Convert homogeneous transform to differential motion
D = tr2delta(T0, T1) D = tr2delta(T)
D = TR2DELTA(T0, T1) is the differential motion (6x1) corresponding to infinitessimal motion from pose T0 to T1 which are homogeneous transformations. D=(dx, dy, dz, dRx, dRy, dRz) and is an approximation to the average spatial velocity multiplied by time.
D = TR2DELTA(T) is the differential motion corresponding to the infinitessimal relative pose T expressed as a homogeneous transformation.
D is only an approximation to the motion T, and assumes that T0 ~ T1 or T ~ eye(4,4).