Physically based rendering of mist and fog using MCML
Zhi Kang Shao
Department of Information and Computing Sciences, Utrecht University
This is the result of an experimentation project, done over the course of approximately 3 months (September 2013 - November 2013), performed by Master students Mattijs Driel and Zhi Kang Shao, under the supervision of dr. Robby T. Tan at Utrecht University. The project has been performed in a semi-collaborative fashion, with both Mattijs Driel and Zhi Kang Shao having produced the same implementation, but with differing focus in the experiments. This page shows the results of the experiments performed by Zhi Kang Shao.
Current techniques for rendering participating media either don't take into account multiple scattering or don't handle scenes with multiple adjacent volumes properly. MCML is a light transport model that supports both, but can only be used in setups with parallel layers. In this work we study MCML's usability for rendering scenes with with arbitrary geometry of urban scale, whereas previously it has only been used for multi-layered tissue. We hypothesize that MCML can be used for rendering homogeneous mist, that it can be extended to support inhomogeneous volumes, and specifically, it can be used for physically based rendering of clouds. We extended MCML to be able to do this. Our experiments compare renders of mist, smoke and clouds to photographs and renders with single scattering. Our results indicate that MCML performs quite well as a light transport model for general scenes with participating media.
Physically Based Rendering of Mist and Fog using MCML
Results: Rendering mist
Several mist renders with MCML and a reference photo (top right).
Results: Rendering fog clouds
Two fog renders with MCML (left) and two reference photographs (right).
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