cadcam@inesc.UUCP ( Mario Rui Gomes) (05/29/89)
In the light models that I know of, the only processes of interaction
between light and matter are the reflection and refraction.
What happened to the difraction?
Has anyone, out there, knowledge of any work, or paper, about this subject ?
Thanks...
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Manuel Gamito mcvax!inesc!alf!mag
The recognition of ignorance is the first step towards wisdom.
Viviane to Morgaine in 'The mists of Avalon'djs@mit-amt (David J. Sturman) (05/30/89)
In article <855@inesc.UUCP> cadcam@inesc.UUCP ( Mario Rui Gomes) writes: > >In the light models that I know of, the only processes of interaction >between light and matter are the reflection and refraction. > >What happened to the difraction? > >Has anyone, out there, knowledge of any work, or paper, about this subject ? > Look at Potmesil, Michael and Chakravarty, Indranil. "A Lens and Aperture Camera Model for Synthetic Image Generation." Computer Graphics 15.3 (Proceedings SIGGRAPH August 1981). pp 297-305 or Potmesil, Michael and Chakravarty, Indranil. "Synthetic Image Generation with Lens and Aperture Model." ACM Transactions on Graphics 1.2 April 1982 pp 85-108 The second is a slightly longer version of the first. They describe a method of simulating diffraction through a circular aperture. The paper is interesting and the method is feasible. For a clearer understanding it should be supplemented by a good optics text like Hecht and Zajac or Born and Wolf. Although P&C claim that diffraction effects are important and change the contrast of the final image, they do not demonstrate it. Some studies here at the Media Lab by Alex Petland and also by Michael Bove seem to indicate that although diffraction of monochromatic light may affect the image, diffraction of polychromatic light has little effect (aside from depth of field effects). This has to do with the cancelling effect of the different wavelengths. However, I have yet to see images with and without diffraction effects. We may try it out over the summer. I would add that only diffraction from the lens aperture has been modelled and diffraction from partially obscuring objects in the scene has not. David Sturman Computer Graphics and Animation Group MIT Media Lab djs@media-lab.media.mit.edu