Solomon Boulos’s research while affiliated with Stanford University and other places

The present invention extends to methods, systems, and computer program products for representing polarized light in computer models. A rendering pipeline receives three dimensional modeling data (e.g., geometric primitives) for rendering a two dimensional image are received. The modeling data includes data representing a light source The light energy from the simulated transmission of particles at each pixel of the two dimensional image is calculated for any particles transmitted in an adjoint direction from a specified view point back to the light source. The light energies from each pixel are summed to calculate the total light energy present at the specified view point. The total light energy can be forwarded to other modules in rendering pipeline to more accurately render the two dimensional image, such as, for example, representing polarized light in the two dimensional image.

We present a novel anisotropic sampling algorithm for image space shading which builds upon recent advancements in decoupled sampling for stochastic rasterization pipelines. First, we analyze the frequency content of a pixel in the presence of motion and defocus blur. We use this analysis to derive bounds for the spectrum of a surface defined over a two-dimensional and motion-aligned shading space. Second, we present a simple algorithm that uses the new frequency bounds to reduce the number of shaded quads and the size of decoupling cache respectively by 2X and 16X, while largely preserving image detail and minimizing additional aliasing.

Current GPUs perform a significant amount of redundant shading when surfaces are tessellated into small triangles. We address this inefficiency by augmenting the GPU pipeline to gather and merge rasterized fragments from adjacent triangles in a mesh. This approach has minimal impact on output image quality, is amenable to implementation in fixed-function hardware, and, when rendering pixel-sized triangles, requires only a small amount of buffering to reduce overall pipeline shading work by a factor of eight. We find that a fragment-shading pipeline with this optimization is competitive with the REYES pipeline approach of shading at micropolygon vertices and, in cases of complex occlusion, can perform up to two times less shading work.

Occlusion culling using a traditional hierarchical depth buffer, or z-pyramid, is less effective when rendering with motion blur. We present a new data structure, the tz-pyramid, that extends the traditional z-pyramid to represent scene depth values in time. This temporal information improves culling efficacy when rendering with motion blur. The tz-pyramid allows occlusion culling to adapt to the amount of scene motion, providing a balance of high efficacy with large motion and low cost in terms of depth comparisons when motion is small. Compared to a traditional z-pyramid, using the tz-pyramid for occlusion culling reduces the number of micropolygons shaded by up to 3.5x. In addition to better culling, the tz-pyramid reduces the number of depth comparisons by up to 1.4x.

We present DiagSplit, a parallel algorithm for adaptively tessellating displaced parametric surfaces into high-quality, crack-free micropolygon meshes. DiagSplit modifies the split-dice tessellation algorithm to allow splits along non-isoparametric directions in the surface's parametric domain, and uses a dicing scheme that supports unique tessellation factors for each subpatch edge. Edge tessellation factors are computed using only information local to subpatch edges. These modifications allow all subpatches generated by DiagSplit to be processed independently without introducing T-junctions or mesh cracks and without incurring the tessellation overhead of binary dicing. We demonstrate that DiagSplit produces output that is better (in terms of image quality and number of micropolygons produced) than existing parallel tessellation schemes, and as good as highly adaptive split-dice implementations that are less amenable to parallelization.

Ray tracing has long been a method of choice for off‐line rendering, but traditionally was too slow for interactive use. With faster hardware and algorithmic improvements this has recently changed, and real‐time ray tracing is finally within reach. However, real‐time capability also opens up new problems that do not exist in an off‐line environment. In particular real‐time ray tracing offers the opportunity to interactively ray trace moving/animated scene content. This presents a challenge to the data structures that have been developed for ray tracing over the past few decades. Spatial data structures crucial for fast ray tracing must be rebuilt or updated as the scene changes, and this can become a bottleneck for the speed of ray tracing. This bottleneck has recently received much attention by researchers and that has resulted in a multitude of different algorithms, data structures and strategies for handling animated scenes. The effectiveness of techniques for ray tracing dynamic scenes vary dramatically depending on details such as scene complexity, model structure, type of motion and the coherency of the rays. Consequently, there is so far no approach that is best in all cases, and determining the best technique for a particular problem can be a challenge. In this State of the Art Report (STAR), we aim to survey the different approaches to ray tracing animated scenes, discussing their strengths and weaknesses, and their relationship to other approaches. The overall goal is to help the reader choose the best approach depending on the situation, and to expose promising areas where there is potential for algorithmic improvements.

Current GPUs rasterize micropolygons (polygons approximately one pixel in size) inefficiently. We design and analyze the costs of three alternative data-parallel algorithms for rasterizing micropolygon workloads for the real-time domain. First, we demonstrate that efficient micropolygon rasterization requires parallelism across many polygons, not just within a single polygon. Second, we produce a data-parallel implementation of an existing stochastic rasterization algorithm by Pixar, which is able to produce motion blur and depth-of-field effects. Third, we provide an algorithm that leverages interleaved sampling for motion blur and camera defocus. This algorithm outperforms Pixar's algorithm when rendering objects undergoing moderate defocus or high motion and has the added benefit of predictable performance.

Designed for computer graphics, oRGB is a new color model based on opponent color theory. It works well for both HSV-style color selection and computational applications such as color transfer. oRGB also enables new applications such as a quantitative cool-to-warm metric, intuitive color manipulation and variations, and simple gamut mapping.

We introduce GRAMPS, a programming model that generalizes concepts from modern real-time graphics pipelines by exposing a model of execution containing both fixed-function and application-programmable processing stages that exchange data via queues. GRAMPS allows the number, type, and connectivity of these processing stages to be defined by software, permitting arbitrary processing pipelines or even processing graphs. Applications achieve high performance using GRAMPS by expressing advanced rendering algorithms as custom pipelines, then using the pipeline as a rendering engine. We describe the design of GRAMPS, then evaluate it by implementing three pipelines, that is, Direct3D, a ray tracer, and a hybridization of the two, and running them on emulations of two different GRAMPS implementations: a traditional GPU-like architecture and a CPU-like multicore architecture. In our tests, our GRAMPS schedulers run our pipelines with 500 to 1500KB of queue usage at their peaks.