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T_DIFFUSEBINOMIAL

 

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Description

Data structure for a Diffuse Binomial scatter model.  The diffuse binomial scatter model has the following mathematical form:

 

 

The value of imax is the following:

 

Value of imax

Condition

m

m > 0

|m| - k

(m < 0) and (|m| > k)

0

All other cases

 

In all cases, imax is always non-negative and the summation i = 0 to imax always has at least one value (i=0) where the summation occurs.

 

The parameters U, V, W and T have the following meaning, where (a0,b0) is the specular direction and (a,b) is the scatter direction.  Note that the binomial model is a special plane-symmetric form of the generic polynomial BSDF.

U = a2 + b2

V = aa0 + bb0

W = a02 + b02

T = (a-a0)2 + (b-b0)2 = U - 2V + W

 

Definition

Type T_DIFFUSEBINOMIAL

Name As String

Description As String

ApplyRefl As Boolean

ApplyTrans As Boolean

HaltIncident As Boolean

n As Long

m As Long

L As Long

lMode As Long

lp As Long

D As String

End Type

 

Members

Name

Name of the model.

 

Description

Description of the model.

 

ApplyRefl

Determines if the scatter model is applied on reflection.

 

ApplyTrans

Determines if the scatter model is applied on transmission.

 

HaltIncident

Determines if the scatter model halts the incident ray.

 

n

Upper summation index (see equation above).

 

m

Upper summation index (see relationship to imax in equation above).

 

L

  Upper summation index (see l equation above).

 

 

lMode

This value toggles the interpretation mode of the summation index limits for the polynomial.  For historical reasons, there are three summation modes (values 0-2).  Options are the following:

lMode

Description

0

Default mode for FRED versions newer than 12.60, which is consistent with the summation convention used by other analysis programs.

1

Legacy mode that is used in FRED versions prior to 11.51

2

Summation mode used between versions 11.51 and 12.60

 

lp

Lower summation index (see l' in the equation above).

 

D

Constant (see d in the equation above).

 

 

Used as Parameter in

AddDiffuseBinomial

GetDiffuseBinomial

InitDiffuseBinomial

SetDiffuseBinomial

 

Examples

Scatter

 

 

 

 

 

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