303 research outputs found
Towards interactive global illumination effects via sequential Monte Carlo adaptation
Journal ArticleThis paper presents a novel method that effectively combines both control variates and importance sampling in a sequential Monte Carlo context while handling general single-bounce global illumination effects. The radiance estimates computed during the rendering process are cached in an adaptive per-pixel structure that defines dynamic predicate functions for both variance reduction techniques and guarantees well-behaved PDFs, yielding continually increasing efficiencies thanks to a marginal computational overhead
Second-Order Occlusion-Aware Volumetric Radiance Caching
We present a second-order gradient analysis of light transport in
participating media and use this to develop an improved radiance caching
algorithm for volumetric light transport. We adaptively sample and interpolate
radiance from sparse points in the medium using a second-order Hessian-based
error metric to determine when interpolation is appropriate. We derive our
metric from each point's incoming light field, computed by using a proxy
triangulation-based representation of the radiance reflected by the surrounding
medium and geometry. We use this representation to efficiently compute the
first- and second-order derivatives of the radiance at the cache points while
accounting for occlusion changes.
We also propose a self-contained two-dimensional model for light transport in
media and use it to validate and analyze our approach, demonstrating that our
method outperforms previous radiance caching algorithms both in terms of
accurate derivative estimates and final radiance extrapolation. We generalize
these findings to practical three-dimensional scenarios, where we show improved
results while reducing computation time by up to 30\% compared to previous
work
GI-1.0: A Fast and Scalable Two-level Radiance Caching Scheme for Real-time Global Illumination
Real-time global illumination is key to enabling more dynamic and physically
realistic worlds in performance-critical applications such as games or any
other applications with real-time constraints.Hardware-accelerated ray tracing
in modern GPUs allows arbitrary intersection queries against the geometry,
making it possible to evaluate indirect lighting entirely at runtime. However,
only a small number of rays can be traced at each pixel to maintain high
framerates at ever-increasing image resolutions. Existing solutions, such as
probe-based techniques, approximate the irradiance signal at the cost of a few
rays per frame but suffer from a lack of details and slow response times to
changes in lighting. On the other hand, reservoir-based resampling techniques
capture much more details but typically suffer from poorer performance and
increased amounts of noise, making them impractical for the current generation
of hardware and gaming consoles. To find a balance that achieves high lighting
fidelity while maintaining a low runtime cost, we propose a solution that
dynamically estimates global illumination without needing any content
preprocessing, thus enabling easy integration into existing real-time rendering
pipelines
Photon Mapping
V rámci tĂ©to práce byla provedena praktická implementace algoritmu photon mapping. Pro dosaĹľenĂ kvalitnÄ›jšĂho vĂ˝stupu byly zkoumány nÄ›kterĂ© základnĂ a pokroÄŤilejšà metody globálnĂho osvÄ›tlenĂ. Tyto nároÄŤnĂ© algoritmy jsou ÄŤasto prakticky nepouĹľitelnĂ© a je nutná jejich optimalizace. Základem praktickĂ© implementace je optimalizace raytraceru. Vzorky nepĹ™ĂmĂ©ho difuznĂho osvÄ›tlenĂ poÄŤĂtanĂ© metodou Monte Carlo je moĹľnĂ© mezi sebou interpolovat s pouĹľitĂm vhodnĂ© techniky.This thesis deals with practical implementation of photon mapping algorithm. To achieve better results some basic and some more advanced methods of global illumination has been examined. These time demanding algorithms are often practically unusable and their further optimization is necessary. Optimized ray tracer is essential for practical implementation. Computing diffuse interreflection by Monte Carlo sampling is also very time demanding operation. Therefore it is appropriate to use it along with proper interpolation.
Interactive global illumination on the CPU
Computing realistic physically-based global illumination in real-time remains one
of the major goals in the fields of rendering and visualisation; one that has not
yet been achieved due to its inherent computational complexity. This thesis focuses
on CPU-based interactive global illumination approaches with an aim to
develop generalisable hardware-agnostic algorithms. Interactive ray tracing is reliant
on spatial and cache coherency to achieve interactive rates which conflicts
with needs of global illumination solutions which require a large number of incoherent
secondary rays to be computed. Methods that reduce the total number of
rays that need to be processed, such as Selective rendering, were investigated to
determine how best they can be utilised.
The impact that selective rendering has on interactive ray tracing was analysed
and quantified and two novel global illumination algorithms were developed,
with the structured methodology used presented as a framework. Adaptive Inter-
leaved Sampling, is a generalisable approach that combines interleaved sampling
with an adaptive approach, which uses efficient component-specific adaptive guidance
methods to drive the computation. Results of up to 11 frames per second
were demonstrated for multiple components including participating media. Temporal Instant Caching, is a caching scheme for accelerating the computation of
diffuse interreflections to interactive rates. This approach achieved frame rates
exceeding 9 frames per second for the majority of scenes. Validation of the results
for both approaches showed little perceptual difference when comparing
against a gold-standard path-traced image. Further research into caching led to
the development of a new wait-free data access control mechanism for sharing the
irradiance cache among multiple rendering threads on a shared memory parallel
system. By not serialising accesses to the shared data structure the irradiance
values were shared among all the threads without any overhead or contention,
when reading and writing simultaneously. This new approach achieved efficiencies
between 77% and 92% for 8 threads when calculating static images and animations.
This work demonstrates that, due to the
flexibility of the CPU, CPU-based
algorithms remain a valid and competitive choice for achieving global illumination
interactively, and an alternative to the generally brute-force GPU-centric
algorithms
Photorealistic physically based render engines: a comparative study
PĂ©rez Roig, F. (2012). Photorealistic physically based render engines: a comparative study. http://hdl.handle.net/10251/14797.Archivo delegad
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