Abstract: In the course real-time rendering of large scale terrain,if the ground feature model and the terrain model cannot match with each other,cannot feel the verisimilitude of the virtual terrain environment.This paper gives a seamless matching method of the ground feature model based on cross patch and block based error metric ROAM algorithm.Firstly,the conception of spatial raster index is also applied.Then,a new data structure is proposed,and the intersection point set of ground feature’s boundary with terrain triangulation is efficiently sought.Finally,the polygon in the range of the ground feature is calculated based on this intersection point set.Experimental results show that the algorithm proposed can seamlessly match ground feature model with terrain model,and the rendering speed can satisfy the real-time display’s need.

摘要： 在大规模地形实时可视化中,地物模型能否与地形模型无缝叠加将直接关系到视觉感受的逼真程度。在跨图幅分块度量ROAM算法的基础上提出了地物模型无缝叠加的算法,并引入网格索引概念,提出一种新的数据结构以快速的求取地物边界与地形三角网的交点集,根据该交点集算出属于地物范围内的多边形。实验结果表明,该算法能很好地解决地物模型与地形表面的无缝叠加问题,而且绘制速度能达到实时显示的要求。