Help with lights, transparency and colors

I have made a dodecahedron with a cube inside and a tetrahedron inside the cube. What are the parameters I must use so all three objects are seen?
4 in 6 in 12 glass.3dm (136.7 KB)

You need to start by boolean differencing the cube and tetrahedron out of the dodecahedron (with the delete=no option), the the tetrahedron from the cube (delete=no again) so that the objects are not occupying the same space.

Then create a dark background for your render and place a light panel to each side of the objects to provide some illumination on them. Where you have changed the IOR settings, go back to the glass norm of 1.52 or thereabouts - 12 is outside the range of natural materials. If you want an accurate IOR then you’ll find tables of values on the web.

But just a word of warning. In Rhino 6 the stock Render tool is not going to give great results. Raytraced didn’t work for me on your objects, but I’m sitting at an aging laptop which I wouldn’t normally render on, so it might work for you. Rhino 7 is much better for this. See, for example, POLL - Which image do you prefer?

It improved a lot. Thanks.
I was trying to reproduce a drawing from Leonardo da Vinci

that appears in the book by Luca Pacioli “La Divina Proporción”. Do you think you can make it look like the picture that I attach?

The drawing uses no IOR at all, that is, all set to 1. Not a physical representation unless the objects are hollow with extremely thin walls (i.e. IOR of one in raytracing)



Here’s a quick and dirty approximation to what it might look like in reality (not what you are asking for, but interesting because it is so different from Leonardo’s simple drawing):

Notice how the ruby tetrahedron floods the other solids and overwhelms their pale colours. Rendered in R7 cycles.

This is what I got:

4 in 6 in 12 boolean dif backg solid c light.3dm (250.9 KB)
What do you say about the lights?

Sorry, don’t have time for proper look just now, but one thing to take note of: your scene is upside down, so skylight is coming from the bottom of your picture, not the top. Rotate the view so the Z axis points up.

Thanks again. I don’t know why it’s been so difficult for me to learn this.

You can only really learn it by experiment: move a light, see what effect it has; change the brightness, see what effect that has; change a spotlight for a panel light, and so on. Trouble is, you have to render after each change to see the effect, so it is a slow process.

Keep it simple to start. I like this setup with just two rectangular panel lights and a contrasting backdrop (the last a simple surface made by extruding a suitable curve) and with sun and skylight turned off:

If the render is washed out dial down the brightness and/or move the lights further away. If dark, do the opposite.

As you get comfortable with this it will become more instinctive. You can start adding more lights (but don’t overdo it, 2 to 5 is generally right). Check out resources on studio lighting for photographers - you want to place your lights the way they do. Place a few simple shapes like cubes and spheres in a scene and try different materials on them to see how they interact with lighting.


Just going back to @pascal’s point about the IOR being 1 in Leonardo’s drawing.
Here is a render with IOR = 1 (for all three materials):

It’s very flat, with nothing characteristic of glass. Setting IOR to 1.1 doesn’t introduce a lot of distortion, but does start to lift the image and makes it look more 3D:

And of course, at IOR = 1.5 it exhibits real complexity:

And a footnote on IOR: there is scope for only one IOR value per material and that is normally the air to material value. There is no scope for an IOR for the interface between two materials, as you have between, say, tetrahedron and cube. That means Cycles can’t calculate the correct ray path at this interface so the render is actually not physically accurate. The workaround for this is to leave a minimal gap between the two materials, e.g. by shrinking the tetrahedron by the smallest amount you can. That way you get a material/air interface immediately followed by an air/material one and Cycles can use the two air/material IORs.