Automatic Generation of 3D CAD Models

Abstract We present an approach for the reconstruction andapproximation of 3D CAD models from an unorga­nized collection ofpoints. Applications include rapidreverse engineering of existing objects for usc in asynthetic computer environment, including computeraided design and manufacturing. OUf reconstructionapproach is flexible enough to permitinterpolation ofboth smoothsurfaces and sharp features, while plac­ing few restrictions on the geometry or topology ofthe object.Our algorithm is based on 3D Delaunay triangu­lations and a-shapes to compute an initial trianglemesh approximating the shape ofthe object. A meshdecimation technique is applied to the dense trian­gle mesh to build a simplified approximation, whileretaining important topological and geometric char­acteristics ofthe model. Thereduced mesh is interpo­lated wit.h piecewise algebraic surface patches, whichapproximate the original points.The resulting model is suitable for typical CADmodeling and analysis applications. 1 Introduction

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