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3
votes
2answers
132 views

What's the meaning of partial derivative for radiance?

The definition of radiance is: $$L\equiv\frac {\partial^2 \Phi}{\partial A\,\partial\omega\,\cos\theta}$$ where: $\Phi$ is the radiant flux $\omega$ is the solid angle $A\cos\theta$ is the ...
0
votes
1answer
33 views

A few questions about the definition of the BRDF

Hi everyone (I'm sorry for my bad english) I was reading the book "Physically-based rendering" and I came across the definition of the BRDF : $ f(x,\theta, \psi) = dL(x\rightarrow\theta)/dE(x\...
3
votes
0answers
54 views

Energy dependence of integrating dosimeters

The graph shows the relative response of a dosimeter at different energies, normalized to 1.25 MeV Co-60 gamma rays. Curve A is the graph of the equation $$ \frac{\bigg(\frac{r}{X}\bigg)_\bar{E}}{\...
1
vote
0answers
24 views

Geometric and radiometric distribution of light

I'm studying the behavior of the light in a scene, to know how much light arrives at a specific point of a surface and how much of it leaves from the point. From the documentation I'm reading, it says ...
1
vote
0answers
54 views

Hemisphere irradiance

How do I calculate sky irradiance from radiance (L) from a hemisphere above a surface which is tilted relative to the normal (x=0,y=0,z=1). I have L as a function of zenith (0 to 180deg) and azimuth (...
0
votes
0answers
23 views

Irradiance from a light bulb hitting spheres

I'm reading a book saying that irradiance is W/m^2. It continues: For the point light source example in Figure 5.6, irradiance at a point on the outer sphere is less than the irradiance at a ...
0
votes
0answers
7 views

How can I measure radiance?

I'd like to measure radiance in order to see how accurate the Lambertian, Phong models are and maybe to measure the "shininess constant" of a material (which appears in the Phong Model) on some ...
0
votes
0answers
38 views

Remote sensing reflectance

I am not getting something simple for reflectance for a lambertian surface when dealing with remote sensing applications. I am trying to derive the equation from http://landsathandbook.gsfc.nasa.gov/...
0
votes
0answers
64 views

Why do some materials follow Lambert's cosine law?

I perfectly understand Lambert's cosine law, so I can apply it, it isn't really that hard (now that I got it :) $$I_n=I_\theta*\cos\theta$$ What I don't understand is why some materials follow this ...