|(X,Y)||0.7 pixels||2.1 pixels|
|(0.2% rel)||(0.8% rel)|
|()||4.8 degrees||3.0 degrees|
|(5.2% rel)||(3.1% rel)|
We find RMS errors in pfinder's tracking on the order of a few pixels, as shown in Table 1. Here, the term ``hand'' refers to the region from approximately the wrist to the fingers. An ``arm'' extends from the elbow to the fingers. For the translation tests, the user moves through the environment while holding onto a straight guide. Relative error is the ratio of the RMS error to the total path length.
For the rotation error test, the user moves an appendage through several cycles of approximately 90 degree rotation. There is no guide in this test, so neither the path of the rotation, nor even its absolute extent, can be used to directly measure error. We settle for measuring the noise in the data. The RMS distance to a low-pass filtered version of the data provides this measure.