Adaptive Multi-level Multi-phenomena Appearance Models

渲染逼真的合成场景需要精确表示3D对象和光传输。 该模拟的结果在图像中作为表面外观进行过滤，该表面外观随距离、方向、入射照明、反射特性、相互反射、次表面散射、微观几何形状和纹理而变化。光传输和可见性通常使用蒙特卡罗（MC）采样和光线跟踪的组合来解决，通过多次采样很好地适应了渲染中的大多数集成问题。 然而，它们在复杂场景中是低效的，因为它们在场景表示的最精细尺度上操作，并且因此，这种方法不针对复杂场景的实时渲染或离线高质量渲染进行缩放。相反，我们建议将几何形状、可见性和外观的预过滤表示适应像素大小，即，找到一个适当的细节层次的计算光对象的相互作用。 我们最近的LEADR方法计算整个像素足迹的颜色，交互式和独立的足迹的大小。 它是可过滤的，高效的，适用于GPU，可扩展的复杂性和高质量，但它仅限于直接照明下的纹理高度图。该研究计划将设计几种新颖的表面，体积，可见性/透明度，纹理和光传输的分层表示，以将影响外观的现象投射到我们的预过滤方法中。 我们建议将黑盒内光传输的概念推广到影响外观的所有组合因素，从而有效地确定在观看和照明条件下的适当表示，从而实现复杂场景的实时渲染，以及集成在路径跟踪方法中的适应方案。我们将从一些具体的案例研究中建立知识，如草到草坪，树到树冠，沙到沙丘，织物到窗帘，建筑到城市等，我们将开发层次结构中两个相邻级别之间的插值方案。 然后，我们将通过引入更粗层次的表示和调整插值方案来提高我们的工作方式。 接下来，我们将添加影响外观的其他效果，将它们集成到更通用的模型中。 我们的长期目标是开发一个统一的多层次多现象外观方案，适用于高质量的实时和离线渲染。

Rendering realistic synthetic scenes requires an accurate representation of 3D objects and light transport. The result of this simulation is filtered in an image as surface appearance, which varies with distance, orientation, incident illumination, reflection properties, interreflections, subsurface scattering, microgeometry, and textures. Light transport and visibility are often resolved using a combination of Monte Carlo (MC) sampling and ray tracing, well adapted through multiple sampling to most integration problems in rendering. However, they are inefficient in complex scenes because they operate on the finest-scale of the scene representation, and thus, this approach does not scale for real-time rendering of complex scenes nor offline high-quality rendering. Instead, we propose to adapt pre-filtered representations of geometries, visibility, and appearances to the pixel size, i.e., to find an appropriate level-of-detail computation for light-object interactions. Our recent LEADR method computes the color over an entire pixel footprint, interactively and independent of the footprint's size. It is filterable, efficient, suitable for GPUs, scalable with complexity, and high-quality, but it is limited to textured height maps under direct illumination.***This research program will design several novel hierarchical representations of surfaces, volumes, visibility/transparency, textures, and light transport, to cast the phenomena that affect appearance into our prefiltered approach. We propose to generalize the concept of light transport within a black box to all combined factors affecting appearance, thus efficiently determining the appropriate representation under viewing and illumination conditions, leading to real-time rendering of complex scenes, as well as an adapted scheme to be integrated in path-tracing methods.***We will build knowledge from a number of specific case studies, such as grass-to-lawn, tree-to-canopy, sand-to-dune, fabrics-to-drapes, building-to-city, etc. We will develop interpolation schemes between two adjacent levels in a hierarchy. Then we will work our way up by introducing representations at coarser hierarchy levels, and adapting interpolation schemes. Next we will add the other effects affecting appearance, integrating them into a more general model. Our long-term goal is to develop a unified multi-level multi-phenomena appearance scheme suitable for high-quality real-time and offline rendering.**