PROSPECT-D and FLUSPECT output at 1 nm resolution (400–2500 nm, 2101 values); MARMIT-2 at 400–2400 nm (2001 values).
PROSPECT-D spectral coefficients use the original
dataSpec_PDB lookup table (Feret et
al. 2017).
FLUSPECT uses the same spectral coefficients as PROSPECT-D with a 59° Fresnel interface half-angle.
FLUSPECT fluorescence emission shape (phi)
is from Optipar2017_ProspectD (van der Tol
/ Vilfan 2016).
MARMIT-2 soil spectra are taken from the Bablet 2016 database (dry measurements only).
Water optical constants from Segelstein (1981) and Buiteveld/Kou/Wieliczka are bundled as resources.
The exponential integral E₁(x) is computed with the Abramowitz & Stegun rational approximation (max error < 2×10⁻⁷), requiring no external library dependencies.
Interpolation operates in parameter space (not spectral space) — each interpolated parameter set produces a physically consistent spectrum via the full radiative transfer computation.
For MARMIT-2, the soil type index (categorical) steps at t=0.5 for two-point and at t=0.33/0.67 for three-point interpolation; the continuous parameters L, eps, d_i are always smoothly blended.