Materials and light transport
Posted 07 April 2012 - 02:17 PM
I appreciate your help Reedbeta.
Posted 07 April 2012 - 11:32 PM
This should work correctly, but if you have a variety of lights of different powers in your scene, it will produce photons with a variety of different powers. As mentioned earlier in the discussion about reflection, having photons with a variety of different powers increases the noise in the rendered result and requires you to shoot more photons or render for longer to get a smooth result. So, it's better to distribute photons proportional to the power of the lights, so that high-power lights shoot more photons than low-power ones; then the photons can all be the (roughly) the same power. This is very similar to the reflection probability method we just discussed in this thread, as well as the triangle area probability we talked about in another thread, so you should be able to figure it out if you feel like taking this on...
Posted 08 April 2012 - 12:13 AM
So if I have 3 lights of diffrent powers, say, 10, 35 and 60, the idea is to shoot 10 photons for the first light, 35 for the next and 60 for the last, each with identical 'power'? as oppose to shoot the same number of photons for all lights and adjust the photon power for each light?
Posted 08 April 2012 - 02:44 AM
When I trace after shooting all the photons, if I hit a light, how would this work now with lights of diffrent power and area?? Do I simply return lightColor * PI * lightArea?
Posted 08 April 2012 - 04:46 AM
Posted 09 April 2012 - 03:44 AM
I'm all confused now Reedbeta
Hope you have a great Easter, and thanks for your patience with me!
Posted 09 April 2012 - 01:52 PM
In your reply #24, that's how I do it. But at trace time, if I hit a light, do I also return the light color?
Posted 09 April 2012 - 04:42 PM
Posted 09 April 2012 - 05:40 PM
When you trace back, rays that hit a light return lightColor, but aren't they going to look all at the same intensity? Say, if one light source shoot 50 photons, and they other one shoot 100 photons, it's like a 50w and 100w, so ins't the 50w be reduced so that it looks not as bright as the 100w?
Posted 09 April 2012 - 05:51 PM
a. They might be the same color (equal intensity) but the first one has 1/2 the surface area of the other
b. They might be the same area but the first one has 1/2 the intensity of the other
c. Some other possibility (e.g. the first one is 2x the area and 1/4 the intensity, or whatever).
Power is a combination of intensity and area, but when you hit a light source with a ray, it cares only about intensity, not about area. Photons care about power, so they care about both intensity and area.
Posted 09 April 2012 - 06:06 PM
Posted 09 April 2012 - 07:38 PM
Posted 10 April 2012 - 01:55 AM
So if you're saying that a 100w should be vec3(1,1,1) and the 50w should be vec3(0.5,0.5,0.5) then it's not going to work because we will be shooting 100 photons at vec3(1,1,1) and 50 photons at vec3(0.5,0.5,0.5) when we should shoot photons all at vec3(1,1,1).
Posted 10 April 2012 - 07:38 AM
1 user(s) are reading this topic
0 members, 1 guests, 0 anonymous users