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Raw point data collected by 3D scanning techniques are usually rendered by building an interpolating robust polygonal mesh. This approach is accurate and fast but provides no means for large scale subsequent modifications. Only local interactive or non-interactive tools are provided that are usually targeted to correcting small imperfections and eliminating noise effects. CAD applications require robust and editable CAD models to support processes such as reproduction, design modification and redesign. In this paper we present a curve approximation method used in a feature-based approach to building feature-based CAD models from 3D point clouds. This approach is based on discovering features on the point cloud by detecting local changes in the morphology of the point cloud. This results in a number of regions that represent object features. The boundaries of the features are approximated by a collection of piecewise cubic rational Bezier curves that best fit the detected border point cloud and are G1 continuous.

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Current trends in free form editing suggest the development of a new novel editing paradigm for CAD models beyond traditional CAD editing of mechanical parts. To this end we wish to develop accurate, robust and efficient 3D mesh deformation techniques such as 3D structural morphing.In this paper, we present a feature-based approach to 3D morphing of arbitrary genus-0 polyhedral objects that is appropriate for CAD editing. The technique is based on a sphere mapping process built on an optimization technique that uses a target function to maintain the correspondence among the initial polygons and the mapped ones while preserving topology and connectivity through a system of geometric constraints. Finally, we introduce a fully automated feature-based technique that matches surface areas (feature regions) with similar morphological characteristics between the two morphed objects and performs morphing according to this feature correspondence list. Alignment is obtained without user intervention and is based on pattern matching between the feature graphs of the two morphed objects.

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