In this article we determine the multiplicity of solutions while there are always infinitely many solutions if the feature in several cases where line correspondences from orthographic propoints are obtained by orthographic projection [12].
jections over three views are known. We show that in the general
In this article we determine the multiplicity of solutions in case where the motion may vary between frames, seven line correseveral cases where line correspondences from orthographic prospondences over three views are sufficient to guarantee that in genjections over multiple views are known. Our model will consist eral there is a unique solution for the rotation and directions of the of a single fixed camera with a moving object, although in the case lines, up to a reflection about a plane parallel to the camera plane.
of general motion this is equivalent to having multiple cameras with
There is a three-parameter infinite family of solutions for the translaunknown relative positions simultaneously photographing a fixed tions and depths of each line in this case. If the object is experiencing constant rotation, then four lines are sufficient to obtain solutions up object. It has been shown [13][14][15] that two perspective views are to the same ambiguities. If the object is moving with constant rotation never sufficient to determine motion and structure given line correabout a center of rotation which itself is moving in a straight line at spondences. In a similar manner it is readily shown that the analoconstant velocity, then three lines are sufficient, and there is just a gous result is true with orthographic projections; hence, we will one-parameter infinite family of solutions for the translation and concentrate on situations with three views. depths of the lines. Several examples are given to illustrate our results.
When dealing with perspective projections such as those ob-