Rekonstruktion von Fassadenstrukturen mittels formaler Grammatiken und Reversible Jump Markov Chain Monte Carlo Sampling
Rekonstruktion von Fassadenstrukturen mittels formaler Grammatiken und Reversible Jump Markov Chain Monte Carlo Sampling
复制标题
形式化语法和可逆跳转马尔可夫链蒙特卡罗采样的法萨登结构重构
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发表时间:
2010
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通讯作者:
Nora Ripperda
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作者:
Nora Ripperda
Three-dimensional building models are used in a variety of applications. These can be found in fields such as tourism, city planning, or 3D navigation. Due to the increasing number of applications, the demand on 3D models is growing. In order to cover the requirements and to keep the data up to date, automatic reconstruction methods are needed. Because the requirements in the level of detail are increasing simultaneously, in this thesis a method for automatic facade reconstruction is developed. For the reconstruction image and depth data are used, which were acquired using a terrestrial laser scanner. In this thesis a new method is developed, which combines a Reversible jump Markov Chain Monte Carlo method with formal grammars. The use of grammar rules and priors, which are derived from relative frequencies, ensures that structural and stochastic attributes of facades are considered likewise. The reconstruction method places special emphasis on the analysis of facade structures. Facade images are analysed to obtain information about the structure of facades. The received information is employed as prior knowledge in the reconstruction process. The knowledge about facades is formulated in a formal grammar. It contains patterns which occur frequently on facades like windows in a grid structure, symmetries or repetitions. If these structures are detected in the data, they can be used for compact storage of the data or for generalisation. The second important issue of this thesis is the development of an automatic reconstruction procedure. This method generates the derivation tree automatically, which fits the data best, using the rules of the facade grammar. In this thesis a Reversible jump Markov Chain Monte Carlo approach is used. This stochastic process proposes a change of the Markov Chain according to the rules of the facade grammar. Depending on an acceptance probability the change will be accepted or rejected. Furthermore, this thesis addresses the determination of the acceptance probability. It is important to ensure a balance between the quality of the fit of model and data and the model complexity. To take this into account a scoring function based on minimum description length is developed. Finally the results of the reconstruction are analysed. The reconstruction method was tested with six data sets consisting of depth and image data and one data set consisting of depth data only. Six of seven facades were reconstructed correctly in structure and position of the facade elements. The correctness and completeness of all reconstructions lies between 95.3% and 88.3%. Additionally the expressiveness of the facade grammar was tested with the aid of a facade image database which contains 56 images. 33.9% of the facades were reconstructed correctly, 21.4% were reconstructed wrong. The remaining 45% show small variations compared to the facade. The correctness of the first group lies between 94.1% and 84.6% and the completeness between 93.9% and 81.8%.