基于图割算法的倾斜影像纹理映射优化方法

Method of Texture Mapping Optimization for Oblique Images Based on Graph Cuts Algorithm

针对基于倾斜摄影影像重建三维城市模型纹理映射过程中出现的遮挡和纹理碎片化问题,本文提出一种利用摄影光线与模型相交判断遮挡,然后利用图割算法优化纹理的方法。首先,连接摄影中心与三角形面片各顶点,判断连接线段与其他三角形面片的相交情况,从而确定是否遮挡,以选取当前三角形面片对应的未被遮挡影像。然后,根据对应关系,构建能量函数,通过图割算法最小化能量函数以确定最优纹理,使相邻三角形面片对应影像的选择趋于一致,从而解决纹理碎片化问题。通过实验证明,本文方法在大规模三维模型的纹理映射中,能够有效解决映射的遮挡重影现象,并能够极大地避免纹理碎片化问题。

To solve the problems of occlusions and texture fragmentation when mapping texture for 3D urban model generated using aerial oblique images,a method is proposed for solving the occlusion problem by using the relationship of intersection between the photography light with the model,and then the texture selection is optimized by graph cuts algorithm. Firstly,the camera position is connected to the triangle vertexes,and then occlusions are determined by judging intersection between the connecting lines and the model. After that,unshaded images corresponding to the current triangular patch are marked. After the first step,energy function is constructed according to the texture correspondence. Then graph cuts algorithm is used to minimize the energy function to determine the optimal texture for each triangle mesh,so that the corresponding image of the adjacent triangular patches tends to be the same. Thus the problem of texture fragmentation can be solved. Experiments reveal that the proposed method can effectively solve the ghosting phenomenon in the texture mapping of large-scale three-dimensional model,and can greatly alleviate the texture fragmentation problem.