关键词: 大尺度场景, 雪模拟, 细节层次, 粒子系统

Abstract: In large-scale 3D complex scenes，a real-time simulation method is presented for multi-level snowfall and snow cover.Aiming at the continuity，consistency and multi-level characters of large-scale weather scene，the view-dependent linear packet transform method is used to update snow particle systems，and visual effects of snowfall are improved.For the characteristics of large-scale and complex spatial features in landscapes，a view-dependent occlusion map is created to render details of snow cover on near features in the view frustum，while the grayscale texture as a snow map is generated to approximate snow cover simulation of the distant features，to achieve real-time multi-level simulation of snow cover in a large-scale scene.During the snow rendering process，parameters of the view frustum and occlusion map for snow details are acquired on CPU.The complex location of snow cover and the calculation of the amount of snow cover are moved from CPU to GPU，using the customized GPU vertex and fragment operations to speed up the snow simulation.Experiments show that，the method proposed in this paper can achieve a good multi-level snow simulation in large-scale 3D complex landscapes.

Key words: large-scale scene, snow simulation, level of detail, particle systems