could be obtained. Laser scanning presents options that previous methods do not allow. Damaging parts surfaces because of contact is not a problem with laser scanning.A B-spline surface is a parametric surface and needs a parametric domain. The methods were proposed to parameterize a triangular mesh and unorganized points respectively for a single surface patch [1,2]. A single B-spline patch can only model surfaces with simple topological types such as deformed planar regions, cylinders, and tori. Therefore, a single non-degenerate B-spline can't model general closed surfaces or surfaces with handles. Multiple B-spline patches are needed for arbitrary topological surfaces; however, some geometric continuity conditions must be met for adjacent patches. Therefore, B-spline is not the most desirable approach since it requires high-dimensional constrained optimization. A subdivision surface scheme such as loops, which does not suffer from these problems, has compact storage and simple representation (as triangle base mesh) and can be evaluated on the fly to any resolution with ease.In reverse engineering, many researches are focused on converting a large measured point cloud into a CAD model [3]. First, generally, a triangular mesh is created, which 'carries' the data points and reflects the basic topology of the final model. The next step is segmentation in which the point data is partitioned into smaller point regions, so that later each region can be well approximated by a single surface, thus the pre-images of the faces are obtained. Finally, the individual surfaces are trimmed and joined together while assuring fairness and consistency. Segmentation and surface fitting are strongly interrelated as a 'chicken and egg' problem. If the region were known, it would be reasonably simple to find the best approximating surface. On the other hand, if the surface were known, one could collect all points within a given threshold to that surface, and declare this set of points as the region belonging to the surface. In practice, unfortunately, neither case holds. To overcome the problem, this paper focuses on processing of the point cloud data to obtain the necessary information for reconstructing the CAD model of existing objects.To rebuild the CAD model excellently and correctly, a semi-automated approach is applied in feature extraction from the slice data.Abstract A new approach to feature extraction for slice data points is presented. The reconstruction of objects is performed as follows. First, all contours in each slice are extracted by contour tracing algorithms. Then the data points on the contours are analyzed, and the curve segments of the contours are divided into three categories: straight lines, conic curves and B-spline curves. The curve fitting methods are applied for each curve segment to remove the unwanted points with pre-determined tolerance. Finally, the features, which consist of the object and connection relations among them, are founded by matching the corresponding contours in adjacent slices, and 3...

This paper proposes an analytical model of multiple tools selections for machining polygonal surfaces in terms of least machining time. Begin with retrieving a set of cutting-tools from the database and checking the feasibility of using it to machine the pocket, then the dynamic programming approach is applied to determine the possible multiple cutting tools combinations. For each cutting-tool, the corresponding feed-rate can be determined based on the database of cutting-tool knowledge and the machining cutter-path may be generated, and the area covered by the cutting-tool and the unmachined area can be obtained. When the cutter-path length associated with using a specific cutting-tool size has been determined, the processing time can be calculated using the feed-rate that was used. Our approach to calculate the unmachined areas and to generate the cutter-paths is based on an improved scanline filling approach. Based on this information, an optimal set of cutting-tool sizes that minimizes the total processing time for the polygonal surfaces will be identified. Finally, the proposed method has been verified by several experiment results.