中文摘要：

光子图是一种高效的全局光照算法,能够模拟物理真实感光照效果。然而,经典的光子图算法的光辐射强度估算不够准确,尤其在物体的细节区域光通量计算有很大误差,细节部分的绘制质量很差。分析了光辐射强度估计的过程,找到了产生较大误差的原因,进而提出了一种改进的光辐射强度估算方法。对于搜索范围内的每个光子,求出它在绘制点的切平面上的投影,判断投影点与绘制点之间的距离是否小于搜索半径,进而决定是否使用该光子计算光通量。改进后的算法虽然增加了一些计算时间,但是显著地提高了光辐射强度估计的准确性。理论分析和场景测试证明改进后的算法明显改善了物体细节部分的绘制效果。

英文摘要：

Photon mapping is an efficient global illumination algorithm, capable of simulating physically based illumination effects. However, radiance estimation of classic photon mapping is not accurate enough, especially for surface details, resulting in poor rendering quality in detail areas. An improved radiance estimation method was proposed. For each photon within the search scope, the projection on the tangent plane of the rendering point was calculated, and then the distance between the projection and the rendering point was compared with the search radius to decide whether the photon should be used for the radiance estimation. The radiance estimation is greatly improved at a little additional time cost. Theoretical analysis and experimental results show that the algorithm greatly improves the rendering quality of surface details.