Figure 1: Image-space photon mapping can compute global illumination at interactive rates for scenes with multiple lights, caustics, shadows, and complex BSDFs. This scene renders at 26 Hz at 1920×1080. (Indirect and ambient intensity are amplified for comparison in this image.) We describe an extension to photon mapping that recasts the most expensive steps of the algorithm – the initial and final photon bounces – as image-space operations amenable to GPU acceleration. This enables global illumination for real-time applications as well as accelerating it for offline rendering. Image Space Photon Mapping (ISPM) rasterizes a light-space bounce map of emitted photons surviving initial-bounce Russian roulette sampling on a GPU. It then traces photons conventionally on the CPU. Traditional photon mapping estimates final radiance by gathering photons from a k-d tree. ISPM instead scatters indirect illumination by rasterizing an array of photon volumes. Each volume bounds a filter kernel based on the a priori probability density of each photon path. These two steps exploit the fact that initial path segments from point lights and final ones into a pinhole camera each have a common center of projection. An optional step uses joint bilateral upsampling of irradiance to reduce the fill requirements of rasterizing photon volumes. ISPM preserves the accurate and physically-based nature of photon mapping, supports arbitrary BSDFs, and captures both high- and low-frequency illumination effects such as caustics and diffuse color interreflection. An implementation on a consumer GPU and 8-core CPU renders highquality global illumination at up to 26 Hz at HD (1920×1080) resolution, for complex scenes containing moving objects and lights.

In this paper we present two new algorithms to progressively preview an image accounting for global illumination effects while it is being rendered. These algorithms are based on a partition of the image plane using a conductance map, able to represent strong boundaries---the properties vary significantly on either side of each boundary. The eye radiances are then computed at well chosen points of the resulting triangulation, using some homogeneity measure to steer the adaptive sampling scheme. The proposed algorithms are efficient and easy to implement.

Realistic image synthesis is the process of generating images that give a human observer the same visual impression that would be experienced in viewing the real scene. This process involves different areas, like physics (light, material’s optical properties), human perception, mathematics (integral equations) and algorithms. In order to generate realistic images, global illumination models are required. These models account for the inter-reflection of light between the elements of the scene. Kajiya showed in 1986 that they are derived from the rendering equation [74]. Having its origins in the Radiative Transfer field [146], Kajiya reformulated the equation to model the (optical) physical phenomena of interest from the point of view of image synthesis. Thus, it does not consider for instance the phase of the light (diffraction is not studied, and the scattering is assumed to be incoherent, i.e. phase differences between scattered waves are not taken into account [23]), and fluorescence and phosphorescence are deemed unimportant. The rendering equation in its primitive form considers scenes made up exclusively of surfaces. In this scenario light travels along straight lines ignoring absorption or scattering by the medium, interacting only at surfaces, and the governing equation is an integral equation. When this assumption of vacuum or clear air between objects is not valid, then light interacts not only at surface

Ray tracing exhibits visible temporal aliasing artifacts in interactive viewing of complex datasets. We present a technique to reduce scintillation in point sampled imagery by targeting new rays to intersection points from previous frames.

Abstract With the development of real-time ray tracing in recent years, it is now very interesting to ask if real-time performance can be achieved for high-quality rendering algorithms based on ray tracing. In this paper, we propose a pipelined architecture to implement reverse photon mapping. Our architecture can use realtime ray tracing to generate photon points and camera points, so the main challenge is how to implement the gathering phase that computes the final image. Traditionally, the gathering phase of photon mapping has only allowed coarse-grain parallelism, and this situation has been a source of inefficiency, cache thrashing, and limited throughput. To avail fine-grain pipelining and data parallelism, we arrange computations so that photons can be processed independently, similar to the way that triangles are efficiently processed in traditional realtime graphics hardware. We employ several techniques to improve cache behavior and to reduce communication overhead. Simulations show that the bandwidth requirements of this architecture are within the capacity of current and future hardware, and this suggests that photon mapping may be a good choice for real-time performance in the future. 1

This dissertation focuses on the many issues that arise from the visual rendering problem. Of primary consideration is light transport simulation, which is known to be computationally expensive. Monte Carlo methods represent a simple and general class of algorithms often used for light transport computation. Unfortunately, the images resulting from Monte Carlo approaches generally suffer from visually unacceptable noise artifacts. The result of any light transport simulation is, by its very nature, an image of high dynamic range (HDR). This leads to the issues of the display of such images on conventional low dynamic range devices and the development of data compression algorithms to store and recover the corresponding large amounts of detail found in HDR images. This dissertation presents our contributions relevant to these issues. Our contributions to high dynamic range image processing include tone mapping and data compression algorithms. This research proposes and shows the efficacy of a novel level set based tone mapping method that preserves visual details in the display of high dynamic range images on low dynamic range display devices. The level set method is used to extract the high

The 3DCGiRAM is a 3D-graphic accelerator designed for photo-realistic image synthesis. The 3DCGiRAM is equipped with graphics processing units that perform ray-object intersection calculations and intensity calculations for rays traced over a 3D virtual object space. It also has a hardwareaccelerated 3D line generator, which e#ectively finds objects in a grid space that are likely to intersect traced rays. In this paper, we present the architecture of the 3DCGiRAM for interactive ray tracing and discuss its performance based on the experimental results obtained through rendering a raytraced walk-through animation. The experimental results show that the 3DCGiRAM with small on-chip caches running at 333MHz will be able to have a potential to synthesize a ray-traced walk-through animation at a rate of 10 frames per second.