[Bf-committers] Realistic materials question (Farsthary)

[echelon at infomail.upr.edu.cu]

Hi all :)

 I've being making some researches and tests in the path tracer and as a
result now are required fewer samples per pixel to achieve a desired
level compared to my previous implementation. Off course , for pure path
tracers that´s very dependant on the scene but in general are required 5
times less samples.
 A scene where before need 1000 spp now perform at similar level at 200 spp.

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

  Many small projects 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.

  For example:

  Blinn-Phong model------------>  kd + ks*(H.nor)^n have 3 parameters kd,ks,n
  Modified Blinn-Phong model--->  kd/PI + ks*(n+2)*(nor,H)^n/(2*PI) also
have 3 parameters

 what I mean is what are the ever needed material properties for a BxDF
model? here I'm very open to ideas, suggestions,papers,links and so :)

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

   Perhaps there´s already a well established plan for include physically
based materials in blender in the future but I could not wait for that
and although the Path tracer project could not became a candidate for
official integration in the future it could ease the way for other
projects so I should start implementing it in a very basic way :)

                                   I´m waiting for help

                           Cheers to all and thanks in advance