This work was supported by the NSF Grant ECS 81-19886. The work was also supported in part by CIDMAC, a research Unit of Purdue University sponsored by Purdue, Cincinnati Milicron Corporation, Control Data Corporation, Cummins Engine Company, Ransburg Corporation and TRW.


An algorithm has been designed to construct the CSG model of object from its 2D orthographic projections. The method proposed uses a top-down approach in which the existence of some 3D primitive (e.g. CUBE) is assumed and then different views are searched for appropriate elements to prove the assumption .The algorithm is applied to some examples and the results are demonstrated. A second algorithm has also been designed to implement the automatic input of line drawings. The drawings are first digitized using a high resolution scanner. After some preprocessing, the algorithm is applied to the image in order .to extract the relevant graphical elements, such as arcs and circles. Two examples are also demonstrated.

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