Materials

Each model has up to four material families (bus, array cells, array back, antennas and others; the names adapt to the model). For each family:

Parameter	Meaning
Albedo	Diffuse (Lambertian) reflectance, 0 to 1
Specular reflectance F₀	Mirror reflectance at normal incidence (Schlick’s Fresnel)
Roughness	Width of the specular lobe (GGX microfacets): low values give sharp glints

Reference library

Material	Albedo	F₀	Roughness
Gold kapton MLI	0.22	0.45	0.38
Silver MLI	0.30	0.70	0.32
White paint	0.80	0.04	0.75
Aged white paint	0.35	0.04	0.80
Beta cloth (ISS modules)	0.70	0.04	0.85
Black paint	0.05	0.04	0.60
GaAs cells + cover glass	0.06	0.05	0.12
Phased-array face	0.14	0.25	0.35
Carbon composite	0.08	0.06	0.40
Aluminium	0.15	0.85	0.28
OSR mirrors (radiator)	0.04	0.90	0.06
Niobium (nozzle)	0.08	0.35	0.35
Ideal Lambertian	0.50	0	1

Measured BRDF

Load a measured BRDF (CSV) replaces the parametric model of one material by a laboratory table.

Prepare the file

Columns theta_i, theta_r, phi (degrees) and brdf (sr⁻¹) or brf. See BRDF CSV.

Load it on a material

The samples are binned into a 48 × 32 table of half-vector angles, which the GPU reads instead of the Lambert + GGX model.

Check the fit

The parametric equivalent (albedo, F₀, roughness) fitted to the samples is shown with its residual. It drives the 3D view and the flash search.

A scale factor multiplies the whole table (ageing, contamination); the Monte-Carlo draws and the automatic fit act on it. See Photometric model for the method.

Uncertainty settings

The Uncertainty section at the bottom of the tab sets the standard deviations of the Monte-Carlo draws.