class Subsurface_Facet_BRDF_Model
The class Subsurface_Facet_BRDF_Model calculates the
scattering from large scale roughness of a substrate under
a smooth dielectric overcoat. The flakes are assumed to
have a specified slope distribution function. The model is
similar to Facet_BRDF_Model, except
that the facets are assumed to be beneath a refracting
interface. The model also can be applied to the scattering
from flakes embedded in a dielectric coating.
Parameters:
| Parameter | Data Type | Description | Default |
|---|---|---|---|
| lambda | double | Wavelength of the light
in vacuum [µm]. (Inherited from BRDF_Model.) |
0.532 |
| type | int | Indicates
whether scattering is evaluated in reflection (0) or
transmission (1). (Inherited from BRDF_Model.) |
0 |
| substrate | dielectric_function | The
optical constants of the substrate, expressed as a
complex number (n,k) or, optionally, as a function of
wavelength. (Inherited from BRDF_Model.) |
(4.05,0.05) |
| sdf | Slope_Distribution_Function | Function
describing the isotropic two-dimensional distribution
of surface slopes. (Inherited from Facet_BRDF_Model.) |
Exponential_Slope_Distribution_Function |
| stack | dielectric_stack | Description of any stack
of films deposited on the substrate, usually specified
by a file. The films are assumed to be conformal and of
total thickness much less than the horizontal scale of
the roughness. See dielectric_stack, for more information. (Inherited from Facet_BRDF_Model). |
no films |
| overcoat | dielectric_function | The optical constants of the coating above the rough surface, expressed as a complex number (n,k) or, optionally, as a function of wavelength. The coating's absorption coefficient (k) must be zero. | (1.59,0.0) |
| overcoat_stack | dielectric_stack | Description of any stack
of films deposited on top of the coating, usually
specified by a file. The films are assumed to be
conformal and to not be rough. See dielectric_stack, for more information. |
no films |
See also:
SCATMECH Home, Conventions, Facet_BRDF_Model, dielectric_stack
T.A. Germer and M.E. Nadal, " Modeling the appearance of special effect pigments," in Surface Scattering and Diffraction for Advanced Metrology, Z.-H. Gu and A.A. Maradudin, Eds., Proc. SPIE 4447, in press (2001).
T.A. Germer and E. Marx, "Ray model of light scattering by flake pigments or rough surfaces with smooth transparent coatings," Appl. Opt. 43(6), 1266-1274 (2004).
Include file:
#include "flake.h"
Source code:
flake.cpp
Definition of public elements:
class Subsurface_Facet_BRDF_Model : public Facet_BRDF_Model { virtual double local_angle(double thetai,double thetas,double phis); virtual double local_slope(double thetai,double thetas,double phis); };
virtual double local_angle(double thetai,double thetas,double phis)
A function which returns the local angle of incidence on a surface facet. It overloads the function of the same name provided by Facet_BRDF_Model.
virtual double local_slope(double thetai,double thetas,double phis)
A function which returns the local slope of a surface facet reflecting in the specified geometry. It overloads the function of the same name provided by Facet_BRDF_Model.
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Current SCATMECH version: 6.00 (February 2008)
This page first online: Version 3.00 (December 2001)
This page last modified: Version 6.00 (February 2008)