Question

Lots of questions:
1. If 10 people stand around an object (diffuse reflection) and they are the same distance away from the object. Will they see the same image if we ignore the effect of perspective? (include color, intensity, shape and so on)
2. How do we calculate the intensity of lights that are reflected? What information do we need to know?

Answer 1

3. If they all see the same image (question 1) and I want the calculate the light for all direction. Does it mean I can choose a group of light from a random direction and copy this group of light for other directions? Well. I just looked at an object from all direction (question 1), it looks almost the same but some area will have different intensity if I change my viewpoint. Does it mean I need to calculate for all directions?
4. Usually if we want to calculate the whole image that will be formed, do we do it by separate a beam of light into single light rays and do the calculation? Or is there any better method?
5. If we use the method that mentioned in question 4 and we want to calculate for diffuse reflection, how small does a light ray need to be? We can't even really see the roughness with our eyes unless we use microscope.
6. When we say two waves are coherent, do we also refer that they have same amplitude?
7. I found polarization of light hard to understand. How could a light ray have secondary direction? It is a line, not a plane. Though I know light is lots of wave and we can convert it into a plane but isn't there any method to deal with polarization of light with light ray?
8. What is the different between scattering and diffuse reflection?
9. Isn't thin films interference just reflection? Is there any interference?
10. There are many types of scattering. If I want to run a simulation for real world, do i need to simulate all types of scattering?

Answer 2

@PsiSquared @Vincent-Lyon.Fr :Hey :)
Everybody, help me please!

Answer 3

1. everyone will "see" something different, but the brain will sort of "even out" colours, shape, as it knows what to expect.
2. no idea. It depends on the nature , roughness, etc of the surface itself. You can measure reflectance, but you can hardly predict it.
3. this is not clear. Are you into computer simulated images? If so, explain what your aim actually is.
4. 5. no idea
6. no. Coherent means constant phase difference for a time greater than the receptor's integration time.
7. polarisation is just about how the E vector in the EM wave will point, not the direction in which the wave travels. E field is perpendicular to the wave direction of propagation, just as the wave on a string shows displacements of individual points at right angles to the rope itself.
8. diffuse reflection is just one kind of scattering.
9. thin films interference are interferences between 2 reflected waves, one by the upper boundary, one by the lower boundary.
10. depends what you want to do in the end (see 3.)

Answer 4

@Vincent-Lyon.Fr: Thank you very much for answering my questions.
3. Yes. Just simulation.
7. Sorry I don't understand. What is E vector? Is it a plane? Can a plane be expressed by vector? If it is a line, how could we determine if it is travel horizontally/vertically or not?

Answer 5

E or \(\vec E\) is the electric field of the electromagnetic wave.
Have a look at: http://en.wikipedia.org/wiki/File:Electromagneticwave3D.gif
where you can see the propagation of the electric and magnetic fields of a wave.

Answer 6

Ok. I see. So if vector E match the direction of polarizer then it will be polarized. Am I right? Well, that is actually a determination of plane as we can see the wave forms a plane but I want to save the wave as a vector like a light ray. If I do this, can I still calculate for polarization?

Answer 7

@Vincent-Lyon.Fr:
I now have one more question but could you response for my last reply please?
And answer my new question please. Thank you!

Everybody+ @PsiSquared:
Question 11: When we talk about transmission of light, do we mean the light just past? In reality, will the light just pass or refracted a little bit?

Answer 8

Some more questions:
12: Is scattering a method of calculate diffuse reflection? Or is it a condition for reflection to happen (like Rayleigh Scattering). If not, what exactly is it?
13: If scattering is a method of calculate diffuse reflection on object, will we get the same result if we just use law of reflection to calculate diffuse reflection?
14: I think all the light our eyes received are caused by diffuse reflection. Why is there scattering? I can understand Rayleigh Scattering and I think it is the condition for reflection to happen in molecule but how about other scattering?