SOME NEW RENDERING THINGS

Had some r&d time lately, at work and at home. Here’s what I’m up to:

I’d like to get the node system hooked up to raytracing, allowing one to do advanced shading techniques but without being forced to do it with the dodgy ‘mixing materials’ method. As a starting point, I’ve made a reflection node - the bonus is that the node system makes it a lot easier to texturise inputs. Thanks to some hints from Alfredo de Greef, I’ve added an additional input to rotate the anisotropic direction (with black being 0° and white being 360°). This can give some nice effects:

• Radial blend texture (node setup)
• Spun-brushed steel (node setup same as above but using this texture instead)
• Carbon fibre (node setup)
• Weird sphere (using a clouds texture for aniso rotation)

I’d also like to include a refract node, an AO node, and/or also a general purpose raytrace node that takes a •vector and •solid angle as input, and gives as output: •whether it intersected something (average of samples in solid angle) •distance to intersection, •shaded colour of intersected face, etc.

At the studio we might possibly be doing a project that would involve vfx/image based lighting. It’s Christmas soon and there are plenty of shiny balls around, so I got a nice one and we’ve started making some HDRI light probes. Blender’s brute force method of doing image based lighting by evenly sampling the hemisphere in AO gives reasonable results, but it’s too slow for animation.

I’ve been looking into a technique originally devised for realtime graphics, based on the paper An Efficient Representation for Irradiance Environment Maps. It works by storing the irradiance in the map in spherical harmonics coefficients and only supports lambert diffuse shading, but it’s extremely fast, and can give quite nice results especially combined with it in an AO source, or even just humble buffer shadows. I’ve done some tests so far with Paul Debevec’s free light probes

• Beach
• Campus
• Grace Cathedral
• and the stairwell at work ;)

Rather than shoehorning it into AO, I’ve so far got a separate Image Based Lighting panel with this in it, and perhaps some other kinds of importance sampling methods later on.