on the camera 39 s film frames defines a known ray from the camera the object surface point must therefore lie on the intersection of the two rays similarly when two projectors illuminate a surface point with coded patterns that are visible to a common camera position it is possible to obtain stereo information from the intersection of the two known rays from the two projectors the ray identification being taken from the unique codes found for each projector at a given point on the film frames in this particular case camera distortion is of no consequence since the camera is only used to obtain the two projection codes present at a particular point in space the information as to the position of the surface point on the film frames can be used with a low distortion camera system to check the assumptions made with respect to projector locations when an assumption of camera or projector position information has an error it is now possible to correct it because the spatial data for a particular point has been derived from several independent camera projector positions more importantly three dimensional data points corresponding to features on a surface can be registered together in a definite manner even though they are arrived at via separate measurement processes this is achieved via commonality of a camera position for two or more projector positions or via commonality of a projector position.