Realistic Rendering of Water Surfaces
Realistické zobrazování vodních ploch
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České vysoké učení technické v Praze
Czech Technical University in Prague
Czech Technical University in Prague
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Abstract
Tato práce se zaměřuje na realistické zobrazování hladiny převážně stojatých vodních ploch, tj. jezer a oceánů bez velkých vln. Možná využití jsou převážně ve filmovém průmyslu, jelikož simulátory a počítačové hry obvykle musejí obětovat realismus aby dosáhly dostatečné snímkovací frekvence. Vzhled vodních ploch se liší poměrně značně, a to nejen kvůli tvaru hladiny, ale i čistotě vody a dopadajícím světlem. Scéna je nasvícena analytickým modelem slunce a světla od oblohy. Tvar vodní hladiny je získán z frekvenčního spektra mořských vln pomocí inverzní Fourierovy transformace. Odrazové vlastnosti hladiny jsou modelovány pomocí mikroploškové BSDF, kde distribuce plošek je založena na statistické distribuci plošek mořské hladiny. Bio-optický model vody je parametrizován koncentrací planktonu, organických a anorganických nečistot. Voda je zobrazena pomocí aproximace difůzním rozptylem, konkrétně metodou isotropního dipólu (v kombinaci s jednonásobným rozptylem) a směrového dipólu. Rychlost konvergense obou metod je porovnána s volumetrickým sledováním cest.
This thesis focuses on rendering realistic images of mostly still water bodies, such as lakes or oceans with only small waves on the surface. Possible uses are especially in the movie industry, as simulators or computer games often need to sacrifice realism to achieve interactive framerates. The appearance of water bodies differs quite substantially based on not only the shape of the surface but also on the water constituents and the color of incident light. An analytical model of sun and sky radiance is used to light the scene. The shape of the surface is obtained from a sea wave spectrum using the inverse Fourier transform. Reflective properties of the surface are modeled by a microfacet BSDF, where the microfacet slope distribution is based on statistical sea slope distribution. The bio-optical model of the water is parametrized by the concentration of phytoplankton, common dissolved organic material (CDOM), and inorganic particulate matter. The scenes are rendered using diffusion approximations, specifically isotropic dipole (in combination with single scattering) and directional dipole. The convergence rate of both methods is compared with volumetric path tracing.
This thesis focuses on rendering realistic images of mostly still water bodies, such as lakes or oceans with only small waves on the surface. Possible uses are especially in the movie industry, as simulators or computer games often need to sacrifice realism to achieve interactive framerates. The appearance of water bodies differs quite substantially based on not only the shape of the surface but also on the water constituents and the color of incident light. An analytical model of sun and sky radiance is used to light the scene. The shape of the surface is obtained from a sea wave spectrum using the inverse Fourier transform. Reflective properties of the surface are modeled by a microfacet BSDF, where the microfacet slope distribution is based on statistical sea slope distribution. The bio-optical model of the water is parametrized by the concentration of phytoplankton, common dissolved organic material (CDOM), and inorganic particulate matter. The scenes are rendered using diffusion approximations, specifically isotropic dipole (in combination with single scattering) and directional dipole. The convergence rate of both methods is compared with volumetric path tracing.