Recovering 3D motion and structure from stereo and 2D token tracking cooperation

An investigation is conducted of the relationships that exist between the three-dimensional structure and kinematics, of a line moving rigidly in space and the two-dimensional structure and kinematics (optical flow) of its image in one or two cameras. The authors establish the fundamental equations that relate its three-dimensional motion to its observed image motion. They then assume that stereo matches have been established between image segments and show how the estimation of the optical flows in the two images can be used to compute part of the kinematic screw of the corresponding 3-D line. The equations are linear and provide a very simple way to estimate the full kinematic screw, if several lines of the same object are available. Experimental results using synthetic and real data are presented