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I'd like to render a publication quality image something like the image below. I'll script the whole process so we can build many different structures without having to redraw everything, and probably animate it as well.

I'll want to be able to rotate the camera and the light source independently to view from any angle, so I need some kind of illumination/shader combination that keeps the whole sphere well diffusely lit no mater where the "Sun" is placed.

They all seem to have a similar diffuse shader with some specular component; we can see the reflection of a narrow light source or Sun on every atom, but they don't shadow each other, and there is some source of diffuse illumination as well, there's no night/dark line where "the Sun don't shine" i.e. on the very bottom-right edge.

Question: What kind of illumination and/or shader use to produce these 3D ball-and-stick atomic structure models that show specular reflection but don't have shadows, and will be viewable from any direction?

To maintain flexibility/compatibility with future projects I'm assuming I should ask for a solution for the cycles rendering engine, but I supposed I can be talked out of it.


Phys.org' Electrons falling flat: Germanium falls into a 2-D arrangement on zirconium diboride shows a ball-and-stick model of a somewhat complicated 3D arrangement of atoms.

The blue atoms are germanium (light blue ones stick up above the others), green is zirconium and orange are boron.

Electrons falling flat: Germanium falls into a 2-D arrangement on zirconium diboride

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  • $\begingroup$ TBH the quality of the image is pretty bad. Looks like simple phong shading to me. Adding a principled shader, setting the specular component to 1 and the roughness to around 0.2 should do it: i.stack.imgur.com/k92TZ.jpg $\endgroup$
    – brockmann
    Apr 24 at 11:35
  • $\begingroup$ @brockmann Doesn't there need to be more than a single light to make this work well, especially with the need to be able to view from any angle and vary the position of the "Sun"? The question explains that I need to do more than just reproduce this static image. I don't want the back sides of the atoms to be black. $\endgroup$
    – uhoh
    Apr 24 at 11:44
  • $\begingroup$ Oops. To get rid of the hard shadows I'd suggest set the enviroment to white and you instantly get a better and especially a more realistic result: i.stack.imgur.com/YKiCJ.jpg $\endgroup$
    – brockmann
    Apr 24 at 12:14
  • $\begingroup$ @brockmann okay I'll look into it. These get progressively darker near the edge, whereas yours get brighter near the edge, but that may be addressable through choice of diffuse shader and its settings, and whatever that environment is it needs to look black to the camera, not light. $\endgroup$
    – uhoh
    Apr 24 at 12:43
  • $\begingroup$ Yeah, sure... Again, I really don't get why the provided image should be any serious reference image for scientifc visualization. It's most likely rendered with default settings of 3ds max 5 scanline render engine around 1998. Just saying that you can get a way better image quality even out of eevee. $\endgroup$
    – brockmann
    Apr 25 at 13:30
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A few steps that might help Cycles render like this:

Lighting:

I find it's usually best to adjust this first, on neutral-grey surfaces

A single key point-light, with ambient fill provided by a somewhat luminous World. The World has one color to contribute to the lighting, and another to appear in the camera, thus:

enter image description here

The size of the point-light will affect the size and softness of the 'ping' specular dot on the spheres.

Object visibility:

You've got to cripple Cycles on the objects, to prevent shadows being cast, and stop any diffuse bounce of light between them. Switching off everything bar 'Camera' visibility seems to work, in the Object Properties tab > Visibility panel:

enter image description here

Materials: For convenience, a Principled shader:

enter image description here

.. with 'Roughness' adjusting size and softness of highlight, and maybe a tweak of 'Specular' intensity. A tiny contribution of 'Emission' in the base color, helps the World fill the away-from-light surfaces.

This sort of result:

enter image description here

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  • $\begingroup$ Okay thank you! Your answer is both illuminating and instructive :-) That "bit of emission" sounds like an unavoidable, necessary "secret sauce" ingredient. In order to be algorithmic and reproducible I usually build everything (including nodes) from script like I show here from several years ago. My old scripts like hat mostly still work with only minor tweaks. $\endgroup$
    – uhoh
    Apr 25 at 0:17
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    $\begingroup$ @uhoh the emission cheat certainly saves manual tweaking, I thought .. maybe a fixed Sun-light could be your fill, instead? Forgot to mention. Maybe it would be worth shading your lights with a Light-Falloff > Constant, to prevent attenuation with distance. $\endgroup$ Apr 25 at 7:19
  • $\begingroup$ Yes I see what you mean. I'll update in a few more says once I take this out for a spin. $\endgroup$
    – uhoh
    Apr 25 at 8:08

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