NAMEmrumtl - ModRadUrb MaTeriaL file format
A mrumtl file defines a spectral varying Bidirectional Reflectance Distribution Function (BRDF). Both the parameters and the type of the function can vary over the spectrum. These data can be defined for a list of wavelengths or for a set a spectral bands. In both cases, the wavelengths or the band boundaries are given in nanometers and must be listed in ascending orders. In addition the spectral bands must not overlapped.
Characters behind the hash mark (#) are considered as comments and are thus ignored. Empty lines, i.e. lines without any characters or composed only of spaces and tabulations, are simply skipped.
<mrumtl> ::= <BRDF-list-wlen> | <BRDF-list-band> <BRDF-list-wlen> ::= wavelengths <wavelengths-count> <BRDF-wlen> [ <BRDF-wlen> ... ] <BRDF-list-band> ::= bands <bands-count> <BRDF-band> [ <BRDF-band> ... ] <wavelengths-count> ::= INTEGER <bands-count> ::= INTEGER <BRDF-wlen> ::= <wavelength> <BRDF> <BRDF-band> ::= <band-bound-min> <band-bound-max> <BRDF> <bound-bound-min> ::= <wavelength> <bound-bound-max> ::= <wavelength> <wavelength> ::= DOUBLE # in nanometer <BRDF> ::= <BRDF-lambertian> | <BRDF-specular> <BRDF-lambertian> ::= lambertian <reflectivity> <BRDF-specular> ::= specular <reflectivity> <reflectivity> ::= DOUBLE
Describe a material with only two bands: one for the visible part of the spectrum and one for the long waves. In both cases use a diffuse reflectivity:
bands 2 380 780 lambertian 0.9 # Visible part 1000 100000 lambertian 0.1 # Infrared
Setup a material for a list of 17 wavelengths. This material is diffuse in short waves and specular in long waves:
wavelengths 17 # Short waves 430 lambertian 5.2e-2 450 lambertian 6.2e-2 500 lambertian 6.5e-002 600 lambertian 0.165 750 lambertian 0.175 # Long waves 1100 specular 0.1 1300 specular 0.17 1400 specular 0.1 2000 specular 0.1 2100 specular 0.4 2300 specular 0.18 2500 specular 0.9 2600 specular 0.95 2900 specular 0.4 3000 specular 0.3 4000 specular 0.0 100000 specular 0.0