| Summary: | 碩士 === 國立中央大學 === 土木工程研究所 === 94 === Terrain representation is one of the most common tasks in visualization of geoinformation. In order to realistically visualize real landscape, several issues have to be addressed, in particular, how to combine terrain meshes and texture images. In this study, Level of Detail (LoD) was applied to both terrain meshes and texture images for producing realistic visualization with better performance but without too much information loss.
Several layers of terrain networks and texture images with different levels of details were created from original high resolution digital elevation model and satellite image using quad-tree and image pyramid algorithms, respectively. These were used as base data for dynamic landscape visualization. During the visualization, visible areas of each scene were determined dynamically from viewing parameters. The scene was created using a block-based composition scheme. The study region was divided into several blocks. To improve the visualization performance, only blocks within the view frustum should be processed. In addition, which LoD to use for each block was determined according to pre-defined viewing distance criteria. Then, selected terrain meshes and texture images were combined and rendered to produce the final visualization scene.
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