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Advanced Rendering Toolkit
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One feature of ART is the ability to perform its illumination computations using polarizable light, instead of the more usual plain colour representations. To our knowledge ART is currently the only general-purpose rendering system in existence that is capable of taking this phenomenon into account.
Since the light and filter operations get more complex (and hence slower) in the polarizing case, this is a compile-time option for all colour types. The performance loss for the polarizing renderer is roughly in the range of 50 to 200 percent, depending on the scene. A detailed analysis of this will be made available in a technical report.
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A simple scene that shows three metal spheres (copper, gold and silver) as well as several distant metal spheres reflected in a glass wall. The wall is viewed at a rather shallow angle in order to increase the reflectivity of the glass, and for better comparability with the images with polarizing filters a 50 percent neutral grey filter has been placed in front of the observer in the same place as the polarizing filter there. This image was computed using a version of the rendering software that is not capable of taking polarization into account. |
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This is exactly the same scene as the first, only that it was rendered by a polarizing raytracer. The differences to the nonpolarizing version are very subtle - the only differences (and they are hardly noticeable) are to be seen at grazing angles of the reflected spheres in the glass wall. |
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The above scene viewed through a horizontal polarizing filter. Observe how dark the reflection on the wall is in comparison to the unpolarized scene above, and note the patterns on the reflected metal spheres, as well as the the colour shifts on the directly viewed copper and gold spheres. The reflection is not completely canceled out because the wall is being viewed well below Brewster's angle, where polarization of reflected light would be total. |
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Same as above, only viewed through a vertical polarizer. The main reflection gets much brighter by comparison, and the patterns on the metal spheres are reversed against the horizontal polarizing case. |