I would like to define a 3d, spherically symmetric, profile for objects that changes colour and loses opacity as move away from the centre. Essentially I want a 3d heat map centred on the object. The idea is that if I place many of these objects near each other, than they will blend seamlessly, i.e. that instead of overlapping, the space in between them will get the colour and opacity that is the sum of the two.

Is this possible in blender?

Edit for some figures:

So, firstly what I'd like to is paste a 3d profile on to all my objects. Something like this but in 3d:A Gaussian profile

I'd like the opacity to follow the same or a similar gradient as the colour in the above image. So that you can kind of see through the edges of the objects, but not the centre.

Then I'd like to add many objects but I'd like them to combine like this:A double Gaussian profile

Notice how one object doesn't overlap the other, rather they blend seamlessly, and the brightness at points between them is the sum of the brightnesses from each individually.

  • $\begingroup$ Could you illustrate with examples or existing images what you mean, it may be difficult for someone to help only with a verbal description of what you want. It sounds like you are trying to do some sort of volumetric 3D Voronoi map. There are procedural textures for that in Blender, namely the Voronoi texture that can be used as density texture for a volume material, but I am not sure you would get the kind of control you seem to want from it. $\endgroup$ – Duarte Farrajota Ramos Mar 28 '16 at 23:56

First, give each of your objects a white volumetric emission shader. The strength doesn't really matter that much as long as you use the same material on every object so the relative density is consistent.

For the objects themselves I am using a collection of Metaballs. Meta-objects will "blend" into each other similarly to what you are describing.

enter image description here

Now set set your background color to black and render. This will result in the following black and white map.

enter image description here

Next jump over to the compositor to remap this to the color gradient you want. First plug the render into a Normalize node to remap the range of the render to [0,1]. Now run that output through a Color Ramp node and set up whatever gradient you want.

I also found that it gives a result closer to your reference images if you also add a small amount of blur.

enter image description here

The result looks like this:

enter image description here


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