Finding a picture's station point: reconstructing virtual space when the usual way will not work

To reconstruct the space represented in a photograph or other picture made in perspective, its vantage point, or station point, must first be found, and the usual way to find this point requires that the picture show a rectilinear grid or at least one grid element. The station points of the many pictures that lack any such grid may be found by a new method presented here, on two conditions: The line of sight, from the original observer to the scene, must be determinable, and, within the scene, there must be at least one quantitative spatial relation involving both a depth extent and an extent laterally (breadth or height), the 3-D value of which is known. Researchers may use either the graphic (projective) or the computational (algebraic) procedures of this new "sightline" method, in reconstructing the spaces of pictures used as stimuli.