Inspired by great Marble renders and Shader hack by Lee Griggs. I’ve decided to recreate some tricks with different render engines, a little render Comparison.
The basic idea, using a glass shader for outter shell and an inner sphere with textured volume to fake depth. this way, you will save a lots of work with actually modeling the inner part of a marble. Spectral renderer don’t use this kind of trickery they can actully the inner part as real glass medium (using textures).
I’ve use Cycles (Blender), Renderman, Arnold, Octane and Indigo Renderer. I’ve tried to create a Marvel in Redshift, but i could make it work with single texture and 2 spheres. For Redshift you need actually model a marvel to get realistic rendering.
the spectral rendere engines was the fastest by far. that’s because with spectral render I used a medium instead of volume for interia, that’s saves a lot of render time.
here is quick test with single glass object with Indigo and Cycles :
this here are glass spheres with regular solid texture spheres inside:
I’ve tested RenderMan with spline rendering. it’s much faster compared with baked Geometry. the spline primitives are very good in Renderman.
I’ve stopped the test with mantra after 10 minutes, it is super slow even with optimized render settings.
the Renderman images rendered for 3:20 on a 6 core Xeon 2.7ghz with pxr pathtracer. 4k resolution
rendering splines directly saves a lot disk space and meshing time. interactive rendering was super responsive.
Octane 2019.2 renderings is very fast, I’ve used the geo to render it. 2 minutes, as except its lot faster the CPU renderings. the spline rendering in octane does features custom width yet.
Octane gives physical correct shading out of the box. Renderman the shading is extreme flexible with NPR renderings, which is hard to get in Octane. the IPR responsibility was a little slow with shader tweaks.
rendered with Arnold in Houdini. I’ve tried the atmosphere volumes the first time. easy to setup. The render time was quite slow on the volumes, typically for volumes, but much faster then render the screen envr with VDB cloud. I’ve used a mesh light for inner character illumination.
it’s a shame I could not use Arnold 6 GPU, because its missing features. Volumes would boost get huge speed boost with volume raymarching on a GPU. I had to use a denoiser from Affinity Photo in dark areas.
with Arnold 6 GPU it does not drop any errors, you have to wait 1-2 minutes if data is loaded to GPU and starts the rendering or not. even a wrong file pass to an Hdri image makes Arnold GPU drop out, you sitting and wait in front of a black screen and don’t know if it will render or not.