BRDF Shape Function Retrieval

Submitted by Sixsmith Joshua on Fri, 17/05/2019 - 14:41
Short Description

Retrieve the BRDF shape function parameters for each supported spectral band within the acquisition.

For each supported spectral band within an acquisition to be processed, retrieve the BRDF shape function parameters, Alpha-1 and Alpha-2.

The spatial extent of the acquisition in native Coordinate Reference System (CRS) units is projected into the Sinusoidal CRS of the MCD43A1 data.  Once projected, the Isometric, Volumetric and Geometric albedo parameters are retrieved for the area of interest, for each of the acquisitions supported spectral bands, from the relevant spectral bands of the MCD43A1 data and aggregated.

The results are then transformed into the BRDF Shape function, labelled as Alpha-1 and Alpha-2, by the following ratio's:

  • Alpha-1 = Volumetric / Isometric
  • Alpha-2 = Geometric / Isometric

If the spectral band for the acquisition has a wavelength broad enough to cover multiple MODIS spectral bands, then averages are taken from all derived Alpha-1 and Alpha-2 parameters, before returning single pair of Alpha-1 and Alpha-2 BRDF shape function parameters.