Global color adjustment for objects?

[Matt]

What are the corresponding values in the exported mtl?

[Mandrake]

#==================================================
#Material list
#This file has been created by PoseRay v3.10.3.412
#3D model to POV-Ray/Moray Converter.
#Author: FlyerX
#Email: flyerx_2000@yahoo.com
#Web: http://mysite.verizon.net/sfg0000/
#==================================================

#==================================================
newmtl Mat
Ns 222.8609
Ka 0 0 0
Kd 0.3529412 0.6039216 0.3098039
Ks 1 1 1
d 1
#r 0
#metal
#blend 0
#cell_hi

[Henry Blewer]

Terragen 2 calculates light a little differently than other 3D apps. Blender for example calculates light in 1 direction until Global Illumination or Ambient Occlusion are turned on. Terragen 2 has Global Illumination turned on by default. This causes the overall lightness of the color values to be higher, because there is light from all directions.
So in essence, you have your sun (spot) light. Plus the ambient/global lighting. I compensate for this when I set up an object in Terragen 2 that I have made. I set up the coloring using the default opening file. I use a multishader. Each material from the object model can be accessed from the multishader. Then I go to the objects node and save it out as a tgo object file. It's now ready for which ever landscape I want, I just import it.

[Matt]

TG halves all diffuse colour values it imports from .mtl files. That sometimes makes them *darker* in TG. However, these values are treated as if they are in linear colour space, so they are not the same values you see in the Windows color picker. The values are converted into a gamma 2.2 space (approximately sRGB) making them lighter when they are viewed in the color picker. This conversion happens so that the colour in the color picker appears as closely as possible to that colour in the final render, otherwise there would be a different set of complaints about the colours. If you're working in another 3D app that doesn't consider conversions between linear and non-linear colour spaces, there will be differences. With TG I decided to interpret the values in the .mtl as linear values, not sRGB values, but that won't be the right decision all the time.

What does the cube look like in a final ray-traced render in C4D? Does C4D have gamma correction applied to the rendered image?

Matt

[Mandrake]

I'll look into your render question, tomorrow.

What do you think about my use of the color adjust node, it would change color on an even keel? As I said before.
Thanks for the explanation Mat.

[Matt]

EDIT:  I was going to say that the colour adjust shader is a good solution, but then I realised a problem. The colour adjust shader is not always able to maintain reflections and some other effects that your default shaders produce. It adjusts diffuse colours and tries its best to keep luminosity as is, but other properties may be lost.

What I would suggest is that you always use textures, leave the material at default white, and figure out a system that allows you to match your textures between apps (which may involve no corrections at all).

Matt

[Henry Blewer]

Thanks Matt. That explanation helps me out also. I was guessing, but found my method worked.
Another thing I do when coloring objects in T2 is give them an obnoxious color to see what part of the object I am working on. Then I make the final color choice.