Research On The Relate Technology Of Continuous Surface-surface Intersection For Sculptured Solid Modeling System

Surface/surface intersect algorithm (SSI) is the kernel and key algorithm of solid modeling in computer aided design. This dissertation makes scientific researches on continuous surface intersect, at the same time, it presents algorithm and data structure to support the continuous Boolean operation.The dissertation reviews the history of solid modeling, it analyzes general SSI algorithm, and summarizes background of continuous SSI.Offset surface and motional surface play important role in CAD/CAM. In some time-critical situation, Continuous SSI is computation bottleneck of some solid modeling system. Conventional approach for solving continuous SSI often uses intersection algorithm iteratively without taking the characteristic of the surface into account to simplify computation. The dissertation analyzes the intersect curve structure of continue surface, from the point of intersect curve's evolution, it describes the relationship between topology of offset surface intersect curve and topology transmit point (TTP). It presents algorithms to extract the similarity of intersect curve in different offset distance and use TTP to label the topology of surface intersect. The algorithms succeed in combination of tracing method and topology information, and present an optimized offset SSI algorithm. The optimized algorithm pre-processes surfaces to achieve TTP, and decides calculation strategy of starting points by analyzing the properties of TTP on the surface. According the topology of intersect curve, it dynamically adjust the local tracing strategy to reduce the SSI computation time. It can overcome the degenerate conditions such as loop leaking and singularities.Based on offset SSI algorithm, the dissertation pay emphases on motional SSI problem. It uses properties of motional surface to find the TTP, and proposes an optimized motional SSI algorithm. The algorithm also can reduce computation time and overcome the degenerate conditions.After analyzing general data structure of curved solid modeling, it proposes a Boolean operation algorithm for motional curved solid modeling, the goal of algorithm is to ensure effectively robustly and accurately. The topology and geometry of solid is represented by trimmed curve surface and half-edge data structure. It applies the continuous SSI mentioned above to motional solid Boolean operation, and uses the similarity of intersect curve to simplify SSI problem, it can save computation time. At the same time, hierarchy intersection is applied for unified classification, and for tracing the intersection curve to overcome degenerate cases that occur frequently in practice. The dissertation also extends it to Boolean operations for non-manifoldttmodels.To meet the demand of some time-critical situation, the dissertation presented a distributed algorithm for Boolean operations of curved solids. The main work of the algorithm extracts the parallelism at all stages, and a dynamic load balancing strategy is used, allocates works to different computation knot in local network. It implements a distributed motional curved solid Boolean operation in local network. The dissertation modifies the above algorithm to support motional Boolean operations of curved solid.