Physically based rendering of ice crystal halos
Date
2019-02-08
Authors
Firmino, Arthur
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Abstract
The anisotropic scattering properties of atmospheric ice crystals lead to complex and
visually appealing halos, however these have yet to receive due modelling in physically
based rendering systems. This project aims to ll that gap and render high quality,
physically accurate images of these phenomena. To capture the crystal
s scattering
properties, represented by a phase function, we construct a virtual goniore
ectometer
simulating light rays incident on an ice crystal. A physically based renderer is
extended to read our phase functions, allowing halos to be rendered by a volumetric
path tracer. Multiple halos were rendered, with varying crystal shapes and orientations,
and the resulting images were qualitatively compared with real photographs.
The approaches used to approximate and sample the phase functions, despite yielding
quality images, incurr an objectionable time and space cost. Possible alternatives and
solutions are discussed in conclusion.
Description
Keywords
rendering, physically based rendering, halos, anisotropic scattering, computer graphics