HEMR
Name
hemr
Purpose (one Line)
Compute the hemispherical reflectance
Description
This function is coded from equation 12.10 on page 365 in Hapke's book,
"Theory of Reflectance and Emittance Spectroscopy".
Category
Miscellaneous
Calling Sequence
ans = hemr(w,imu,holes,p,b0,theta)
Inputs
w - Single scattering albedo.
imu - Cosine of the incidence angle.
holes - Compaction parameter value (1986 formalism).
p - Parameters of the single particle phase function
(default "function" is a constant of value p, this is not very
useful for this routine and is not recommended).
There are two legal input forms for p:
1. an array of dimensionality Pparms
2. an array of dimensionality (n_elements(w),Pparms)
b0 - Backscatter value.
theta - Surface roughness value. (radians)
Optional Input Parameters
None.
Keyword Parameters
nmu - number of points between 0 and 1 at which to evaluate mu = cos(e).
Default 6.
nphi - number of points between 0 and pi at which to evaluate phi
Default 6.
H93 - Flag passed to bidr2, if set, uses the 1993 version of Hapke's
approximation to the Chandresekar H function. The 1993 version
is more accurate but considerably slower to compute.
Pfn - Flag passed to bidr2. REQUIRED.
Specify function to use for P(g) instead of the default constant.
The function must be a procedure taking arguments g,a,F,/radians
g phase angle in radians (with keyword /radians set)
a an array of Pparms parameters
F phase function evaluated at phase angles g
Use "fn_hg3.pro" as a model.
Pparms- Flag passed to bidr2. Specify number of parameters to be passed to
P(g). Really only needed if the number of parameters isn't one.
pedantic - Flag pased to bidr, if set, returns NaN for w > 1.
Outputs
Return value is the hemispherical reflectance.
Common Blocks
None.
Side Effects
None.
Restrictions
Any input may be a vector. If more than one is a vector then the
lengths must match. The return will have the same dimensions as
the input.
Procedure
Modification History
Written by Leslie Young, SwRI, 2010/12/28, cloned from bidr2 where similar