<title>Three-dimensional line-scan intensity ratio sensing</title>

Abstract

In this paper we describe a new 3-D imaging technique using a line-scan camera. The technique is based on the Intensity Ratio Sensing principle that was first introduced by J. Schwartz in 1983 [11 [21 [3], In this technique a 2-D image of the scene is acquired twice, each time with a different illumination profile. It is shown by Schwartz that if the two light profiles are created by sources emanating from essentially the same direction, the 3-D image of the scene can be reconstructed from the ratio of the gray levels in the two images. The two light profiles can be created, for example, by using a single light source and filters that can be mechanically switched.* Using a sawtooth type ffluminat.ion [3] alleviates somewhat the problem but does not solve it. Also, more than two views are necessaiy for an unambiguous 3-D reconstruction and thus speed has to be sacrificed.