Longuet-Higgins H C
Vision Res. 1986;26(1):181-3. doi: 10.1016/0042-6989(86)90079-9.
This paper discusses a number of points that arise in the visual interpretation of optic flow fields. Particular attention is given to the case in which a flow field is visually ambiguous, and the paper concludes with a detailed description of the case of the moving plane.