Quote from: Cyber-Angel on February 09, 2008, 06:34:12 PM
The link you provided talks about Unbiased Renderers and as far as I knew only a renderer based on Spectral Rendering can be unbiased as traditional RGB renderers can not be by there intrinsic nature also with renderers of the RGB type it is impossible for them to do things like Polarization, Spectral Rendering on the other hand is capable of these effects and is if carefully designed Physically Accurate where renderers of the RGB type are not.
Heya Cyber-Angel,
Here's a good, short, and pretty understandable paper on unbiased rendering:
http://www.cs.caltech.edu/~keenan/bias.pdfDISCLAIMER: I'm not posting this to take anything away from maxwell, or to get into a "my renderer's better than yours," I'm just posting to help clarify some things that I think are general misconceptions. I don't intend any of this to be argumentative.
Whether or not a renderer is biased or not is a technical description of the rendering algorithm -- regarding how it accounts for, and where it gets, the information that the renderer uses to do a calculation. The words, "biased" and "unbiased" do not refer to the resultant image and they don't have a lot of bearing on wether or not a renderer is "physically correct." An important point to get here is that even if a renderer is unbiased, it may still produce incorrect images. "Unbiased" doesn't refer to the result of the renderer, only the algorithms used, and an algorithm only needs to stay unbiased within the realm of what it chooses to support.
In my understanding of the definition of "bias", if you have a renderer that supports glass, but it doesn't properly account for all light paths through that glass, you've got a biased renderer. However, if that same renderer handles everything else rigorously but doesn't allow you to even create glass (ie. it doesn't support glass) it can actually be an unbiased renderer.
Another important point is that it's totally possible to produce 100% correct images using biased renderers. Generally, a renderer intentionally uses biased algorithms for performance reasons, not as a mathematical shortcut, or due to misunderstandings, oversights and mistakes made by the programmers -- ie. photon mapping is a biased algorithm, but photons are undeniably fast and they can produce correct images.
Whether or not a renderer is doing it's calculations in RGB or some other way also has no basis on whether or not a renderer is biased or unbiased. You could write an unbiased renderer that only calculates light intensities and produces black and white images -- again, it's a matter of whether or not everything in the scope of the simulation is accounted for in the equations.
As to spectral effects not being possible in an RGB space renderer, that's not true. A renderer that does the majority of it's calculations in RGB can still fully support spectral effects. This is just a guess, but I'd bet that maxwell is actually doing the majority of it's work in RGB space, but supports intelligent spectral effects (otherwise, writing new shaders for it would be a real bear). Brazil r/s runs mostly in RGB space, but it supports spectral effects -- you can actually run glass prism type experiments that produce rainbow caustics and things like that. This image shows some spectral effects via dispersion in glass:
http://brazil.mcneel.com/photos/technology/picture22.aspxQuote from: Cyber-Angel on February 09, 2008, 06:34:12 PMdoesn't Maxwell just treat light as just an EM Wave rather than treating light as it is which is both a particle and a wave
If it did, you could reproduce Young's Double Slit experiment (
http://en.wikipedia.org/wiki/Double-slit_experiment) - which I'm pretty sure you can't do in any production renderer out there
* cptvideo waves at treddi