MOIRÉ PATTERNS FROM A CCD CAMERA - Are They Annoying Artifacts or Can They be Useful?

When repetitive high frequency patterns appear in the view of a charge-coupled device (CCD) camera, annoying low frequency Moire patterns are often observed. This paper demonstrates that such Moire pattern can useful in measuring surface deformation and displacement. What is required, in our case, is that the surface in question is textured with appropriately aligned black and white line gratings and this surface is imaged using a grey scaled CCD camera. The characteristics of the observed Moire patterns are described along with a spatial domain model-fitting algorithm that is able to extract a dense camera-to-surface displacement measures. The experimental results discuss the reconstruction of planar incline and curved surfaces using only a coarse 33 lines per inch line grating patterns printed from a 600 dpi printer.