refmod.hapke.functions.phase#

??? info “References”

1. Cornette and Shanks (1992). Bidirectional reflectance of flat, optically thick particulate systems. Applied Optics, 31(15), 3152-3160. <https://doi.org/10.1364/AO.31.003152>

Module Contents#

refmod.hapke.functions.phase.PhaseFunctionType#
refmod.hapke.functions.phase.double_henyey_greenstein(cos_g, b=0.21, c=0.7)#

Calculates the Double Henyey-Greenstein phase function.

Parameters:

  • cos_g (npt.NDArray) – Cosine of the scattering angle (g).

  • b (float, optional) – Asymmetry parameter, by default 0.21.

  • c (float, optional) – Backscatter fraction, by default 0.7.

Returns:

Phase function values.

Return type:

npt.NDArray

refmod.hapke.functions.phase.cornette_shanks(cos_g, xi)#

Calculates the Cornette-Shanks phase function.

Parameters:

  • cos_g (npt.NDArray) – Cosine of the scattering angle (g).

  • xi (float) – Asymmetry parameter, related to the average scattering angle. Note: This xi is different from the single scattering albedo w.

Returns:

Phase function values.

Return type:

npt.NDArray

References

Cornette and Shanks (1992, Eq. 8).

refmod.hapke.functions.phase.phase_function(cos_g, type, args)#

Selects and evaluates a phase function.

Parameters:

  • cos_g (npt.NDArray) – Cosine of the scattering angle (g).

  • type (PhaseFunctionType) – Type of phase function to use. Valid options are: - “dhg” or “double_henyey_greenstein”: Double Henyey-Greenstein - “cs” or “cornette” or “cornette_shanks”: Cornette-Shanks

  • args (tuple) – Arguments for the selected phase function. - For “dhg”: (b, c) where b is asymmetry and c is backscatter fraction. - For “cs”: (xi,) where xi is the Cornette-Shanks asymmetry parameter.

Returns:

Calculated phase function values.

Return type:

npt.NDArray

Raises:

Exception – If an unsupported type is provided.