What does the p stand for in this equation? Is it the length of the ray hitting the surface?
anup-h
@eric99ying It's the point we're evaluating radiance at
anup-h
Does the cos(theta) in this equation derive from Lambert's cosine law? It doesn't seem intuitive that the closer your angle gets to the surface normal, the smaller the radiance gets (since it scales with the inverse of cosine)
henryzxu
It's slightly confusing to me too, but I don't think we're dividing by cos(theta) as much as we're taking the derivative. The equation is calculating how much power there is, per unit solid angle, per unit of projected area. The per unit of projected area is the dAcos(theta). An additional explanation can be found here.
mnicoletti15
In the explanation in the stackoverflow post in that link, it says that omega stands for frequency. Is this true? It seems it should stand for solid angle, right? I am confused about what is being represented by the picture here though -- and I am especially confused about the meaning of the derivative with respect to solid angle
jenzou
To mnicoletti15: ω stands for direction of the ray. It consists of (θ,ϕ) -- Source: page 38 of http://www0.cs.ucl.ac.uk/staff/m.slater/Teaching/LightField/lighting-vrst.pdf
What does the p stand for in this equation? Is it the length of the ray hitting the surface?
@eric99ying It's the point we're evaluating radiance at
Does the cos(theta) in this equation derive from Lambert's cosine law? It doesn't seem intuitive that the closer your angle gets to the surface normal, the smaller the radiance gets (since it scales with the inverse of cosine)
It's slightly confusing to me too, but I don't think we're dividing by cos(theta) as much as we're taking the derivative. The equation is calculating how much power there is, per unit solid angle, per unit of projected area. The per unit of projected area is the dAcos(theta). An additional explanation can be found here.
In the explanation in the stackoverflow post in that link, it says that omega stands for frequency. Is this true? It seems it should stand for solid angle, right? I am confused about what is being represented by the picture here though -- and I am especially confused about the meaning of the derivative with respect to solid angle
To mnicoletti15: ω stands for direction of the ray. It consists of (θ,ϕ) -- Source: page 38 of http://www0.cs.ucl.ac.uk/staff/m.slater/Teaching/LightField/lighting-vrst.pdf