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Surface Scattering

Surface Scattering in KostaCLOUD

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Lambertian Scattering Model

Used for extremely diffusive surfaces. Perfect hemispherical scatter distribution.

Validity

  • Isotropic Surface Roughness
  • Ideal Diffuser.
  • Only valid for perfectly diffusing materials.

BSDF

Where β = sin(θscatter), β0= sin(θscatter) where R is the reflectivity of the sample.

Example Values

These values below were provided by the reference below, and re-presented here. These values are built into the "Simplistic Presets", where the idea of this table for this model in Rich Pfisterer's words: "Approximated Scatter Model"

SurfaceR
Ideal diffuser1
Typical matte paper at normal incidence0.85
Typical diffuse black paint at normal incidence0.5
Perfect absorber0

References

  1. J. E. Harvey, Understanding surface scatter phenomena: A linear systems formulation, SPIE Press, Bellingham (2019).
  2. Approximated Scatter Models for Stray Light Analysis, Richard N. Pfisterer

ABg Scattering Model

Used for approximating smooth surface finishes.

Validity

  • Isotropic Surface Roughness
  • RMS Surface Roughness ≪ λ (Smooth Surfaces)
  • Surface Roughness is Bandwidth Limited. I.e. The roughness is not just a single sinusoidal frequency, but a spread of frequencies about some dominant frequency.
  • Simplistic Model, Ideal for quick turn-around. Wavelength dependence, and model parameters may differ from reality.

BSDF

Where β = sin(θscatter), β0= sin(θscatter) with some fitting parameters: A,B, and g.

Example Values

These values below were provided by the reference below, and re-presented here. These values are built into the "Simplistic Presets", where the idea of this table for this model in Rich Pfisterer's words: "Approximated Scatter Model"

PolishgBA
Super2.50.000011.4 (σλ)2
Slightly better than Standard2.00.00015.46 (σλ)2
Standard1.50.00113.92 (σλ)2
Slightly worse than Standard1.00.0125.51 (σλ)2

References

Approximated Scatter Models for Stray Light Analysis, Richard N. Pfisterer

Bidirectional Scattering Distribution Function (BSDF)

Sum of ABg Parameters. See ABg for more information.

Rayleigh-Rice Scattering Model

References

J. E. Harvey, Understanding surface scatter phenomena: A linear systems formulation, SPIE Press, Bellingham (2019).

Beckmann-Kirchoff Scattering Model

References

J. E. Harvey, Understanding surface scatter phenomena: A linear systems formulation, SPIE Press, Bellingham (2019).

Harvey-Shack Scattering Model

References

J. E. Harvey, Understanding surface scatter phenomena: A linear systems formulation, SPIE Press, Bellingham (2019).

K-Correlation Scattering Model

References

J. E. Harvey, Understanding surface scatter phenomena: A linear systems formulation, SPIE Press, Bellingham (2019).

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