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Abstract: Underwater scene is one of the most marvelous environments in the world. In this study, we present an efficient procedural modeling and rendering system to generate marine ecosystems for swim-through graphic applications. To produce realistic and natural underwater scenes, several techniques and algorithms have been presented and introduced. First, to distribute sealife naturally on a seabed, we employ an ecosystem simulation that considers the influence of the underwater environment. Second, we propose a two-level procedural modeling system to generate sealife with unique biological features. At the base level, a series of grammars are designed to roughly represent underwater sealife on a central processing unit (CPU). Then at the fine level, additional details of the sealife are created and rendered using graphic processing units (GPUs). Such a hybrid CPU-GPU framework best adopts sequential and parallel computation in modeling a marine ecosystem, and achieves a high level of performance. Third, the proposed system integrates dynamic simulations in the proposed procedural modeling process to support dynamic interactions between sealife and the underwater environment, where interactions and physical factors of the environment are formulated into parameters and control the geometric generation at the fine level. Results demonstrate that this system is capable of generating and rendering scenes with massive corals and sealife in real time.

复杂海洋生态系统的过程式生成与实时绘制

研究目的：面向具有生物多样性的大范围复杂海洋生态环境，实现对其复杂几何的高效建模生成，同时实现实时绘制。
创新要点：我们使用了一种CPU和GPU混合的过程式生成流水线，从而充分发挥了CPU的灵活性和GPU的高计算性能，取得了整体上的高效率。
研究方法：首先，考虑了海底地形、波能、光能、生物属性等影响因素，提出了一种以竞争机制为原则的生态环境模拟过程，输出区域海底环境的生物空间分布（图4）。然后，针对海洋生物个体，提出了一个两阶段的过程式生成流水线（图2）。第一阶段，在CPU上通过解码一系列语法，生成粗糙的几何外形和高度紧凑的细节信息；第二阶段，基于现代GPU的强大硬件细分能力，实时解码细节信息，完成多细节层次的生物细节几何生成。最后，针对海洋生物之间的互动，系统定制了动态模拟模块。通过对复杂物理模型的简化，在CPU上实现对海洋生物整体形状形变的实时计算。在GPU上利用该形变计算结果，生成生物的形变细节（图11）。
重要结论：针对大范围海下生态环境，提出了一种高效的过程式建模和绘制系统，达到了复杂几何的高效生成及实时三维场景漫游效果。
过程式生成；海洋生态环境；生物特性；GPU加速

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