Patent ID: 7945311

Claim:
A system comprising: an object to be tracked including a first retroreflective marker having a substantially spherical shape comprising a first spherical cap having a first diameter and a second spherical cap having a second diameter greater than the first diameter, the first spherical cap and the second spherical cap being disposed substantially concentric in relation to one another, a split line defining a plane that intersects the caps, wherein the second spherical cap terminates at the split line, a portion of a surface of an outer edge of at least one of the first and second spherical caps having a reflective material, thereby providing retroreflection from the marker; a marker illuminating device configured to illuminate the first retroreflective marker; a marker sensing device configured to detect the illuminated first retroreflective marker and for generating first data indicative of the location of the illuminated first retroreflective marker in space; and a computing device configured to process the first data generated by the marker sensing device to determine a position of the object in space.