Ambient Volume Scattering
Ambient Volume Scattering
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DOI：
10.1109/tvcg.2013.129
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发表时间：
2013-12
影响因子：
5.2
通讯作者：
M. Ament;F. Sadlo;D. Weiskopf
中科院分区：
文献类型：
--
作者：
M. Ament;F. Sadlo;D. Weiskopf
我们将环境散射作为直接体渲染中介观尺度散射的预积分方法。由于随着距离的增加呈指数衰减，远距离散射效应通常对给定位置的贡献可以忽略不计。这激发了我们在任何给定样本点周围的有限球形区域内预积分多重散射的方法。为此，我们在一组球形区域内通过蒙特卡罗模拟解决了完整的光传输问题，其中每个区域可能具有有关各向异性和消光的不同材料参数。该预计算独立于数据集和传递函数，并产生一个小的预积分表。在渲染期间，针对每个射线采样点相对于样本的球形邻域中的观察方向、相位函数和材料属性访问查找表。我们的渲染技术高效且通用，因为它很容易适合现有的光线行进算法，并且可以与局部照明和体积环境光遮挡相结合。它提供交互式体积散射和软阴影，并对传递函数、相位函数的各向异性参数、照明条件和视点进行交互式控制。 GPU 实现展示了环境散射对于不同类型数据集可视化在空间感知、高质量照明、半透明度和渲染速度方面的优势。
We present ambient scattering as a preintegration method for scattering on mesoscopic scales in direct volume rendering. Far-range scattering effects usually provide negligible contributions to a given location due to the exponential attenuation with increasing distance. This motivates our approach to preintegrating multiple scattering within a finite spherical region around any given sample point. To this end, we solve the full light transport with a Monte-Carlo simulation within a set of spherical regions, where each region may have different material parameters regarding anisotropy and extinction. This precomputation is independent of the data set and the transfer function, and results in a small preintegration table. During rendering, the look-up table is accessed for each ray sample point with respect to the viewing direction, phase function, and material properties in the spherical neighborhood of the sample. Our rendering technique is efficient and versatile because it readily fits in existing ray marching algorithms and can be combined with local illumination and volumetric ambient occlusion. It provides interactive volumetric scattering and soft shadows, with interactive control of the transfer function, anisotropy parameter of the phase function, lighting conditions, and viewpoint. A GPU implementation demonstrates the benefits of ambient scattering for the visualization of different types of data sets, with respect to spatial perception, high-quality illumination, translucency, and rendering speed.