Comparison of Passive and Active Fiducials for Optical Tracking

The paper analyses the constraints related to optical tracking of an HMD with a single commercial binocular stereoscopic optical tracking system and offers an overview of different factors affecting the best active fiducial set-up and marker geometries for reliable tracking with a focus on the rotational accuracy of a marker.

Two IR diode models with different emission characteristics were tested as active fiducials and the results were compared to localization accuracy of passive fiducials. In terms of preferable marker geometry, it was found that the area enclosed by the fiducials should be maximized. Thus, due to geometrical constraints, very small marker geometries may not be stable or feasible entirely. Rotational accuracy was analysed for cases when the marker was not directly facing the tracking device and it was found that rotation about one axis introduced errors to the determined orientation in space related to the other axes as well.