Data Acquisition And Feature Analysis For Building Geometric Deformation Based On Image

Nowadays, in an information age, with the need of building digital city, it has become increasingly urgent for getting a lot of three-dimensional models of buildings with the contact-free automatic extraction technology. In recent years, significant research has been concentrated on building recognition, extraction, and3D reconstruction. But there have existed big differences for those research in many aspect including the versatility, automation, data sources, geometric modeling technology, extraction strategies etc. Among those research,the space data acquisition sources include direct access such as measuring robot, photogrammetry,3D laser scanning and INSAR technologies in a hand, and indirectly data acquisition including high-resolution satellite remote sensing images,2D GIS map data, digital surface model of DSM, etc in a other hand.Because of the method of close-range photogrammetry has many characteristics such as low cost, flexible acquisition object and diversification of data processing means, it would be the main research methods in this article. The main work in this article is introduced as follows:Several technologies based on non-contact measurement mode and their application on engineering-oriented surveying has been presented, and the feasibility and technical characteristics on how to use digital imaging with RTS or GPS technology for building feature point surveying also been analyzed. It has been proved that non-contact surveying method based on the buildings feature point extraction is a practicable tool to acquire the data which is used for structure deformation monitoring, and is better means of monitoring technology than traditional one’s including in the work efficiency, comprehensive, easily-to-automation. Aimed at project structure deformation monitoring problems, this paper takes advantage on digital photogrammetry, combining with the RTS, GPS and other surveying technologies, analysis in multi-views on the possibility of using image data to monitor project deformation including the selection and optimization of image control network, image data resolution, analytical photogrammetry technology used in object-oriented deformation monitoring and so on. The products based on coordinates of3D building include all types of data used for deformation monitoring and analysis, structure graphics and images, digital surface models(DSM) and3D dynamic deformation simulation. All of which have been carried out through various projects. One of spatial data acquisition integrated technology by non-contact surveying method proposed by this paper mainly analysis the characteristics of close-range image used in buildings feature extraction, including the use of photogrammetry projection transformation, pattern recognition, image processing, and other key technology in the image analytic processing. It has been put forward with the application of mathematical morphology method in generating new images with feature extraction, edge detection of the building which could provide a means of extracting feature point and line from building with semi-automatic even automatic way. According to the experiments of elevation surveying for the Foreign Trade Office building of Liaoning province, it has been proved to be an effective and an economical measure in building elevation surveying which are based on the method of multi-district control proposed by this paper. It can be done by combining ordinary surveying instrument with non-topographic camera. A model has been set up which could be used to obtain the space coordinates of feature points distributing on building with the non-contact surveying.The use of images backward intersection and forward intersection alternate adjustment under the RTS control could be used to acquire geometry spatial distribution for large-scale steel grid, and through repeating data acquisition at different station and different angles in same node points(check points), it has been proved that the mutual difference acquired by3D coordinates meets the precision requirements for testing surveying.With regard to the calculation in high-precision for deformation, the problem is aimed at the solution instability led by weak correlation between norm equations (or the distribution between control point is not very good), quick algorithm for orthogonal GIVENS transformation to improve the quality of the solution has been adopted in the paper, and its testing data in the experience of ship-lock deformation has been carried out.As for closing range photogrammetry, it is important to improve the precision of image points when considers some key factors such as the selection of camera station and photography method. The distribution of control points and the procession of image data analysis etc. L-estimates theory is been proved an effective method to diminish or eliminate gross error of image points. Combining the practice of ship-lock deformation,it is shown that the solution result has been improved effectively when using L-estimates under different condition. α-Trimmed Mean (Belong toL-estimation) has been proved an efficient algorithm in picking gross error out. When the condition of constitute network with control points is poor, the adjustment results by using L-estimation is better than the LS results.As for the measurement of steel-net engineering structure, the idea of analytical photogrammetry based on the initial value of the image with DLT has been proposed, as well as how to establish TIN models when the object of three-dimensional steel grid would be reconstructed. In particular, it has some value in establishing grid structure TIN by using gradually insertion for grid unit area.Based on control network units, combining the remote total station with digital camera, we can obtain the distribution of steel nodes and deflection curve of steel grid structure easily, the measurement result shows that this method is effective and utilitarian.With the means of image motion parallax while combining the modern surveying technologies such as GPS, RTS, dynamic and static deformation data acquisition has been carried out with the aim of studying building deformation according to different object feature points. Analysis the static and dynamic deformation characteristics which are based on the data acquired from spatial image with motion parallax, it has proved that this method is a useful means for engineering structures health detection. Testing in the Bei-da Bridge health detection shows that the monitoring data acquired by non-contact method such as GPS, RTS and image motion parallax reflect the change of deflection geometric characteristic when the loading on bridge is changed.The result studied in this paper could provide a new way for building feature point surveying and engineering structures deformation monitoring, and has a certain degree of theoretical and practical significance.