Hi, I am new here and I've got lots of questions about optics physics. I hope everybody can help me out. First, please check my understanding of diffuse reflection: http://www.physicsclassroom.com/Class/refln/u13l1d6.gif As shown in the diagram, I am sure that it will still follow the law of reflection but light will be reflected back from all different directions as the all the normals have different angle and photon is infinite small which means a beam of light will have infinite number of photons. Therefore, we will see the image no matter from what direction. Am I right so far? If not, please correct me. Question : 1. If 10 people stand around an object (diffuse reflection), with a constant distance to 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? 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 tried to look 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. What cause this? Does it mean I need to calculate for all directions (question 3)? 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? Thank you very much!