| VPL-based many-light rendering is a class of methods for efficient computation of global illumination, which has some problems, such as unreasonable VPL distribution, inaccurate glossy interreflection rendering, etc. We present a hybrid VPL sampling algorithm to reasonably distribute the VPL and an error-bounded algorithm to accurately render the glossy interreflection.Our VPL sampling algorithm is effective for indirect illumination rendering, especially when the camera only focus on a small part of the scene. In the progress of the generation of VPL, our method partitions the scene into two parts:the close-range part, where the camera focuses on; the distant-range part, where the camera does not focus on. For the close-range part, we present a surface-based VPL sampling method. For the distant part, we use an instant radiosity method to generate sparse VPL. Compared to traditional VPL sampling algorithms, in the case of equal VPL, our method greatly improves the quality of the final image; in the case of equal image quality, our method greatly outperforms at the rendering speed.For rendering glossy illumination, VPL-based many-light framework require a large number of lights to avoid spikes or reduce the clamping errors. In this paper, we propose an error-bounded adaptive algorithm for efficient rendering of glossy illuminations. Our approach is extended from lightcuts methods. Hierarchies are built both on lights and pixels. New error bounds, especially the one for evaluating glossy to glossy interreflections, are derived and used to conduct the traversal between light and pixel hierarchies to compute illuminations. Under such an adaptive scheme the rendering of glossy illuminations is efficiently and accurately. Results demonstrate our method is able to faithfully compute glossy interreflections, even including highly glossy and spatial varying reflectance. We implement our algorithms on GPU and achieve faster performance and better scalability than previous methods. |
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