基于TIN的公路三维表面模型建立方法

公路三维表面模型是公路三维设计的基础,其关键是设计模型和地表模型的叠加运算。本文提出了一种基于TIN的地面模型和道路设计模型叠加算法,基本原理是把参考模型的边界多边形当作约束边界线插入操作模型,在保持参考模型拓扑关系不变的条件下对其进行局部LOP优化,然后删除位于参考模型边界线内的点和三角形。算法具有实现简单、速度快和运算稳定的特点,已成功应用在公路三维可视化设计中。     

Automatic two-dimensional layout using a rule-based heuristic algorithm

 Efficient layout strategies are introduced for automatic nesting using a rule-based heuristic approach to improve the layout efficiency. Since a large portion of the complexity of the parts layout problem results from the overlapping computation, geometric redesign techniques are also suggested to reduce the complexity of the problem for a fast and reliable means of performing overlapping computation. A new heuristic sliding technique is developed to find a near-optimum layout location from all the feasible arrangements in such a manner that two or more arbitrary parts do not overlap or intersect. An identification method with a pivoting point is suggested to calculate the boundary of the overlap region in a fast computation time-frame. Resource plate clipping using virtual memory, based on a polygon clipping algorithm, is also proposed as a technique to reduce the geometric conditions of the resource plate and the overlap computation time by updating a new stock boundary of the resource plate for the layout space of the next part after each part is placed. The aim of this article is to develop a rule-based heuristic nesting system to achieve a new automatic layout on the AutoCAD system. For this implementation, some nesting examples are demonstrated. A rule-based heuristic approach can be desirable in terms of the layout efficiency and considering the computational time for nesting problems, and is proposed as a real-time layout simulation method in the industrial field. Received: October 7, 2002 / Accepted: March 27, 2003 RID="*"