The CG Labratory.
A playground for experiements, RnD and new tech in 3D graphics.
Here I post test results of experiments I do with no other intention than finding out how things work. I experiment with the unknown, try out new technology and workflows to find what suits me best.
An Arnold rendering utilising custom Fresnel curve driven reflection, HDRI sequence as single light source (2015)
I wanted to do a little animation to check several things with Solid Angles renderer Arnold. I used a HDRI sequence provided by USC Institute for creative Technologies as single and only light source to get the timelapse effect from morning to sunset with its full dynamic range. All materials utilise custom Fresnel curve driven reflections and follow an energy conservation principal. To test a few more things with Arnold I implemented camera projections and displacement for the environment.
In typical Arnold fashion this rendering is a Brute Force Global Illumination rendering that comes with all its pros and cons.
- realisitc lighting (intensitiy, falloff, bounce light)
- physical plausible materials
- easy scene setup
- rendertimes (average of 90min/frame in 2000x1125 on a i7-970 single 6-core CPU @ 3.2Ghz)
- rendering prone to fireflies due to the very high dynamic range of the HDRI and Arnolds unbiased Monte Carlo ray tracing method.
An artist firendly approach on Fresnel curve driven reflection (2015)
Based on the previous results on custom fresnel curves I managed to stay very close to the physical correct result and reduce the harshness of the method. I no longer rely on 3 seperate Fresnel curves for R,G,B but use an averaged unified Fresnel curve to drive the reflection. The specular color parameter of the shader is no longer used by the Fresnel curve and can therefore easily be adjusted by the artist to meet art direction.
This method looses somewhat of its physical correctness but years of experience in the industry have tought me physical correct is not always aesthetically desired.
A physical approach on Fresnel curve driven reflection (2015)
I always wanted to use the correct IOR values, without guesswork, when creating a cg material and now have found a way to do so - physically correct!
The Fresnel curve is based on real world material measurements of the materials refractive index n and the extinction coefficient k at a given wavelength and results in a physically correct BRDF for the aiStandard shader in Arnold. Unfortunatelly at this point this method is highly technical and non-artist-friendly. Art direction is nearly as impossible, as changing the characteristics of the real world material. This method though is the basis for developing a less physical but more artist friendly approach.
Geometry following curves on complex surfaces(2015)
Stitches following complex surfaces can be difficult or tedious so I used ICE in XSI to control the direction and orientation of a generic geometry. The result is a pointcloud that need to be converted into geometry again, with the help of ICE, that then can be exported to Maya for rendering.
Procedural geometry scattering based on Voronoi diagram in ICE (2014)
This is the result of a tutorial I followed. The tutorials you can find here:
Building your own Voronoi scattering effect part1
Building your own Voronoi scattering effect part2
A small collection of CG materials created and rendered in Maya with VRay 3.0 (2014)
CG materials checked in different light situations for physical plausibility. (2014)
My first material setup done in Maya a few years ago in 2010, rendered in Mental Ray.