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soohark

hmm, how hard is it to extend this to recreate other lens effects like lens flare, bokkeh, and chromatic abberations? For example, with chromatic abberations I think I could do it by sending three seperate rays for rgb values and deflecting them at slightly different angles.

wmonroe

It looks like people have done these in previous years' final projects (one example is here). Bokkeh could be added simply by modifying the shape of the aperture (in Assignment 3 we assumed a circular aperture). Sending R, G, and B at slightly different angles would be a reasonable approximation; real chromatic aberration would create smoothly varying fringes for continuous spectra, which would require modeling the entire visible part of the spectrum instead of just R/G/B channels.

The link above goes into detail about lens flare. The most prominent effect can be created by modeling the realistic lens as a Fresnel reflector, with both reflection and transmission (we only allowed transmission). This gives the series of circles/hexagons that one normally notices in an image with lens flare. The student who did this project also added an element that I probably would not have thought to include: if the light is bright enough, you can see the diffraction of the light around the aperture in addition to internal reflections in the lens apparatus. This produces an interesting starburst effect that doesn't appear with reflection alone.