| Summary: | 碩士 === 國立成功大學 === 測量工程學系 === 89 === Developing a 3D city spatial information system to vividly model a city is currently an intensive research area in the field of digital photogrammetry. In this study area, extracting building information is the most important work. This study proposed a semi-automatic CSG model-based building extraction method to acquire precise, reliable and complete 3D data of buildings.
Designing appropriate building models is a prerequisite of model-based building extraction. Because of the large variety of building shapes, the theory of CSG representation is used to model 3D buildings. CSG is a computer graphics theory that modeling 3D objects with combinatorial primitives. The principle is versatile and easy to understand. In this thesis, how to apply CSG theory for building models and related model operations are illustrated, so that we can apply the CSG models in the semi-automatic model-based building extraction. To investigate how the CSG model fits real buildings, we analyzed and classified the characteristics of common building shapes. Based on the investigation, a CSG building model base containing simple and compound primitives is proposed. By combining the primitives, we can construct complex building models. Each building primitive will be associated with a set of parameters that can be modified to perform model-image fitting. The methods and tests of model operation for model-image fitting will also be introduced.
There are two advantages to establish building model base. First, it defines a rule to simplify building shapes. Second, it transfers implicit information in images into explicit information of buildings. This model-based building extraction approach is developed with the prospects of releasing the operator from tedious point measurements and efficiently delivering precise and reliable results.
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