# Gradient biased to black (it seems); why?

Working on the solution for How to use transmissive voxels with color gradients? to be transmissive instead of reflective, I have a problem that I do not understand (Blender 2.79):

The gradient that is meant to be linear does not blend in a linear way in my eyes. Instead the gradient seems biased to wards black or darker colors. Even when I try to apply gamma correction, the gradient does not improve.

As I'm a beginner with blender, it's possible that I mad some mistake due to misunderstanding, so please tell me what I did wrong, and preferably how to fix it.

First here are the colors that should be blended (basically an RGB cube):

And here is how my attempts look:

Remark: The first image on the second row does not match the view angle of the cube in the first row, but the second one does. Finally, this is my node setup (hoping that's enough for the expert to understand):

The result I'd like to see should be as smooth as this if possible:

Unfortunately the emissive version does not have smooth gradients:

• The very first things I tried was to change the value 2.4: It changed the gradient, but not in a way I would expect. (Actually the first row of cubes was created by lowering the value) Unfortunately I don't quite understand what your first comment is saying. Maybe the "feed" for Emission is wrong. – U. Windl Mar 24 '19 at 22:41
• For the answer below. Keep in mind there are your images and the images in the cited example. I am assuming you want the images in the cited example. – atomicbezierslinger Mar 25 '19 at 0:20
• Your first images do not have an external light source. Your last image has an external light source. – atomicbezierslinger Mar 25 '19 at 2:21
• Something like this? i.stack.imgur.com/7lCem.png – user1853 Mar 25 '19 at 2:43
• For sRGB i.stack.imgur.com/ciQH8.png – user1853 Mar 25 '19 at 2:55

In vertex color paint one can see the useful interpolation. This may or may not be useful. If you just want the gradient you could vertex color paint simple planes and use them as textures. Blender Render. Arrow indicates required setting.

For your example try to avoid negative coordinates relative to origin.

Nodes with exponent of 1. Origin of cube in center of cube. Image above. Negative Values possible for coordinates. Not desirable for your goals.

Origin of cube is in the corner. Image Above. Zero or Positive Values for coordinates. This origin works with your goals.

Make sure your placement of the cube has

one corner at (0,0,0) and origin is there as well.

one corner at (1,1,1)

You may want to research Barycentric Interpolation

• As even your examples do not show a smooth gradient of colors, I'm beginning to suspect that there is a deficit in Blender preventing smooth color gradients for emissive colors. I found out that I'm getting a bit closer when moving the "Material Output"'s input from "Surface" to "Volume", but still I'm not satisfied with the interpolation. Why is it seemingly so much easier to get a smooth gradient with reflective material than with emitting material? – U. Windl Mar 26 '19 at 21:55
• On Dimension and Location: Doesn't the "Vector Transform" map the coordinates independent of position and size? – U. Windl Mar 26 '19 at 22:12