htrdr
0.9.2
mrumtl(5)
NAME
mrumtl - ModRadUrb MaTeriaL file format
DESCRIPTION
mrumtl is a text file format that describes a Bidirectional Reflectance Distribution Function (BRDF) whose type and parameters can vary spectrally. Its data are described for a set of wavelengths or spectral bands that must be listed in ascending order.
Characters behind the hash mark (#) are considered comments and are therefore ignored, as well as empty lines, i.e. lines without any characters or composed only of spaces and tabs.
GRAMMAR
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<mrumtl> ::= <per-wlen-BRDF> | <per-band-BRDF> --- <per-wlen-BRDF> ::= wavelengths <wavelengths-count> <wlen-BRDF> [ <wlen-BRDF> ... ] <wlen-BRDF> ::= <wavelength> <BRDF> <wavelengths-count> ::= INTEGER <wavelength> ::= REAL # in nanometer --- <per-band-BRDF> ::= bands <bands-count> <band-BRDF> [ <band-BRDF> ... ] <band-BRDF> ::= <wavelength-min> <wavelength-max> <BRDF> <bands-count> ::= INTEGER <wavelength-min> ::= REAL # Inclusive bound in nanometers <wavelength-max> ::= REAL # Inclusive bound in nanometers --- <BRDF> ::= <BRDF-lambertian> | <BRDF-specular> <BRDF-lambertian> ::= lambertian <reflectivity> <BRDF-specular> ::= specular <reflectivity> <reflectivity> ::= REAL # In [0, 1]
EXAMPLES
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:
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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:
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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