1. A system of locating a control object appendage in three dimensional (3D) space, the system including: one or more processors coupled to memory, the memory loaded with computer instructions that, when executed on the processors, implement actions including: recording images of a control object appendage in 3D space using at least two geometrically distinct predetermined vantages; calculating by a processor four co planar tangents to observed edges of the control object appendage from the recorded images; fitting an ellipse by a processor to a cross-section of the control object appendage by selecting the ellipse from a family of ellipses that fit the four co planar tangents using an assumed parameter; repeatedly fitting contiguous cross-sections to the control object appendage; and constructing a model of the control object appendage in 3D space from the contiguous cross-sections.