Improved explicit radiosity method for calculating non-Lambertian reflections (original) (raw)
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Proceedings of the 26th annual conference on Computer graphics and interactive techniques - SIGGRAPH '99, 1999
High quality, physically accurate rendering at interactive rates has widespread application, but is a daunting task. We attempt to bridge the gap between high-quality offline and interactive rendering by using existing environment mapping hardware in combination with a novel Image Based Rendering (IBR) algorithm. The primary contribution lies in performing IBR in reflection space. This method can be applied to ordinary environment maps, but for more physically accurate rendering, we apply reflection space IBR to radiance environment maps. A radiance environment map pre-integrates a Bidirectional Reflection Distribution Function (BRDF) with a lighting environment. Using the reflection-space IBR algorithm on radiance environment maps allows interactive rendering of arbitrary objects with a large class of complex BRDFs in arbitrary lighting environments. The ultimate simplicity of the final algorithm suggests that it will be widely and immediately valuable given the ready availability of hardware assisted environment mapping.
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ACM Transactions on Graphics, 2013
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2002
Abstract We propose texture maps that contain at each texel all the parameters of a Lafortune representation BRDF as a compact, but quite general surface appearance representation. We describe a method for rendering such surfaces rapidly on current graphics hardware and demonstrate the method with real, measured surfaces and hand-painted surfaces. We also propose a method of rendering such spatial bi-directional reflectance distribution functions using prefiltered environment maps.
Computer Graphics Forum, 2003
We present an algorithm for simulating global illumination in scenes composed of highly tessellated objects with diffuse or moderately glossy reflectance. The solution method is a higher order extension of the face cluster radiosity technique. It combines face clustering, multiresolution visibility, vector radiosity, and higher order bases with a modified progressive shooting iteration to rapidly produce visually continuous solutions with limited memory requirements. The output of the method is a vector irradiance map that partitions input models into areas where global illumination is well approximated using the selected basis. The programming capabilities of modern commodity graphics architectures are exploited to render illuminated models directly from the vector irradiance map, exploiting hardware acceleration for approximating view dependent illumination during interactive walkthroughs. Using this algorithm, visually compelling global illumination solutions for scenes of over one million input polygons can be computed in minutes and examined interactively on common graphics personal computers.
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Proceedings of the 18th …, 1991
A new progressive global illumination method is presented which produces approximate images quickly, and then continues to systematically produce more accurate images. The method combines the existing methods of progressive refinement radiosity, Monte Carlo path tracing and light ray tracing. The method does not place any limitation on surface properties such as ideal Lambertian or mirror-like.
Translucent Radiosity: Efficiently CombiningDiffuse Inter-Reflection andSubsurface Scattering
IEEE Transactions on Visualization and Computer Graphics, 2014
It is hard to efficiently model the light transport in scenes with translucent objects for interactive applications. The interreflection between objects and their environments and the subsurface scattering through the materials intertwine to produce visual effects like color bleeding, light glows, and soft shading. Monte-Carlo based approaches have demonstrated impressive results but are computationally expensive, and faster approaches model either only inter-reflection or only subsurface scattering. In this paper, we present a simple analytic model that combines diffuse inter-reflection and isotropic subsurface scattering. Our approach extends the classical work in radiosity by including a subsurface scattering matrix that operates in conjunction with the traditional form factor matrix. This subsurface scattering matrix can be constructed using analytic, measurement-based or simulation-based models and can capture both homogeneous and heterogeneous translucencies. Using a fast iterative solution to radiosity, we demonstrate scene relighting and dynamically varying object translucencies at near interactive rates.
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2000
Methods for exact computation of irradiance and form factors associated with polygonal objects have ultimately relied on a formula for a differential area to polygon form factor attributed to Lambert. This paper introduces an alternative to Lambert's formula, an analytical expression which independent of the vertex order of the polygon. In this formulation, irradiance values in a scene consisting of partially occluded uniformly emitting polygons can be computed exactly by examining only the set of apparent vertices visible from the point of evaluation, where no vertex ordering is required. The method is particularly applicable to radiosity reconstruction, in which all the scene polygons are diffuse emitters, and also in environments where efficiency structures have already been established.
Acquiring and Using Realistic Reflectance Data in Computer Graphics Images
Analytical models of light reflection are in common use in computer graphics. However, as the sophistication of rendering methods has increased, analytical models have become less adequate for generating images. Reflectance data obtained by empirically measuring real world surfaces is needed to create more realistic looking images. In this paper we examine several issues relevant to using measured reflectance functions in generating computer graphics images. We give an overview of the techniques involved in measuring and tabulating reflectance data. We compare and contrast measured reflectance functions with analytical illumination models, and evaluate several methods for interpolating tabulated reflectance functions. We also highlight potential areas of future research. 1 Introduction The most fundamental operation in rendering computer graphics images is the computation of how light reflects off surfaces. This computation is often performed using a local illumination model. This i...
Fast and accurate hierarchical radiosity using global visibility
ACM Transactions on Graphics, 1999
Recent hierarchical global illumination algorithms permit the generation of images with a high degree of realism. Nonetheless, appropriate refinement of light transfers, high quality meshing and accurate visibility calculation can be challenging tasks. This is particularly true for scenes containing multiple light sources and scenes lit mainly by indirect light. We present solutions to these problems by extending a global visibility data structure, the Visibility Skeleton. This extension allows us to calculate exact point-to-polygon form-factors at vertices created by subdivision. The structure also provides visibility information for all light interactions, allowing intelligent refinement strategies. High-quality meshing is effected based on a perceptually-based ranking strategy which results in appropriate insertions of discontinuity curves into the meshes representing illumination. We introduce a hierarchy of triangulations which allows the generation of a hierarchical radiosity solution using accurate visibility and meshing. Results of our implementation show that our new algorithm produces high quality view-independent lighting solutions for direct illumination, for scenes with multiple lights and also scenes lit mainly by indirect illumination.
Improved radiance gradient computation
Proceedings of the 21st spring conference on Computer graphics - SCCG '05, 2005
: Right: The gradient computation proposed by does not properly handle significant change of occlusion in the sampled environment and leaves visible interpolation artifacts. Left: The radiance gradient computation proposed in this paper handles occlusion changes and leads to a smoother indirect illumination interpolation on the glossy floor. The two images in the middle are cut out from the two images on the very left and very right.