Fringe Code Reduction for 3d Measurement Systems Using Epipolar Geometry

In this work a new approach for code reduction for fringe projection 3D measurement systems is introduced. These devices are used for contactless 3D surface measurement with high accuracy. In order to prevent ambiguities in the point correspondences usually Gray-Code sequences are used leading to long recording times. In our approach we use the restriction of the valid measuring volume and epipolar constraints to reduce the valid area for proper point correspondences. This reduces the necessary number of Gray-Code images in the sequence. The inclusion of the epipolar geometry of the projector leads to further reduction of images, and, if the arrangement is especially designed to unambiguousness of the point correspondence excluding the Gray-Code at all. The projection of the fringes approximately perpendicular to the direction of the epipolar lines allows the omission of a second projection direction. First results show that both the completeness and the accuracy of the new method are comparable to the conventional technique. A considerable reduction of the number of recorded images and hence a speed-up of the image recording time can be achieved.