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A Methodical Approach to the Evaluation of Appearance Computations
Hruška, Marcel ; Wilkie, Alexander (advisor) ; Rittig, Tobias (referee)
Various rendering techniques often use different approaches to the same aspects of the image synthesis process, mainly due to their complexity and constant development. Excluding global illumination algorithms, appearance descriptions are key distinguishing factors between the rendering systems. These descriptions might include BRDF models, support for spectral color representation, and even integration of advanced phenomena, such as fluores- cence. Unfortunately, as there are no standardized implementations of these features, their computations might not be completely accurate, which may result in their incorrect representation. This thesis describes an evaluation suite that methodically tests rendering algorithms based on their appearance reproduction capabilities. The core of the suite is a set of scenes that test five specific appearance phenomena - polarization, GGX reflectance, fluorescence, iridescence and the overall spectral accuracy. Each test case scenario contains as few scenes as possible while maximizing the number of covered aspects of the tested feature. For the user's convenience, we wrap the scenes inside an automatic workflow that runs the specified test case scenarios and displays the results. As a correctness metric, we provide manually verified reference images that are considered to...
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Fluorescence Computations in a Hero Wavelength Renderer
Mojzík, Michal ; Wilkie, Alexander (advisor) ; Kondapaneni, Ivo (referee)
Within the last decade, the offline rendering branch of computer graphics has moved towards the concept of physically-based rendering by using the path tracing algorithm. One such physically-based effect is fluorescence, where light is absorbed at one wavelength and re-emitted at another. However, to properly capture this effect, one has to utilize spectral path tracing, as opposed to colour- based path tracing. Spectral path tracing by itself suffers from colour noise, which can be reduced by utilizing the so-called Hero Wavelength Spectral Sampling (HWSS). The inclusion of wavelength shifting induced by fluorescence requires modifications to the base path tracing algorithm that HWSS wasn't designed for. This thesis provides the overview of path tracing, the current state-of-art for in- clusion of fluorescence in a rendering system, along with relevant technical details, the overview of HWSS itself as well as mathematical formulation that enables the combination of fluorescence and HWSS. Additionally, this thesis also proposes a new approach to rendering fluorescent participating media that properly handles previously overlooked failure cases. 1
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