Hello people:
I am using maxwell render 2 with the maya plugin, and while making some sphere tests, i stumbled on this issue.
I don’t really understand why the red green and blue ball won’t be completely white too even though i pushed the parameters of the light and sky to the maximum.
The materials are all the same, just the color changes.
Anyone has an idea why this happens?
Maxwell Render: Color insanity
Pyoo
#1
jtheninja
#2
This is something of a simplification, but think of it this way:
As you increase the background/light color, you are essentially multiplying all your colors by increasingly large numbers. Once all 3 channels go past 1.0, you get an object that clips to white.
But. If you made one or more channels 0, no matter how big of a number you multiply it by, it’s still 0. RGB 0,1,0 x5000 is RGB 0,5000,0, aka still green. This seems a little weird because it never happens in the real world, since nothing will have 0% reflectivity, especially only at certain wavelengths. Which is why you shouldn’t ever use 0 or 1.0 for diffuse color. Bump the saturation down just a tiny bit on the spheres (so the “other” color channels are >0) and you should get the result you expected, at least with a bright enough background.
Pyoo
#3
Thank you Jtheninja!
I think it was indeed the problem, i guess it was an equivalent of the infinite loop you can get in programming.
The parameter that seem to be the bad guy is the Reflectance 0 degree.
Mine was probably too saturated or too bright as you say. Though i noticed that it should be slightly under this 1 value to produce a normal expectation.
I managed to find that in the manual:
Avoid setting the Reflectance 0° color too bright. Setting it to 255 for example means this material will reflect back almost all the light it receives, which does not happen in the real world.
Maxwell Render still keeps the amount of light reflected/ absorbed within physical limits but the result with such high Reflectance values means the light will keep bouncing around in your scene with very little loss in energy, which will produce noisier renders and a washed-out look with very little contrast.
A reasonable setting even for very bright materials would be around 225-235. For example, the Reflectance value of a white piece of paper, when converted to RGB, is around 225. Please note that this only matters for the Reflectance 0° color. The Reflectance 90° color can be left at fully white (RGB 255)
This rule is valid also when using textures for the reflectance 0 - if your texture contains fully white areas use the RGB Clamp setting in the Texture picker to contain the range of brightness in the texture ( set the high value of RGB clamp to lower than 255).