Table I.

Tracking experiments. The first two columns represent the mean distance that each corresponding ball moved between trials. The last column presents the difference between the range scanner and OPTOTRAK distance measurements of corresponding fiducials. The depth range spanned most of the scanner’s working field of view, with a minimum depth of 493.1 mm and a maximum of 1035.6 mm.

	Mean distance of fiducial movement between sets		Difference of corresponding fiducial distances between range scanner and OPTOTRAK (max)
	Range scan, mm	OPTOTRAK, mm
Near to middle	154.0±0.6	154.0±0.4	0.4±0.2 (0.8)
Middle to far	220.7±5.7	220.7±5.6	0.4±0.3 (1.0)
Near to far	374.6±5.4	374.6±5.2	0.8±0.6 (1.7)