commit 96e414f7b3cd6454b0ea6f35f30d9071abf34795
parent 254541e21fadb6fd904aa8424d1364cfec03ca4e
Author: Vincent Forest <vincent.forest@meso-star.com>
Date: Fri, 17 Jun 2022 14:29:55 +0200
Add the file format specification
Diffstat:
| A | doc/rnsf.5.scd | | | 131 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 131 insertions(+), 0 deletions(-)
diff --git a/doc/rnsf.5.scd b/doc/rnsf.5.scd
@@ -0,0 +1,131 @@
+rnsf(5)
+
+; Copyright (C) 2022 |Meso|Star> (contact@meso-star.com)
+;
+; This program is free software: you can redistribute it and/or modify
+; it under the terms of the GNU General Public License as published by
+; the Free Software Foundation, either version 3 of the License, or
+; (at your option) any later version.
+;
+; This program is distributed in the hope that it will be useful,
+; but WITHOUT ANY WARRANTY; without even the implied warranty of
+; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+; GNU General Public License for more details.
+;
+; You should have received a copy of the GNU General Public License
+; along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# NAME
+
+rnsf - Rad-Net Scattering Functions file format
+
+# DESCRIPTION
+
+*rnsf* is a text file format that describes a phase function 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
+
+```
+<rnsf> ::= <per-wlen-phase-func>
+ | <per-band-pĥase-func>
+
+---
+
+<per-wlen-phase-func> ::= wavelengths <wavelengths-count>
+ <wlen-phase-func>
+ [ <wlen-phase-func> ... ]
+
+<wlen-phase-func> ::= <wavelength> <phase-func>
+<wavelengths-count> ::= INTEGER
+<wavelength> ::= REAL # In nanometers
+
+---
+
+<per-band-phase-func> ::= bands <bands-count>
+ <band-phase-func>
+ [ <band-phase-func ... ]
+
+<wlen-band-func> ::= <wavelength-min> <wavelength-max> <phase-func>
+
+<bands-count> ::= INTEGER
+<wavelength-min> ::= REAL # In nanometers
+<wavelength-max> ::= REAL # In nanometers
+
+---
+
+<phase-func> ::= <phase-func-hg>
+ | <phase-func-discrete>
+
+<phase-func-hg> ::= hg <asymmetric-param>
+<asymmetric-param> ::= REAL # in [-1, 1]
+
+<phase-func-discrete> ::= discrete <angles-count>
+ 0 <value>
+ [ <per-angle-value> ... ] # In ascending order wrt the angle
+ PI <value>
+<per-angle-value> ::= <theta> <value>
+<theta> ::= REAL # In radian
+<value> ::= REAL # Not necessarily normalized
+
+```
+
+# EXAMPLES
+
+Spectrally varying phase function on two spectral bands: a band for the visible
+part of the spectrum for which a Henyey & Greenstein phase function is used, and
+a band for long waves with a discretized phase function on 4 angles:
+
+```
+bands 2
+
+# Visible part
+380 780 hg 0
+
+# Inrared
+1000 100000 discrete 4
+ 0 0.079577
+ 0.78 0.079577
+ 2.35 0.079577
+ PI 0.079577
+```
+
+Setup a phase function for a set of 10 wavelengths. Use a discrete phase
+runction for short waves and Henyey & Greenstein for long waves:
+
+```
+wavelengths 10
+
+# Short waves
+430 discrete 8
+ 0 0.02
+ 0.23 0.04
+ 0.5 0.07
+ 0.7 0.15
+ 1.54 1.23
+ 1.8 0.02
+ 2 1.23
+ PI 0.79
+450 discrete 2
+ 0 0.5
+ PI 0.796
+750 discrete 2
+ 0 0.079577
+ 0.78 0.079577
+ 2.35 0.079577
+ PI 0.079577
+
+# Long waves
+1100 hg -0.1
+1300 hg 0.57
+1400 hg 0.4
+2100 hg 0.3
+2500 hg -0.9
+2900 hg -0.4
+100000 hg 0.0
+```
