Passive ranging using image expansion

This paper describes a passive-ranging technique based on image-plane object expansion as its distance to the moving camera decreases. The motion and shape of a small window, assumingly found inside the boundaries of some object, is approximated by an affine transformation. The parameters of the transformation matrix-expansion, rotation, and translation-are derived by comparing successive images, and progressively increasing the image time separation. The increased baseline results in a triangulation accuracy which is much improved compared to that currently achievable. The algorithm's performance on flight data is presented.