Object surface shape and variation evaluation and display - using superimposed photographs of projected images of grids exploiting moire effect

摘要

A device determining and displaying the shape or shape variations of object surfaces projects a grid onto the object and photographs the image of the grid on the object from a direction different from the projection direction. The photograph is superimposed on a similar photograph of a reference object using the Moire effect. The components can all be suitably positioned w.r.t. the object so as not to be adversely affected by it or the measurement path conditions. Objects can be observed in houses with only relatively small openings. The grid is projected from a finite distance onto the measurement object and separately onto the reference object. Both photographs are taken from points at the same perpendicular distance from the object surfaces.