一种基于非平滑特征的简化实景网格评价方法

不同于一般简化网格评价,简化倾斜摄影三维重建生成的城市数字表面模型UDSM(urban digital surfacemodel)网格应更加注重基础设施结构的保持。现有的简化三角网量化评价方法主要包括与原网格的差异、平滑度、三角网的几何质量,不适用于非平滑的UDSM。尽管网格简化研究中,基本都强调其简化结果与原网格特征保持效果,但误差量化标准常常和优良的简化效果不匹配。针对UDSM非平滑的特征,以及倾斜摄影建模的误差,将提取城区模型的平整表面并与细节网格分别进行误差分析,以弥补Metro工具误差测量的不足。这些评价也客观定量地证明了网格简化除了产生误差,也会改善其质量。

SIMPLIFIED SURFACE MESH EVALUATION BASED ON UNFLATNESS FEATURE

Different from mesh simplification in general cases,more attention should be placed on keeping the infrastructural structure when simplifying meshes of urban digital surface model(UDSM)generated by 3D reconstruction through oblique photogrammetry.Present evaluation towards simplified TINs mainly includes error compared to original surfaces,smoothness and geometrical quality of TINs themselves,which is unsuitable for UDSM.Although some researches on simplifying surface meshes lay emphasis on maintaining traits compared to original surfaces,their results of error compared to original surfaces are not consistent with their nice results.To cope with unflatness of UDSMs and reconstruction errors caused by oblique photography,planar surfaces were extracted from urban models and analyses were given to planar and detail ones respectively,to improve the deficiency of numeric error measuring tool Metro.Such evaluation proves that mesh simplification can improve its quality besides bringing about error in a numeric and objective manner.