Measurement in three dimensions by motion stereo and spherical mapping

A motion stereo algorithm for measuring straight lines three-dimensionally is presented. The three-dimensional information is obtained by moving a single camera linearly and processing the resulting sequential multiple images. The algorithm utilizes spherical mapping, which is a transformation from a point to a great circle on a sphere. This algorithm makes it possible to process an image from a fisheye lens, which has a wide field of view. A straight line composed of several pixels is concentrated at a single point on a two-dimensional image. A three-dimensional image measurement is then performed by use of the above point. This yields high measurement accuracy and reliability. The measurement accuracy can be improved by lengthening the span of the camera movement and by increasing the number of frames. The measurement reliability can also be improved by increasing the number of frames. The basic algorithm is described, and its characteristics relating to accuracy and reliability are tested