Moritz Meier
Simulating Windows for Lighting Design Optimization

Information

Abstract

For lighting design, optimizing windows plays a major role, especially for office and living spaces, as natural light is important for focus, productivity and also mood. The rendering framework Tamashii, which is currently in development at the research unit of computer graphics at TU Wien, offers a feature to automatically optimize multiple parameters of light sources like the position, intensity or rotation for a predefined lighting target. This thesis aims to expand the possibilities Tamashii offers for lighting design by simulating windows through area lights. Tamashii’s automatic light parameter optimization relies on light tracing, which unlike path tracing, casts the light rays from the light sources instead of the camera. This is why implementing environment maps in a classical sense is not feasible, as emitting light rays from each pixel of the environment map only for a small percentage to go through the window is very inefficient. We implement a new type of light that combines area lights with Illuminating Engineering Society (IES) lights in order to simulate windows. The IES standard is a file format commonly used by luminaire manufacturers to describe the physical properties of a luminaire for simulation in software. To accurately mimic the light that shines through real windows, we convert High Dynamic Range (HDR) files into IES profiles, which our lights can then use. Our new light type can also be attached to models in the scene, such as walls or roofs, which constrains the manual movement of the windows to the connected object and makes their usage more intuitive. In our tests, we find that our implementation is able to realistically simulate real windows when compared to the same combination of scenes and HDR files in Blender’s path tracing renderer Cycles. To ensure that the light parameter optimization algorithm only moves the window lights inside the model its connected to, we implement a constraint that gets evaluated repeatedly while optimizing. We realize this by calculating penalties when the light reaches the edges of the model, in order to encourage the algorithm to keep the window light inside. When evaluating our implementation we find that with the activated constraint, the algorithm is able to find valid positions for the window lights when optimizing.

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BibTeX

@bachelorsthesis{Meier_2024_WIALT,
  title =      "Simulating Windows for Lighting Design Optimization",
  author =     "Moritz Meier",
  year =       "2024",
  abstract =   "For lighting design, optimizing windows plays a major role,
               especially for office and living spaces, as natural light is
               important for focus, productivity and also mood. The
               rendering framework Tamashii, which is currently in
               development at the research unit of computer graphics at TU
               Wien, offers a feature to automatically optimize multiple
               parameters of light sources like the position, intensity or
               rotation for a predefined lighting target. This thesis aims
               to expand the possibilities Tamashii offers for lighting
               design by simulating windows through area lights.
               Tamashii’s automatic light parameter optimization relies
               on light tracing, which unlike path tracing, casts the light
               rays from the light sources instead of the camera. This is
               why implementing environment maps in a classical sense is
               not feasible, as emitting light rays from each pixel of the
               environment map only for a small percentage to go through
               the window is very inefficient. We implement a new type of
               light that combines area lights with Illuminating
               Engineering Society (IES) lights in order to simulate
               windows. The IES standard is a file format commonly used by
               luminaire manufacturers to describe the physical properties
               of a luminaire for simulation in software. To accurately
               mimic the light that shines through real windows, we convert
               High Dynamic Range (HDR) files into IES profiles, which our
               lights can then use. Our new light type can also be attached
               to models in the scene, such as walls or roofs, which
               constrains the manual movement of the windows to the
               connected object and makes their usage more intuitive. In
               our tests, we find that our implementation is able to
               realistically simulate real windows when compared to the
               same combination of scenes and HDR files in Blender’s path
               tracing renderer Cycles. To ensure that the light parameter
               optimization algorithm only moves the window lights inside
               the model its connected to, we implement a constraint that
               gets evaluated repeatedly while optimizing. We realize this
               by calculating penalties when the light reaches the edges of
               the model, in order to encourage the algorithm to keep the
               window light inside. When evaluating our implementation we
               find that with the activated constraint, the algorithm is
               able to find valid positions for the window lights when
               optimizing.",
  month =      dec,
  address =    "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria",
  school =     "Research Unit of Computer Graphics, Institute of Visual
               Computing and Human-Centered Technology, Faculty of
               Informatics, TU Wien ",
  URL =        "https://www.cg.tuwien.ac.at/research/publications/2024/Meier_2024_WIALT/",
}