We propose a new algorithm to simultaneously recover the motion and 3D
shape of moving objects from feature points of the moving objects in
an orthographic projection. Given the assumption that the moving objec
t is a rigid body, the newly proposed algorithm uses times series corr
espondence of feature point coordinates in the orthographic projection
s and is based on the correspondence of 4 feature points at 3 points i
n time where the existence of a solution has been demonstrated. The me
rit of this algorithm is that it is a linear algorithm for recovery th
at uses only observed data, has the condition of unique recovery solut
ion in principle, and can be applied in a unified manner in the case o
f a unique solution. In this method, after the possibility of recovery
is determined by calculating the rank of the matrix, the recovery sol
ution can quickly be found in a unified manner through a linear comput
ation including matrix inversion computations. This theory solves the
usual problems in the linear recovery theory in the recovery of moving
objects from the point correspondence in orthographic projections and
is segmented in theory. We verified the validity of this algorithm us
ing simulation data generated by a computer, and after obtaining corre
sponding points, verified that real-time processing with an average re
covery time of 4.6 ms is possible even for a personal computer CPU pro
cessing. In addition, the effectiveness of this algorithm was confirme
d by using the real image of a moving object.