| As an important branch in CAD, AEC(Architecture, Engineering, Construction) is different from mechanical CAD. It has been widely used to improve quality and efficiency of engineering design. Some specific techniques and approaches need to be explored to push forward AEC oriented CAD research and application.AEC oriented CAD is related to many majors. Its global data is huge and local geometric model is simple. The topological modeling methods presented in this dissertation can efficiently represent and manipulate the relationship among engineering objects in large scale product data. The new geometric model of engineering objects strongly support graphic manipulation.The main contributions of this dissertation are as follows,1. The method is presented for applying topological modeling in AEC oriented CAD. First, a hierarchical architecture to represent nodes in topological graph, which includes feature point, line, face and smart solid, is proposed. Second, based on virtual datum, approaches for constraints evaluating for connection and editing for topological graph are explored.2. The implementation of topological modeling in PDSOFT PFD/P&ID, PDSOFT Piping and PDSOFT SteelWorks is presented. Some key algorithms in these software are designed.3. Based on geometric characteristics of engineering objects, a geometric model for engineering objects is proposed, which is represented with faces and contours in memory and with a graphical library and graphical files in storage. The structure of this library and a graphical descriptive language are proposed.4. On the basis of geometric model of engineering objects, a simplified Boolean operation algorithm and a hidden-line removal algorithm are proposed. In Boolean operation algorithm, new concepts such as virtual face and navigating line are used to simplify its implementation. In the hidden-line removal algorithm, concepts such as hiding degree and half hiding degree are presented, which resolve impacts on...
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