Research on multi-resolution texture model in three-dimensional GIS

Abstract

在三維地理信息系統 (GIS)中 ,影像數據作為模型表面的紋理特征 ,對彌補復雜模型的幾何特性以及提高三維顯示的效果具有十分重要的意義 .為了提高三維模型顯示的速度和效果 ,以及為了降低紋理貼圖時 ,影像的數據量 ,提出了一種與觀察視點相關的動態多分辨紋理模型 ,并設計了相應的數據結構用于管理紋理數據 ,另外在討論觀察視點與紋理分辨率之間關系的基礎上 ,開發了基于視點的確定紋理分辨率的算法 ,以用于交互三維顯示時的紋理映射 ,最后給出了部分實驗結果 .實驗結果表明 ,多分辨率紋理模型的映射機制可以取得較好的可視化效果. With the development of digital earth and cyber city, there is an increasing equipment on management and vitalization of integrated 3D model data and image data. How to improve the speed and visualization effect of three-dimesional(3D) model is a major research issue in 3D GIS. In order to improve the speed of 3D visualization, such as flying/walking through, many algorithms have been developed to reduce the data volume of 3D model, for instance, Level -of -Detail(Lod) algorithm. However, image data is also another important factor effecting the operation speed and reality of 3D model. Image data as the texture of surface of 3D model can enhance the reality of 3D model. For the reason that different graphic cards may have different restriction in the size of texture, the texture has to be managed very carefully. This paper proposes a new method to manage image data when a image is used as the texture for a 3D GIS environment. First, the data structure of multi-resolution texture model, which is developed to manage the large texture, is presented. Secondly, the algorithm that creates the multi-resolution texture model is developed, which is of vital importance for the texture mapping. Thirdly, the method of determining a proper texture resolution to map texture on the surface of 3D model based on viewer conditions is discussed. Finally, several experiments are illustrated.