Article records
https://feeds.library.caltech.edu/people/Arvo-J-R/article.rss
A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenFri, 12 Apr 2024 23:15:12 +0000Particle transport and image synthesis
https://resolver.caltech.edu/CaltechAUTHORS:20160420-134938858
Authors: {'items': [{'id': 'Arvo-J-R', 'name': {'family': 'Arvo', 'given': 'James'}}, {'id': 'Kirk-David', 'name': {'family': 'Kirk', 'given': 'David'}}]}
Year: 1990
DOI: 10.1145/97880.97886
The rendering equation is similar to the linear Boltzmann
equation which has been widely studied in physics and nuclear engineering. Consequently, many of the powerful techniques which have been developed in these fields can be
applied to problems in image synthesis. In this paper we
adapt several statistical techniques commonly used in neutron transport to stochastic ray tracing and, more generally, to Monte Carlo solution of the rendering equation. First, we describe a technique known as Russian roulette which can be used to terminate the recursive tracing of rays without introducing statistical bias. We also examine the practice of creating ray trees in classical ray tracing in the light of a
well-known technique in particle transport known as splitting. We show that neither ray trees nor paths as described in [10] constitute an optimal sampling plan in themselves and that a hybrid may be more efficient.https://authors.library.caltech.edu/records/jd7a5-67124Unbiased sampling techniques for image synthesis
https://resolver.caltech.edu/CaltechAUTHORS:20161116-153206206
Authors: {'items': [{'id': 'Kirk-David', 'name': {'family': 'Kirk', 'given': 'David'}}, {'id': 'Arvo-J-R', 'name': {'family': 'Arvo', 'given': 'James'}}]}
Year: 1991
DOI: 10.1145/127719.122735
We examine a class of adaptive sampling techniques employed in image synthesis and show that those commonly used for efficient anti-aliasing are statistically biased. This bias is dependent upon the image function being sampled as well as the strategy for determining the number of samples to use. It is most prominent in areas of high contrast and is attributable to early stages of sampling systematically favoring one extreme or the other. If the expected outcome of the entire adaptive sampling algorithm is considered, we find that the bias of the early decisions is still present in the final estimator. We propose an alternative strategy for performing adaptive sampling that is unbiased but potentially more costly. We conclude that it may not always be practical to mitigate this source of bias, but as a source of error it should be considered when high accuracy and image fidelity are a central concern.https://authors.library.caltech.edu/records/8sntk-73q87Perturbation methods for interactive specular reflections
https://resolver.caltech.edu/CaltechAUTHORS:20170408-171427414
Authors: {'items': [{'id': 'Chen-Min', 'name': {'family': 'Chen', 'given': 'Min'}}, {'id': 'Arvo-J-R', 'name': {'family': 'Arvo', 'given': 'James'}}]}
Year: 2000
DOI: 10.1109/2945.879786
We describe an approach for interactively approximating specular reflections in arbitrary curved surfaces. The technique is applicable to any smooth implicitly defined reflecting surface that is equipped with a ray intersection procedure; it is also extremely efficient as it employs local perturbations to interpolate point samples analytically. After ray tracing a sparse set of reflection paths with respect to a given vantage point and static reflecting surfaces, the algorithm rapidly approximates reflections of arbitrary points in 3-space by expressing them as perturbations of nearby points with known reflections. The reflection of each new point is approximated to second-order accuracy by applying a closed-form perturbation formula to one or more nearby reflection paths. This formula is derived from the Taylor expansion of a reflection path and is based on first and second-order path derivatives. After preprocessing, the approach is fast enough to compute reflections of tessellated diffuse objects in arbitrary curved surfaces at interactive rates using standard graphics hardware. The resulting images are nearly indistinguishable from ray traced images that take several orders of magnitude longer to generate.https://authors.library.caltech.edu/records/p4qew-app65Theory and Application of Specular Path Perturbation
https://resolver.caltech.edu/CaltechAUTHORS:20160822-152504191
Authors: {'items': [{'id': 'Chen-Min', 'name': {'family': 'Chen', 'given': 'Min'}}, {'id': 'Arvo-J-R', 'name': {'family': 'Arvo', 'given': 'James'}}]}
Year: 2000
DOI: 10.1145/380666.380670
In this paper we apply perturbation methods to the problem of computing specular reflections in curved surfaces. The key idea is to generate families of closely related optical paths by expanding a given path into a high-dimensional Taylor series. Our path perturbation method is based on closed-form expressions for linear and higher-order approximations of ray paths, which are derived using Fermat's Variation Principle and the Implicit Function Theorem (IFT). The perturbation formula presented here holds for general multiple-bounce reflection
paths and provides a mathematical foundation for exploiting path coherence in ray tracing acceleration techniques and incremental rendering. To illustrate its use, we describe an
algorithm for fast approximation of specular reflections on curved surfaces; the resulting images are highly accurate and nearly indistinguishable from ray traced images.https://authors.library.caltech.edu/records/yet8v-akc20