A study on the moire topography - A method for discriminating between the concave and convex regions of an object

The moire topographic method using one grid or two grids is one of the most powerful means for measuring the surface contour of a three dimensional uneven object. But, so far this method has taken no account of the subject of discriminating between the concave and convex parts of an object. In this paper, new equations for the moire topographic method are presented, which contain a new factor for distinguishing between the projection and depression of a body to be measured. Further, in the case of the two-grids method, it is shown that the mismatch method or the grid shifting procedure is an effective means for discriminating between the concave and convex parts of an object, and also that the grid shifting procedure is very useful for obtaining the correct surface contour in the neighborhoods of the top and bottom of an uneven object.