commit 6f814fcfe54100ea00d183d3b508889234df022a
parent cc52e5d05005a5df2ffba81a14494310542ad1a2
Author: Vincent Forest <vincent.forest@meso-star.com>
Date: Wed, 4 Oct 2023 12:16:08 +0200
Translate htrdr-combustion man page to mdoc
In the course of translation, its content has been updated. In
particular, we have added the missing "EXIT STATUS" section. References
to the MPI 2.0 and OpenMP 2.0 specifications have been added to the new
STANDARDS section. The COPYRIGHT and LICENSE sections have been removed,
as they are not part of conventional Linux manuals (mandoc doesn't
mention them at all). Finally, the entire text has been revised to make
it clearer and more in line with mandoc conventions.
Diffstat:
3 files changed, 633 insertions(+), 5 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -13,4 +13,5 @@ htrdr
htrdr-atmosphere
htrdr-atmosphere.1
htrdr-combustion
+htrdr-combustion.1
htrdr-planeto
diff --git a/Makefile b/Makefile
@@ -573,8 +573,8 @@ install: all
# @$(SHELL) make.sh install "$(DESTDIR)$(PREFIX)/share/man/man5" rnrl.5
@if [ "$(ATMOSPHERE)" = "ENABLE" ]; then \
$(SHELL) make.sh install "$(DESTDIR)$(PREFIX)/share/man/man1" htrdr-atmosphere.1; fi
-# @if [ "$(COMBUSTION)" = "ENABLE" ]; then \
-# $(SHELL) make.sh install "$(DESTDIR)$(PREFIX)/share/man/man1" htrdr-combustion.1; fi
+ @if [ "$(COMBUSTION)" = "ENABLE" ]; then \
+ $(SHELL) make.sh install "$(DESTDIR)$(PREFIX)/share/man/man1" htrdr-combustion.1; fi
# @if [ "$(PLANETO)" = "ENABLE" ]; then \
# $(SHELL) make.sh install "$(DESTDIR)$(PREFIX)/share/man/man1" htrdr-planeto.1; fi
@@ -588,7 +588,7 @@ uninstall:
rm -f "$(DESTDIR)$(PREFIX)/share/doc/htrdr/README.md"
rm -f "$(DESTDIR)$(PREFIX)/share/man/man1/htrdr.1"
rm -f "$(DESTDIR)$(PREFIX)/share/man/man1/htrdr-atmosphere.1"
-# rm -f "$(DESTDIR)$(PREFIX)/share/man/man1/htrdr-combustion.1"
+ rm -f "$(DESTDIR)$(PREFIX)/share/man/man1/htrdr-combustion.1"
# rm -f "$(DESTDIR)$(PREFIX)/share/man/man1/htrdr-planeto.1"
# rm -f "$(DESTDIR)$(PREFIX)/share/man/man5/htrdr-image.5"
# rm -f "$(DESTDIR)$(PREFIX)/share/man/man5/htrdr-materials.5"
@@ -598,7 +598,7 @@ uninstall:
################################################################################
# Man pages
################################################################################
-man: htrdr-atmosphere.1
+man: htrdr-atmosphere.1 htrdr-combustion.1
htrdr-atmosphere.1: htrdr-atmosphere.1.in
sed -e 's/@HTRDR_ATMOSPHERE_ARGS_DEFAULT_OPTICAL_THICKNESS_THRESHOLD@/$(HTRDR_ATMOSPHERE_ARGS_DEFAULT_OPTICAL_THICKNESS_THRESHOLD)/g' \
@@ -620,8 +620,32 @@ htrdr-atmosphere.1: htrdr-atmosphere.1.in
-e 's/@HTRDR_ARGS_DEFAULT_RECTANGLE_SZ@/$(HTRDR_ARGS_DEFAULT_RECTANGLE_SZ)/g'\
$@.in > $@
+htrdr-combustion.1: htrdr-combustion.1.in
+ sed -e 's/@HTRDR_COMBUSTION_ARGS_DEFAULT_LASER_FLUX_DENSITY@/$(HTRDR_COMBUSTION_ARGS_DEFAULT_LASER_FLUX_DENSITY)/g' \
+ -e 's/@HTRDR_COMBUSTION_ARGS_DEFAULT_FRACTAL_DIMENSION@/$(HTRDR_COMBUSTION_ARGS_DEFAULT_FRACTAL_DIMENSION)/g' \
+ -e 's/@HTRDR_COMBUSTION_ARGS_DEFAULT_FRACTAL_PREFACTOR@/$(HTRDR_COMBUSTION_ARGS_DEFAULT_FRACTAL_PREFACTOR)/g' \
+ -e 's/@HTRDR_COMBUSTION_ARGS_DEFAULT_OPTICAL_THICKNESS_THRESHOLD@/$(HTRDR_COMBUSTION_ARGS_DEFAULT_OPTICAL_THICKNESS_THRESHOLD)/g' \
+ -e 's/@HTRDR_COMBUSTION_ARGS_DEFAULT_GRID_DEFINITION_HINT@/$(HTRDR_COMBUSTION_ARGS_DEFAULT_GRID_DEFINITION_HINT)/g' \
+ -e 's/@HTRDR_COMBUSTION_ARGS_DEFAULT_WAVELENGTH@/$(HTRDR_COMBUSTION_ARGS_DEFAULT_WAVELENGTH)/g' \
+ -e 's/@HTRDR_ARGS_CAMERA_PERSPECTIVE_FOV_EXCLUSIVE_MIN@/$(HTRDR_ARGS_CAMERA_PERSPECTIVE_FOV_EXCLUSIVE_MIN)/g' \
+ -e 's/@HTRDR_ARGS_CAMERA_PERSPECTIVE_FOV_EXCLUSIVE_MAX@/$(HTRDR_ARGS_CAMERA_PERSPECTIVE_FOV_EXCLUSIVE_MAX)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_CAMERA_PERSPECTIVE_FOCAL_DST@/$(HTRDR_ARGS_DEFAULT_CAMERA_PERSPECTIVE_FOCAL_DST)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_CAMERA_PERSPECTIVE_FOV@/$(HTRDR_ARGS_DEFAULT_CAMERA_PERSPECTIVE_FOV)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_CAMERA_PERSPECTIVE_LENS_RADIUS@/$(HTRDR_ARGS_DEFAULT_CAMERA_PERSPECTIVE_LENS_RADIUS)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_CAMERA_POS@/$(HTRDR_ARGS_DEFAULT_CAMERA_POS)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_CAMERA_TGT@/$(HTRDR_ARGS_DEFAULT_CAMERA_TGT)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_CAMERA_UP@/$(HTRDR_ARGS_DEFAULT_CAMERA_UP)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_IMG_WIDTH@/$(HTRDR_ARGS_DEFAULT_IMG_WIDTH)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_IMG_HEIGHT@/$(HTRDR_ARGS_DEFAULT_IMG_HEIGHT)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_IMG_SPP@/$(HTRDR_ARGS_DEFAULT_IMG_SPP)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_RECTANGLE_POS@/$(HTRDR_ARGS_DEFAULT_RECTANGLE_POS)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_RECTANGLE_TGT@/$(HTRDR_ARGS_DEFAULT_RECTANGLE_TGT)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_RECTANGLE_UP@/$(HTRDR_ARGS_DEFAULT_RECTANGLE_UP)/g' \
+ -e 's/@HTRDR_ARGS_DEFAULT_RECTANGLE_SZ@/$(HTRDR_ARGS_DEFAULT_RECTANGLE_SZ)/g'\
+ $@.in > $@
+
clean_man:
- rm -f htrdr-atmosphere.1
+ rm -f htrdr-atmosphere.1 htrdr-combustion.1
################################################################################
# Miscellaneous targets
@@ -651,3 +675,4 @@ lint: htrdr-atmosphere.1
shellcheck -o all make.sh
mandoc -Tlint -Wall htrdr.1 || [ $$? -le 1 ]
mandoc -Tlint -Wall htrdr-atmosphere.1 || [ $$? -le 1 ]
+ mandoc -Tlint -Wall htrdr-combustion.1 || [ $$? -le 1 ]
diff --git a/htrdr-combustion.1.in b/htrdr-combustion.1.in
@@ -0,0 +1,602 @@
+.\" Copyright (C) 2018-2019, 2022-2023 Centre National de la Recherche Scientifique
+.\" Copyright (C) 2020-2022 Institut Mines Télécom Albi-Carmaux
+.\" Copyright (C) 2022-2023 Institut Pierre-Simon Laplace
+.\" Copyright (C) 2022-2023 Institut de Physique du Globe de Paris
+.\" Copyright (C) 2018-2023 |Méso|Star> (contact@meso-star.com)
+.\" Copyright (C) 2022-2023 Observatoire de Paris
+.\" Copyright (C) 2022-2023 Université de Reims Champagne-Ardenne
+.\" Copyright (C) 2022-2023 Université de Versaille Saint-Quentin
+.\" Copyright (C) 2018-2019, 2022-2023 Université Paul Sabatier
+.\"
+.\" 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/>.
+.Dd September 29, 2023
+.Dt HTRDR-COMBUSTION 1
+.Os
+.Sh NAME
+.Nm htrdr-combustion
+.Nd simulate radiative transfer in a combustion medium
+.Sh SYNOPSIS
+.Nm
+.Op Fl fhINsv
+.Op Fl C Ar persp_camera_opt Ns Op : Ns Ar persp_camera_opt ...
+.Op Fl D Ar laser_flux_density
+.Op Fl d Ar dump_type
+.Op Fl F Ar rdgfa_opt Ns Op : Ns Ar rdgfa_opt ...
+.Op Fl g Ar combustion_chamber_opt Ns Op : Ns Ar combustion_chamber_opt...
+.Op Fl i Ar image_opt Ns Op : Ns Ar image_opt ...
+.Op Fl l Ar laser_opt Ns Op : Ns Ar laser_opt ...
+.Op Fl O Pa cache
+.Op Fl o Pa output
+.Op Fl P Ar ortho_camera_opt Ns Op : Ns Ar ortho_camera_opt ...
+.Op Fl R Ar flux_sensor_opt Ns Op : Ns Ar flux_sensor_opt ...
+.Op Fl T Ar optical_thickness
+.Op Fl t Ar threads_count
+.Op Fl V Ar accel_struct_definition
+.Op Fl w Ar laser_wavelength
+.Fl m Pa medium_geometry
+.Fl p Pa thermo_properties
+.Fl r Pa refractive_ids
+.Sh DESCRIPTION
+The purpose of
+.Nm
+is to perform radiative transfer computations in a scene representing a
+semi-transparent combustion medium enlightened by a laser sheet.
+The medium may be surrounded by solid boundaries
+.Pq inner limits of the combustion chamber .
+The program will currently compute, in the visible at a given frequency, the
+monochromatic image or the radiative flux density of the combustion medium:
+collected light comes from the laser, and is scattered by soot aggregates
+within the flame before eventually reaching the sensor.
+.Pp
+Data relating to the gaseous medium are stored on the vertices of an
+unstructured tetrahedral mesh: pressure, temperature and concentrations
+of H2O, CO2 and CO are provided for each vertex.
+In the visible range, these data are useless, since the gas is assumed
+to be transparent, but they are part of the data expected to anticipate
+future developments in the longwave domain.
+.Pp
+Soot optical properties are computed using the Rayleigh-Debye Gans theory, for
+Fractal Aggregates (RDG-FA).
+This requires the knowledge of: soot volumic fraction, soot number
+density (number of primary particles per aggregate) and primary
+particles diameter, for each vertex of the tetrahedral mesh.
+For any position in the volume, these quantities are first interpolated
+from the values retrieved at the nodes of the current tetrahedron, and
+are then interpolated for the position of interest.
+Which then makes possible to compute the absorption and scattering
+cross-sections of soot aggregates, as well as their scattering function.
+.Pp
+The Monte-Carlo algorithm that accounts for the visible intensity is inspired
+from the algorithm used for solar radiation in
+.Xr htrdr-atmosphere 1 .
+It was adapted to partially illuminated scenes in order to solve
+onvergence issues.
+.Pp
+In
+.Nm
+the spatial unit 1.0 corresponds to one meter while the
+estimated monochromatic radiances and flux densities are saved in
+W/sr/m^2 and
+W/m^2 respectively.
+The results are written to the output file if the
+.Fl o
+option is set and otherwise to standard output.
+The output image is a list of raw ASCII data formatted using the
+.Xr htrdr-image 5
+file format.
+.Pp
+.Nm
+implements mixed parallelism.
+On a single computer (that is, a node), it uses shared memory
+parallelism while it relies on Message Passing Interface (MPI) to
+parallelize calculations between multiple nodes.
+.Nm
+can therefore be launched either directly or via a process launcher such
+as
+.Xr mpirun 1
+to distribute the calculation on several computers.
+.Pp
+The options are as follows:
+.Bl -tag -width Ds
+.It Fl C Ar persp_camera_opt Ns Op : Ns Ar persp_camera_opt ...
+Set up a pinhole or thin-lens perspective camera.
+.Pp
+The options for a perspective camera are as follows:
+.Bl -tag -width Ds
+.It Cm focal-dst= Ns Ar distance
+Distance to focus on with a thin lens camera, that is, a camera whose
+.Cm lens-radius
+is not zero.
+The default focal distance is
+@HTRDR_ARGS_DEFAULT_CAMERA_PERSPECTIVE_FOCAL_DST@ meters.
+.It Cm focal-length= Ns Ar length
+Focal length of a camera lens.
+It is another way to control the field of view of a thin lens camera.
+By default, the field of view is set through the
+.Cm fov
+parameter.
+.It Cm fov= Ns Ar angle
+Vertical field of view of the camera in
+]@HTRDR_ARGS_CAMERA_PERSPECTIVE_FOV_EXCLUSIVE_MIN@,
+@HTRDR_ARGS_CAMERA_PERSPECTIVE_FOV_EXCLUSIVE_MAX@[ degrees.
+The default field of view is
+@HTRDR_ARGS_DEFAULT_CAMERA_PERSPECTIVE_FOV@ degrees.
+.It Cm lens-radius= Ar radius
+Radius of the camera lens.
+A non-zero radius means that the camera is a thin lens camera while a
+zero radius defines a pinhole camera.
+The default lens radius is
+@HTRDR_ARGS_DEFAULT_CAMERA_PERSPECTIVE_LENS_RADIUS@.
+.It Cm pos= Ns Ar x , Ns Ar y , Ns Ar z
+Camera position.
+Default is @HTRDR_ARGS_DEFAULT_CAMERA_POS@.
+.It Cm tgt= Ns Ar x , Ns Ar y , Ns Ar z
+Targeted position
+Default is @HTRDR_ARGS_DEFAULT_CAMERA_TGT@.
+.It Cm up= Ns Ar x , Ns Ar y , Ns Ar z
+Upward vector that the top of the camera is pointing towards.
+Default is @HTRDR_ARGS_DEFAULT_CAMERA_UP@.
+.El
+.It Fl D Ar laser_flux_density
+Laser flux density in W/m^2. Default is
+@HTRDR_COMBUSTION_ARGS_DEFAULT_LASER_FLUX_DENSITY@.
+.It Fl d Ar dump type
+Write the data defined by
+.Ar dump_type
+to
+.Pa output
+instead of performing a normal calculation.
+.Pp
+The
+.Ar dump_type
+values supported are as follows:
+.Bl -tag -width Ds
+.It Cm laser
+Write the geometry of the laser sheet in legacy VTK format.
+.It Cm octree
+Write the leaves of the space partitioning structures used to speed up
+radiative transfer calculations.
+Each leaf stores the minimum and maximum extinction coefficients of the
+tetrahedra it covers.
+Data are written in legacy VTK format.
+.El
+.It Fl F Ar rdgfa_opt Ns Op : Ns Ar rdgfa_opt ...
+RDG-FA phase function parameters.
+.Pp
+The parameters of the RDG-FA phase function are as follows:
+.Bl -tag -width Ds
+.It Cm dimension= Ns Ar real
+Fractal dimension.
+Default is @HTRDR_COMBUSTION_ARGS_DEFAULT_FRACTAL_DIMENSION@.
+.It Cm prefactor= Ns Ar real
+Fractal prefactor.
+Default is @HTRDR_COMBUSTION_ARGS_DEFAULT_FRACTAL_PREFACTOR@.
+.El
+.It Fl f
+Force overwriting of
+.Pa output
+file.
+.It Fl g Ar combustion_chamber_opt Ns Op : Ns Ar combustion_chamber_opt...
+Define the combustion chamber.
+.Pp
+Note that the combustion chamber does not prevent the camera from seeing
+the medium, nor the laser from illuminating the medium, even if either is
+outside the chamber.
+The rendering algorithm ensures that they are not occluded by the
+combustion chamber, like with a two-way mirror.
+When the laser is out of chamber, its emissive surface is seen as if it
+were following its interior surface.
+Likewise, the radiance seen by the camera outside the chamber is the
+radiance that reaches it as if its image plane were following the
+surface of the geometry.
+.Pp
+The combustion chamber options are as follows:
+.Bl -tag -width Ds
+.It Cm mats= Ns Ar materials
+Combustion chamber materials saved in
+.Xr htrdr-materials 5
+format.
+.It Cm obj= Ns Ar mesh
+Combustion chamber geometry saved in
+.Xr htrdr-obj 5
+format.
+.Pp
+In accordance with the
+.Xr htrdr-obj 5
+file format, the mesh interface must be defined as a fine interface,
+i.e. it must be composed of 3 elements separated by the
+.Li \&:
+character.
+By convention,
+.Nm
+expects the external environment to be called "air" and the medium
+inside the combustion chamber to be called "chamber".
+No assumptions are made about the name of the surface material, except
+that it must refer to a valid material.
+.El
+.It Fl h
+Display short help and exit.
+.It Fl I
+Use an isotropic phase function rather than the RDG-FA phase function
+.Pq option Fl F .
+.It Fl i Ar image_opt Ns Op : Ns Ar image_opt ...
+Configure sensor image.
+.Pp
+The image options are as follows:
+.Bl -tag -width Ds
+.It Cm def= Ns Ar width Ns x Ns Ar height
+Image definition.
+Default is
+@HTRDR_ARGS_DEFAULT_IMG_WIDTH@x@HTRDR_ARGS_DEFAULT_IMG_HEIGHT@.
+.It Cm spp= Ns Ar samples_per_pixel
+Number of samples to solve the Monte Carlo estimation of each pixel.
+Default is @HTRDR_ARGS_DEFAULT_IMG_SPP@.
+.El
+.It Fl l Ar laser_opt Ns Op : Ns Ar laser_opt ...
+Laser emission surface.
+.Pp
+The laser options are as follows:
+.Bl -tag -width Ds
+.It Cm pos= Ns Ar x , Ns Ar y , Ns Ar z
+Center of the laser emission surface.
+Default is @HTRDR_ARGS_DEFAULT_RECTANGLE_POS@.
+.It Cm tgt= Ns Ar x , Ns Ar y , Ns Ar z
+Targeted position, i.e.\&
+.Cm tgt No - Cm pos
+is the normal of the laser surface.
+Default is @HTRDR_ARGS_DEFAULT_RECTANGLE_TGT@.
+.It Cm up= Ns Ar x , Ns Ar y , Ns Ar z
+Upward vector that the top of thr laser is pointer towards.
+Default is @HTRDR_ARGS_DEFAULT_RECTANGLE_UP@.
+.It Cm sz= Ns Ar width , Ns Ar height
+Size of laser surface in meters.
+Default is @HTRDR_ARGS_DEFAULT_RECTANGLE_SZ@
+.El
+.It Fl m Ar medium_geometry
+Tetrahedra of the combustion medium saved in
+.Xr smsh 5
+format.
+.It Fl N
+Pre-calculate tetrahedron normals.
+This option should speed up the calculation since normals are calculated
+once per tetrahedron rather than being re-evaluated each time a
+tetrahedron is interrogated at a given position.
+On the other hand, the storage required by these normals increases the
+memory footprint.
+.It Fl O Pa cache
+File where acceleration structure is stored/loaded.
+If the
+.Pa cache
+file does not exist, it is created and filled with the acceleration
+structure constructed from the medium geometry
+.Pq option Fl m ,
+termodynamic properties
+.Pq option Fl p
+and refractive indices
+.Pq option Fl r
+input files.
+This cached data can then be reused in subsequent executions, provided
+that the input files supplied to the command are the same as those used
+to set up the cache, thus considerably speeding up the pre-processing
+stage.
+.Pp
+If
+.Pa cache
+contains data generated from input files that are not those submitted on
+the command line, an error is notified and execution is aborted, thus
+avoiding the use of bad cached data.
+.It Fl o Pa output
+Output file.
+If not defined, data is written to standard output.
+.It Fl P Ar ortho_camera_opt Ns Op : Ns Ar ortho_camera_opt ...
+Set up an orthographic camera.
+.Pp
+The options for an orthographic camera are as follows:
+.Bl -tag -width Ds
+.It Cm height= Ns Ar lenght
+Image plane height.
+Its width is calculated from this length and the image ratio
+to guarantee square pixels
+.Pq see Fl i No option .
+.It Cm pos= Ns Ar x , Ns Ar y , Ns Ar z
+Camera position.
+Default is @HTRDR_ARGS_DEFAULT_CAMERA_POS@.
+.It Cm tgt= Ns Ar x , Ns Ar y , Ns Ar z
+Targeted position.
+Default is @HTRDR_ARGS_DEFAULT_CAMERA_TGT@.
+.It Cm up= Ns Ar x , Ns Ar y , Ns Ar z
+Upward vector that the top of the camera is pointing towards.
+Default is @HTRDR_ARGS_DEFAULT_CAMERA_UP@.
+.El
+.It Fl p Ar thermo_properties
+Thermodynamic properties of the combustion medium saved in
+.Xr atrtp 5
+format.
+.It Fl R Ar flux_sensor_opt Ns Op : Ns Ar flux_sensor_opt ...
+Set up a flux sensor.
+.Pp
+The flux sensor options are as follow:
+.Bl -tag -width Ds
+.It Cm pos= Ns Ar x , Ns Ar y , Ns Ar z
+Sensor center.
+Default is @HTRDR_ARGS_DEFAULT_RECTANGLE_POS@.
+.It Cm tgt= Ns Ar x , Ns Ar y , Ns Ar z
+Targeted position.
+Default is @HTRDR_ARGS_DEFAULT_RECTANGLE_TGT@.
+.It Cm up= Ns Ar x , Ns Ar y , Ns Ar z
+Upward vector that the top of the sensor is pointing towards.
+Default is @HTRDR_ARGS_DEFAULT_RECTANGLE_UP@.
+.It Cm sz= Ns Ar width , Ns Ar height
+Sensor size in meters.
+Default is @HTRDR_ARGS_DEFAULT_RECTANGLE_SZ@.
+.El
+.It Fl r Ar refrative_ids
+Refrative indices of the combustion medium as a function of wavelength,
+saved in
+.Xr atrri 5
+format.
+.It Fl s
+Use Single Instruction Multiple Data (SIMD) instruction sets if available.
+This should speed up calculation time.
+.It Fl T Ar optical_thickness
+Optical thickness used as threshold criterion for building the acceleration
+structure.
+Default is @HTRDR_COMBUSTION_ARGS_DEFAULT_OPTICAL_THICKNESS_THRESHOLD@.
+.It Fl t
+Indication of the number of threads to be used.
+By default,
+.Nm
+uses many threads as processor cores.
+.It Fl V Ar accel_struct_definition
+Definition of the discrete field storing the upper limit of the
+radiative coefficients from which the acceleration structure is built.
+The extent of the grid corresponds to the axis aligned bounding box of
+the combustion medium.
+.Pp
+The definition can be established as follows:
+.Bl -tag -width Ds
+.It Ar x , Ns Ar y , Ns Ar z
+Define grid definition on X, Y and Z axes.
+.It Ar expected_definition
+Provide an expected definition of the grid along its longest axis.
+The definition along the two remaining axes is then calculated
+internally to tend towards cubic cells.
+This is the default behavior with an expected definition set to
+@HTRDR_COMBUSTION_ARGS_DEFAULT_GRID_DEFINITION_HINT@.
+.El
+.It Fl v
+Make
+.Nm
+verbose.
+.It Fl w Ar laser_wavelength
+Laser wavelength in nanometers, which is also the wavelength at which
+calculations are performed.
+Default is @HTRDR_COMBUSTION_ARGS_DEFAULT_WAVELENGTH@.
+.El
+.Sh OUTPUT IMAGE
+Images calculated by
+.Nm
+are saved in
+.Xr htrdr-image 5
+format.
+This section describes the nature and arrangement of image data
+depending on the type of calculation performed.
+.Ss Shortwave monochromatic image
+For a monochromatic image rendering, the expected value and the standard
+deviation of the pixel radiance (in W/sr/m^2) are saved on the first and
+the second components.
+All other components are unused excepted the seventh and eighth
+components that store the estimate of the radiative path computation
+time in microseconds and its standard error.
+.Ss Shortwave flux density map
+A flux density map
+.Pq option Fl R
+store on its first and second component
+the expected value and the standard error of the pixel radiative flux
+density
+.Pq in W/m^2 .
+All other components are unused excepted the seventh and eighth
+components that store the estimate of the radiative path computation
+time
+.Pq in microseconds
+and its standard error.
+.Sh EXIT STATUS
+.Ex -std
+.Sh EXAMPLES
+Make
+.Nm
+verbose
+.Pq option Fl v
+and render an image of a combustion medium whose tetrahedral mesh is
+stored in
+.Pa tetra.smsh
+and whose associated thermodynamic properties are recorded in
+.Pa thermprops.atrtp .
+Refractive indices are listed in
+.Pa refract_ids.atrri .
+The laser's surface emission center is positioned at the origin and its
+direction aligned with the Y axis
+.Pq option Fl l .
+The calculated image resolution is
+.Ar 800 No by Ar 600
+pixels
+.Pq option Fl i
+and the monochromatic radiance
+of each pixel is estimated at
+.Ar 500
+nanometers
+.Pq option Fl w
+with
+.Ar 64
+Monte Carlo realisations
+.Pq option Fl i .
+The resulting image is written to
+.Pa output
+unless the file already exists, in which case an error is notified, the
+program stops and the output file remains unchanged:
+.Bd -literal -offset Ds
+htrdr-combustion -v \\
+ -m tetra.smsh \\
+ -p thermprops.atrtp \\
+ -r refract_ids.atrri \\
+ -l pos=0,0,0:tgt=0,1,0:up=0,0,1:sz=0.001,0.2 \\
+ -w 500 \\
+ -C pos=0.06,0,0.01:tgt=0.05,0,0.01:up=0,0,1:fov=30 \\
+ -i def=800x600:spp=64 \\
+ -o output
+.Ed
+.Pp
+Add a combustion chamber to the previous example
+.Pq option Fl g :
+its mesh is defined in
+.Pa chamber.obj
+while its materials are listed in
+.Pa materials.mtls .
+Save the acceleration structure in
+.Pa octree.cache
+or reuse it if it has already been filled in a previous run with
+compatible input data.
+Set the finest resolution of this acceleration structure to
+.Ar 1000
+voxels along the main extension of the medium
+.Pq option Fl V
+and use an optical
+thickness criterion of
+.Ar 5
+to build it
+.Pq option Fl T .
+Use the
+.Fl f
+option to force
+overwriting of the
+.Pa output
+file if it exists, and use the
+.Fl s
+option to accelerate rendering with available SIMD instruction sets:
+.Bd -literal -offset Ds
+htrdr-combustion -v \\
+ -m tetra.smsh \\
+ -p thermprops.atrtp \\
+ -r refract_ids.atrri \\
+ -g obj=chamber.obj:mats=materials.mtls \\
+ -l pos=0,0,0:tgt=0,1,0:up=0,0,1:sz=0.001,0.2 \\
+ -w 500 \\
+ -C pos=0.06,0,0.01:tgt=0.05,0,0.01:up=0,0,1:fov=30 \\
+ -i def=800x600:spp=64 \\
+ -O octree.cache \\
+ -V 1000 \\
+ -T 5 \\
+ -fo output \\
+ -s
+.Ed
+.Pp
+Calculate a flux density map
+.Pq option Fl R .
+The sensor on which the flux density is calculated is a square with
+sides measuring
+.Ar 0.05
+meters.
+Its center is placed at the origin and points towards the Z axis.
+The flux density map has a resolution of
+.Ar 500 No by Ar 500
+pixels
+.Pq option Fl i .
+The flux density per pixel is estimated with
+.Ar 64
+realisations; the flux density for the entire sensor is therefore
+calculated with 16 million realizations (500*500*64):
+.Bd -literal -offset Ds
+htrdr-combustion -v \\
+ -m tetra.smsh \\
+ -p thermprops.atrtp \\
+ -r refract_ids.atrri \\
+ -l pos=0,0,0:tgt=0,1,0:up=0,0,1:sz=0.001,0.2 \\
+ -w 500 \\
+ -R pos=0,0,0:tgt=0,0,1:up=0,1,0:sz=0.05,0.05 \\
+ -i def=500x500:spp=64 \\
+ -O octree.cache \\
+ -V 1000 \\
+ -T 5 \\
+ -fo map.txt
+ -s
+.Ed
+Write a representation of the acceleratrion structure in
+.Pa accel_struct.vtk
+.Pq option Fl d :
+.Bd -literal -offset Ds
+htrdr-combustion -v \\
+ -m tetra.smsh \\
+ -p thermprops.atrtp \\
+ -r refract_ids.atrri \\
+ -O octree.cache \\
+ -d octree \\
+ -o accel_struct.vtk
+.Ed
+.Sh SEE ALSO
+.Xr htrdr-atmosphere 1 ,
+.Xr atrri 5 ,
+.Xr atrtp 5 ,
+.Xr htrdr-image 5 ,
+.Xr htrdr-materials 5 ,
+.Xr htrdr-obj 5 ,
+.Xr smsh 5
+.Rs
+.%A Morgan Sans
+.%A Mouna El Hafi
+.%A Vincent Eymet
+.%A Vincent Forest
+.%A Richard Fournier
+.%A Najda Villefranque
+.%T Null-collision meshless Monte Carlo - A new reverse Monte Carlo \
+algorithm designed for laser-source emission in absorbing/scattering \
+inhomogeneous media
+.%J Journal of Quantitative Spectroscopy and Radiative Transfer
+.%V 271
+.%D 2021
+.%U https://doi.org/10.1016/j.jqsrt.2021.107725
+.Re
+.Rs
+.%A Jérôme Yon
+.%A Fengshan Liu
+.%A Alexandre Bescond
+.%A Chloé Caumont-Prim
+.%A Claude Rozé
+.%A François-Xavier Ouf
+.%A Alexis Coppalle
+.%T Effects of multiple scattering on radiative properties of soot \
+fractal aggregates
+.%J Journal of Quantitative Spectroscopy and Radiative Transfer
+.%V 133
+.%P 374-381
+.%D 2014
+.%U https://doi.org/10.1016/j.jqsrt.2013.08.022
+.Re
+.Sh STANDARDS
+.Rs
+.%A OpenMP Architecture Review Board
+.%D March 2002
+.%T OpenMP C and C++ Application Interface
+.%O version 2.0
+.Re
+.Pp
+.Rs
+.%A Message Passing Interface Forum
+.%D July 1997
+.%T MPI-2: Extensions to The Message-Passing Interface
+.Re
+.Sh HISTORY
+.Nm
+has been developed as part of
+.Li ANR-18-CE05-0015
+Astoria project.
