Rendering; Is empty space rendered with same properties as air?

[Anonymous]

I'm wondering about the default behaviour of the rendering engine.

Do empty spaces render with the properties (refractive index) of air?

For realistic raytracing of total internal reflectance would I need to create a body made of air?

[jasonhomrighaus]

I have done this both ways and there do seem to be some differences.

[jasonhomrighaus]

So i decided to play with the a little.

the first image i made using a solid body of air with the table and diamond inside it

the second is just the table and the diamond

the third is an air body that has had the diamond and table cut out of it to create three non interfering bodies

With solid air massWith no air massWith cutout air mass

[Anonymous]

Now this is interesting, because I see some odd or unexpected effects when shining light through two materials that interface but have different refractive indices, and those effects are a bit like what I see in your last image with the air body; these lines and breaks appear.