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【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。
【Objective】 In order to truly simulate the real-time dynamic effects of sun and shadow in forest scenes, a visual simulation of natural resources and optimization of computing resources is combined to realize real-time dynamic rendering of large-scale forest scene shadow. 【Method】 The sun and shadow scenes were constructed by using the sub-node rotation method, the sun scene was drawn by Billboard technique, and the shadow was drawn by PSSM algorithm. Establish their own child nodes and bind them to a common root node, and realize the real-time changes of the tree shadow form with the sun’s rising and falling by rotating the child nodes in the world coordinate system at the same time, and compare the rendering efficiency when there is shading . 【Result】 The results showed that the shading efficiency was as high as 70.0 frames / s when the number of trees was more than 5 000 trees. When the number of shading trees was more than 6 000 trees, the shading efficiency showed a relatively gentle decreasing trend, and the shading was the average rendering efficiency Of the 70%; when loading 19 000 trees, the shading efficiency is 16.0 frames / s. 【Conclusion】 The experimental data of sub-node rotation method is easy to obtain, the algorithm is simple and fast, and the efficiency is high. The drawing effect makes the forest scene more realistic, which can achieve better visual effects and meet the requirements of real-time visualization.