Epipolar reconstruction of 3d structures

Abstract

A method of reconstructing selected features of a part manufactured according to a CAD model involves acquiring a set of linear push broom (LPB) projection images of the part acquired at different angles about an axis of rotation passing through the part. Acquiring a set of matrices M.sub.j j=1 . . . N, each of which maps 3D coordinates of the part to screen coordinates of one of the projection images. Reconstruction of 3D structures from the projection images requires identification of screen coordinates of each image which correspond to a point of the structure of the part to be reconstructed. Back projecting these screen coordinates modified by the distortion inherent in the LPB imaging device. This is accomplished by selecting a screen coordinate on a feature desired to be reconstructed. Computing a ray passing through the selected screen coordinate through an imaging center. Using each M matrix to map this ray to a hyperbola on the other images. The hyperbola is then scanned until the desired feature is encountered. This second screen location of this projection image corresponds to the first selected screen location. A second ray through the second screen coordinate is constructed. Where it intersects the first ray identifies the 3D reconstruction point. This is repeated for a number of points to create a reconstruction of the selected feature.