Lecture 13: Global Illumination & Path Tracing (30)
muuncakez
when rendering global illumination with respect to colors do we only need to consider what is reflected since this is what is ultimately "seen" and we can otherwise omit what is being absorbed ...? (like I don't need to know the ocean absorbs the colors red, green, etc. just that its reflecting the color blue?)
does color representation change base on the material (e.i. a glass cup and a clay cup reflect the exact same pink light but are perceived as different pinks bc of the different material) and does absorption play a roll in that? if so, how do we account for this? is it already accounted for in the reflected radiance?
KevinXu02
I think objects reflect the light that it do not absorb, so considering the reflection itself contains some of the information of absorbing in a simple scene.And actually the color we see is a combination of lights of different wave length, so when objects absorb differently, there color appear differently.
marilynjoyce
I feel like in graphics we mostly only consider reflected and refracted light right? Since those are the light rays we actually end up seeing? Like when a light source hits an object, if it were real life, some of it would be absorbed and the other part of it would be reflected or refracted. But I don't know if absorption matters for rendering, that's a good question.
buggy213
almost all of the concepts we discussed are actually wavelength-dependent - in particular, brdfs, radiance, emission, etc. should all have an additional input $$\lambda$$ denoting which wavelength we are considering (we can treat them separately if there isn't interaction between wavelengths, i.e. fluorescence). it happens to be the case that for most graphics applications, it makes most sense to just consider R, G, and B. true spectral renderers do exist which consider a whole range of wavelengths in order to achieve a more physically accurate result, but the improvement is not really worth the extra cost when doing things in realtime.
randyen
Something that I really like about this concept is how intuitive it is based on real life reflections. One thing that I am curious about is how the recursion eventually terminates when calculating either the reflected or incoming radiance (in terms of the logic and math behind it).
when rendering global illumination with respect to colors do we only need to consider what is reflected since this is what is ultimately "seen" and we can otherwise omit what is being absorbed ...? (like I don't need to know the ocean absorbs the colors red, green, etc. just that its reflecting the color blue?)
does color representation change base on the material (e.i. a glass cup and a clay cup reflect the exact same pink light but are perceived as different pinks bc of the different material) and does absorption play a roll in that? if so, how do we account for this? is it already accounted for in the reflected radiance?
I think objects reflect the light that it do not absorb, so considering the reflection itself contains some of the information of absorbing in a simple scene.And actually the color we see is a combination of lights of different wave length, so when objects absorb differently, there color appear differently.
I feel like in graphics we mostly only consider reflected and refracted light right? Since those are the light rays we actually end up seeing? Like when a light source hits an object, if it were real life, some of it would be absorbed and the other part of it would be reflected or refracted. But I don't know if absorption matters for rendering, that's a good question.
almost all of the concepts we discussed are actually wavelength-dependent - in particular, brdfs, radiance, emission, etc. should all have an additional input $$\lambda$$ denoting which wavelength we are considering (we can treat them separately if there isn't interaction between wavelengths, i.e. fluorescence). it happens to be the case that for most graphics applications, it makes most sense to just consider R, G, and B. true spectral renderers do exist which consider a whole range of wavelengths in order to achieve a more physically accurate result, but the improvement is not really worth the extra cost when doing things in realtime.
Something that I really like about this concept is how intuitive it is based on real life reflections. One thing that I am curious about is how the recursion eventually terminates when calculating either the reflected or incoming radiance (in terms of the logic and math behind it).