| Summary: | 碩士 === 國立高雄應用科技大學 === 土木工程與防災科技研究所 === 106 === Compared with the topographic map, the urban large scale digital orthoimage which is obtained by the aerial photogrammetry method is provided with more information, intuitionistic performance, renewed on time, easy to update and widely used, which has gradually become an important part of the digital urban spatial data framework by urban planning, construction, management and land resource utilization applications. With the rapid development of urbanization, urban content is increasingly complex, Traditional orthoimage as a lack of map products has become increasingly prominent, and gradually can not meet the needs of today's application, because of it only consider the undulating terrain without taking into account the buildings and trees and other undulating effects.The real need for true orthoimage is particularly urgent.
The true ortho photo is reconstructed by using the complete three-dimensional digital surface model (DSM) whicth including terrain and feature to eliminate the projection difference, so that both terrain and features are corrected to the correct plane position, and then the hidden area and shadow are effectively detected and repair. The true ortho photo also maintained a direct view of the surface of the landscape which can solve the hidden area because of taller buildings. The production and application of true ortho photo has now become a key issue for researchers.
Compared to vertical photography, oblique photography can capturing more side information, meanwhile the more hidden area it will find. Also because of a large number of images to join the calculation and high inclination and other issues, it’s often resulting in image matching and 3D reconstruction difficulties. True orthoimage production of the core problem is obscured area detection and measurement and compensation of fill and shadow, these key issues directly affect image interpretation and aesthetics。From the research results found that even if the true orthoimage to correct the main measures after the real image of the finished image or there will be some flaws, and these defects directly affect the true radiographic image of the geometric and radiological properties, so this article specifically for the lack of specific improvements of the program. In the TDOM production process at different stages of the problems encountered and improve the countermeasure can be sorted out three parts: in the photographic stage, should first carry out photography planning, by increasing the image overlap rate, cross-carrier and high and low voyage, etc. To reduce the problems caused by shading, and after the acquisition of the image before the need for processing to reduce the difficulty of follow-up processing while improving the production efficiency of TDOM; In the second part, this paper aims at solving the shortcomings of the digital and visual photogrammetry, It is suggested that the optimizing SGM algorithm can be used to solve the problem that the texture repeats and the edge of the object are prone to match the error caused by the semi-global matching of the dense matching of the digital photogrammetry. For the visual photogrammetry (SfM-MVS), the algorithm of optimizing PMVS patch selection is used to deal with the problem of TDOM texture inconsistency; In the last part, the most critical issue for real shot image processing is the elimination of shadows and the hole compensation caused by shading, we recommend that the repair of the holes be based on the example of the effective pixel-based texture synthesis method, for the shadow of the use of the combination of Gamma correction and color space conversion method. This article through the processing of these three programs countermeasures in-depth treatment of all stages of the process, the operation and optimized in order to achieve true orthophoto production process of optimizing.
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