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Advanced Rendering Toolkit
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ART is now capable of taking crosstalk between light wavelengths into account when calculating images, an effect commonly known as fluorescence. As with polarization, ART is to our knowledge currently the only general-purpose rendering system in existence that is capable of directly rendering this phenomenon (instead of e.g. faking it with shaders). Moreover, as far as we know it is the first system ever which is capable of performing calculations which use both fluorescence and polarization information simultaneously. If you happen to know of another system that is also capable of this, do tell us. We are curious if this has been done before, since the computer graphics literature apparently does not contain any references.
Example renderings of polarization effects combined with fluorescent objects. |
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The left and right columns show similar setups under two different illuminations - at the left D65, and at the right UV blacklight. The scene shows several metal spheres (gold, copper, silver) and a nonfluorescent object (the biplane model) which float over a diffuse floor with fluorescent properties, and which are reflected in a large block of a dieelectric material (glass). The reflection is viewed well below Brewster's angle in order to increase its intensity; because of this, the polarizing filters which are placed in front of the camera in the two lower images do not affect the entire reflected energy. The horizontal polarizer in the middle cancels out a considerable part of the reflection, while the vertical one at the bottom makes the reflection brighter. Also worth noticing are the colour shifts in the copper sphere in these two cases. For comparison purposes, the topmost two images have a 50 percent neutral grey filter instead of a polarizer placed in front of the camera. Note: these images are only rendered with 1 sample per pixel because the introduction of fluorescence information appartently triggered a dormant bug in the adaptive raytracer that only manifests itself in conjunction with specular surfaces. This will be fixed in due course. |
Sample radiosity scene with fluorescent pigments. |
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A typical radiosity box, lit by D65 and UV blacklight. The objects and the walls are partly coloured with empirically modelled fluorescent pigments that are similar to those in the previous example. It has to be noted that these pigments were tailored for maximal fluorescence effect, and not physical plausibilty. While pigments with such a bright and markedly monochromatic fluorescence effect exist (go to a disco and look at the makeup of some of the teenagers there ;-), some of our attempts do not look right under daylight. The aubergine-coloured torus and cylinder are the most problematic in this respect, since such extreme colour changes between blacklight and normal illumination are apparently not common in real life. |
Disclaimer: yes, we know these images are not very aesthetically pleasing, partly because of the garish pigment colours under blacklight. They're proof-of-concept stuff. We're engineers, after all, and we are primarily in the trade of making technical stuff that artists might want to use, and not to fiddle with perfect scenes ourselves. Once we've got nicer pictures, we'll put them here ASAP.
