森林场景中太阳与阴影实时动态可视化模拟

【目的】为真实地模拟森林场景中太阳与阴影的实时动态效果,将优化计算资源与自然光照的可视化模拟相结合,实现大规模森林场景阴影实时动态绘制。【方法】用子节点旋转方法分别构建太阳和阴影场景,采用Billboard技术进行太阳场景绘制,使用PSSM算法绘制阴影。建立各自子节点并绑定于共同的根节点上,通过在世界坐标系统中同时旋转子节点实现树木阴影形态随太阳一日升降的实时变化过程,并对有无阴影时的渲染效率进行了比较。【结果】加载5 000棵树以内,阴影绘制效率高达70.0 帧/s; 加载超过6 000棵树时,有无阴影的绘制效率都呈相对平缓下降趋势,且有阴影是无阴影时平均绘制效率的70%; 加载19 000棵树时,阴影绘制效率为16.0帧/s。【结论】子节点旋转方法试验数据容易获取,算法简单快速,效率较高,绘制效果使森林场景更加逼真,可以达到较好的视觉效果并满足实时可视化要求。

Real-time dynamic visual simulation of sunlight and shadows in forest scenes

[Objective]3D forest visualization simulation is an active area of current forest research. In order to combine resource optimization with natural light when simulating shadow real-time dynamics in large-scale forest scenes, a novel rotation method based on child nodes was proposed.[Method]The sun and shadow child nodes, and a blind on the com-mon root node were established by Billboard and PSSM, and then rotate the child nodes within the world coordinate sys-tem simultaneously to implement real-time dynamic process simulation of tree shadow shapes during the daytime. In addi-tion, rendering efficiency was compared.[Result]The results showed that shadow rendering efficiency reached 70. 0 frames/s when loading up to 5000 trees;when loading more than 6000 trees, rendering efficiency declined gently,both with and without the presence of shadows, and average rendering efficiency in forest scenes with shadow was almost 0.7 times than that of scenes without shadow. Additionally, shadow rendering efficiency was 16. 0 frames/s in real-time dy-namic forest scenes composed of approximately 19000 trees.[Conclusion] The experimental data for this approach can be easily obtained, and the simple, fast,and efficient algorithmcan render more realistic forest scenes, meet the require-ments of real-time visualization,and produce better visual effects.