Lecture 13: Global Illumination & Path Tracing (21)
LinyueSong
In case anyone forgot what sr is: It's solid angle; the ratio of the subtended area on sphere to radius squared.
ksaralle
here i see that the numerator is a radiance value whereas the denominator is an irradiance value. it's not 100% clear to me why the irradiance of incoming light is used when we are trying to compute the reflected light from each incoming direction?
phoebeli23
I can't wrap my head around the unit 1/sr. Is there an intuitive explanation for this?
crystal-zq-wang
Does the BRDF vary according to what material or appearance we want to render, and in what ways? Is it just based on previous calculations of properties like radiance pertaining to that particular material?
o0WeiyuFeng0o
@ crystal My thought is that BRDF is used to measure or represent the out coming irradiance at each direction for a given material. Different materials will definitely have different BRDF. The value of BRDF is that once we have it for one material, we could use it to calculate the outcoming light at any given lighting condition, and hence generate realistic rendering.
nobugnohair
Is BRDF similar to pdf in terms of its unit? Because we have to integrate it over dw so we will need an extra factor of 1/dw to cancel it out, which is why we use dE instead of dL in the denominator.
In case anyone forgot what sr is: It's solid angle; the ratio of the subtended area on sphere to radius squared.
here i see that the numerator is a radiance value whereas the denominator is an irradiance value. it's not 100% clear to me why the irradiance of incoming light is used when we are trying to compute the reflected light from each incoming direction?
I can't wrap my head around the unit 1/sr. Is there an intuitive explanation for this?
Does the BRDF vary according to what material or appearance we want to render, and in what ways? Is it just based on previous calculations of properties like radiance pertaining to that particular material?
@ crystal My thought is that BRDF is used to measure or represent the out coming irradiance at each direction for a given material. Different materials will definitely have different BRDF. The value of BRDF is that once we have it for one material, we could use it to calculate the outcoming light at any given lighting condition, and hence generate realistic rendering.
Is BRDF similar to pdf in terms of its unit? Because we have to integrate it over dw so we will need an extra factor of 1/dw to cancel it out, which is why we use dE instead of dL in the denominator.