Lafortune Lobe (blLfrtn)

key: blLfrtn

type: CCCCC

  1. color: scale factor to apply to this lobe
  2. color: Cx coefficients
  3. color: Cy coefficients
  4. color: Cz coefficients
  5. color: exponents

Description

An implementation of a single lobe of the Lafortune BRDF representation, as described in the 1997 SIGGRAPH paper, Non-linear approximation of reflectance functions, by Eric P. F. Lafortune et al. In general, several lobes (often 3) will be needed, as well as a Lambertian (blLmbrtn) lobe, all as part of an aggregate (smAgg) material.

BRDF

See paper

Examples 

  smAgg			% Lafortune light blue housepaint (from gonioreflectometer measurements)
    blLfrtn
      rgb 1 1 1 end
      rgb 0.870567 0.857255 0.670982 end
      rgb 0.870567 0.857255 0.670982 end
      rgb 0.774290 0.619944 0.586674 end
      rgb 21.820103 18.597755 7.472717 end
    end
    blLfrtn
      rgb 1 1 1 end
      rgb -0.451218 -0.406681 -0.477976 end
      rgb -0.451218 -0.406681 -0.477976 end
      rgb 0.023123 0.017625 0.227295 end
      rgb 3.029342 2.581499 3.677653 end
    end
    blLfrtn
      rgb 1 1 1 end
      rgb -1.031545 -1.029426 -1.026588 end
      rgb -1.031545 -1.029426 -1.026588 end
      rgb 0.706734 0.696530 0.687715 end
      rgb 66.899060 63.767912 57.489181 end
    end
    blLmbrtn
      rgb 0.3264 0.3967 0.7084 end
    end
  end