About realistic materials…

Hi all 🙂

I’ve been making some researches and tests in the path tracer and as a result fewer samples per pixel (spp) are required now to achieve a desired level compared with my previous implementation. Of course , for pure path tracers that´s very dependent on the scene but in general 5 times less samples are required. A scene where 1000 spp were needed before performs now at similar level at 200 spp.

The algorithm handles very well diffuse surfaces, now is the time to tackle reflective and refractive surfaces and it’s where some questions arise :

Many small projects of path tracers around the web are designed to work with a very specific BRDF model, or support only few BRDF implementations, but since the design of the Russian Roulette (if we want to account for those effects because pure statistics diminish small probability states like specular reflections ) should be tailored to certain parameters of a light scatter model, in order to design a general Russian Roulette I need to implement a physically based material with all the parameters needed for BxDF functions.

also I need good formulas for implementing tonemappers because path tracer images fall outside the (0,1) range.

Tonemapped image with exrtools
Tonemapped image with exrtools
Direct renderer image 480 spp Time 5 min 49s
Direct renderer image 480 spp Time 5 min 49s

the show must go on 🙂

About realistic materials…

3 thoughts on “About realistic materials…

  1. atti says:

    that looks very promising!

    it would be great, if one could save the render as HDRI (EXR) and do the tonemappnig in the composite or have the option to tonemap it automagically.


  2. zombiejohn says:

    There’s a tone-map node in the compositing node system. Really it would be best to allow for default access to the unclipped render output, that’s more in line with blender’s render engine as a whole, and every user has their own method for dealing with tone-mapping and gamma solutions.


  3. My greatest appreciation to this community and to the owner and members of this blog. I really appreciate your unity, you cooperation, and your love to the subject of this blog.


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