possible. The flattened image on the right should show the entire grid (it's okay if the tags don't look square in the "scaled" version of the flattened image).

Pressing [v] shows the tag center likelihood. Unless you chose the 7"x7" layout guide, this view probably doesn't show much. That is because the table size has not been setup yet. Press the arrow keys to match the table width and length with the layout guide size.

At this point, dots should indicate tag centers.

Press [v] again to bring up the data threshold view. Notice that many of the tags look washed out since we haven't calibrated the lighting yet (as indicated by the orange box).

Place a few sheets of white paper on the surface and press [w] to calibrate the white illumination gain.

Place the layout guide back on the surface. The tags should look much more uniformly lit now.

Press [v] again to show the debug view. The Tracker will now try to read tags. For the camera orientation used with this configuration, the Tracker is confused (i.e., not very happy). All of the red regions indicate that the Tracker is trying to read tags but failing completely. The few tags being read here are actually errors -- the Tracker is trying everything to find data and occasionally makes wrong guesses that a valid tag is present (the blue tag centers indicate that it's using tag information from a previous frame, also bogus in this case). The problem is that the image is mirrored so the tag data is being read in reverse order!

To fix the mirroring problem (depending on your setup you may not need to do this step), press [m]. Ahh, much better. :)

Finally, press [v] a few more times until the "fast mode" view appears. This reduces some of the processor load. If you want to save your settings (which will be automatically loaded the next time you start the Tracker), press [!].

The Tracker is now setup and ready to communicate over LusidOSC to other applications.