Atmosphere Starter Pack

The htrdr: Atmosphere Starter Pack contains input data to perform renderings with htrdr-atmosphere. It also provides shell scripts that run predefined htrdr-atmosphere commands. These scripts are examples and good starting points for learning how to run htrdr-atmosphere; users are encouraged to modify and extend them.

Content

Images of the DZVAR, DZVAR2, L12km_BOMEX and L25_Fire scenes rendered with htrdr-atmosphere.

Atmospheric profile

The ecrad_opt_prop.txt file defines the gas optical properties provided for the pressure and temperature atmospheric vertical profile. These data were generated with the ECRAD software and are saved according to the htgop file format.

Clouds

The files contained in the clouds subdirectory contains htcp files defining the liquid water content in suspension within clouds. These fields are generated from idealized Large Eddy Simulations computed by the French non hydrostatic research model, MesoNH (Lafore et al. 1998, Lac et al. 2018), with flat surfaces and prescribed large-scale forcings. Available files are:

• DZVAR.1.ARMCU.008.diaKCL.htcp: a continental cumulus case initialized from a composite of observed thermodynamic profiles measured on the ARM SGP site, following Brown et al. (2002). The provided field corresponds to the 8th hour of simulation (13h30 local time), in the middle of the diurnal cycle. The boundary layer is well-developed with cloud base height around 1km and cloud top around 2km, and a total cloud cover of around 25% of the 6.4km x 6.4km domain (horizontal resolution is 25m).
• L12km.1.BOMEX.005.htcp: an oceanic, trade wind cumulus case initialized from observed thermodynamic profiles acquired during the BOMEX campaign in the Barbados. The model set-up is as in Siebesma et al. (2003) but with a 12.8km x 12.8km domain and resolution 25m. The cloud layer is between 500m and 1.5km heights and covers around 14% of the domain.
• L25.1.FIRE.012.htcp: a marine stratocumulus case initialized from observed thermodynamic profiles acquired during the FIRE campaign off the coast of southern California. The model set-up is as in Duynkerke et al. (2004) with a 25km x 25km domain, 100m horizontal and 10m vertical resolutions. The field corresponds to the 12th hour of simulation (12h local time) typical of a decoupled boundary layer, with the overcast stratocumulus layer between 300 and 600m.

Water droplets properties

The Mie_LUT_Cloud-2-10-0.010.nc file stores the spectro-angular tabulation of water droplets optical properties computed using the Mishchenko et al. (2002) implementation of the Lorenz-Mie solution for light scattering by homogeneous spherical particles The monodisperse solution was integrated over a log-normal droplet size distribution of effective radius 10 micrometers and effective variance 0.01 micrometers. This NetCDF file is formatted according to the htmie file format.

The image of the city scene rendered with htrdr-atmosphere. The thin lens camera used in this rendering focuses on background elements; the foreground vegetation is out of focus.

Geometries

The models subdirectory contains geometries saved in the htrdr-obj file format. Available geometries are:

• models/city.obj: geometry of 19,517,682 triangles of a procedurally generated city using several materials.
• models/desert.obj: OBJ of 2,097,152 triangles representing a desert. The geometry starts from 0 and extends to 10 kilometers in both X and Y dimensions. The maximum dune height is 100 meters. The geometry is cylic and thus can be infinitly repeated along the X and Y dimension.
• models/mountain.obj: geometry of 8,388,608 triangles representing mountains. The OBJ lower bound is 0 while its upper bound is [10000, 10000, 700] which means that its size along the X and Y axis is 10 kilometers while the highest mountain peaks at 700 meters. Note that the geometry is carefully designed to be cyclic: it can be repeated along the X and Y axis without visual glitches.
• models/plane.obj: quad centered in 0 whose size along the X and Y dimension is 10 meters.
• models/sea_3m.obj: geometry of 8,388,608 triangles representing a sea starting from 0 and extending to 10 km along the X and Y axis. The maximum wave height is 3 meters. The geometry is cyclic, that means that it can be repeated along the X and Y dimensions.

Image of the DZVAR cloud field rendered from the top of the atmosphere with an orthographic camera.

Ground materials

The materials/legacy subdirectory regroups various MruMtl files representing materials whose spectral properties have been collected / inferred from available public sources: handbooks, manufacturer web sites, and public databases such as the USGS High Resolution Spectral Library. Various sources have most of the time been necessary in order to gather data over the whole thermal infrared range.

The MruMtl files contained in the materials/slum subdirectory are generated from the Spectral Library of impervious Urban Materials (SLUM) developped by S. Kotthaus et al.

Finally, a set of htrdr-materials are stored in the materials directory. Each file is a list materials required by the ground geometries (city.mtls, desert.mtls, mountain.mtls, plane.mtls, sea.mtls), or the whole set of materials contained in the aforementionned sub-directories (legacy.mtls and slum.mtls files).

Shell scripts

The provided shell scripts runs a htrdr-atmosphere command without any frills except command arguments that are described by variables for ease of reading. This is to give examples to users and invite them to study and modify these commands according to their needs.

Install and run

Download the Atmosphere Starter-Pack archive and verify its integrity against its PGP signature. Then extract it.

Assuming htrdr-atmosphere is properly installed and registered on your current shell, just run the desired script. For example, to render the city scene:

./city.sh

When invoking the script, htrdr-atmosphere is executed according to the data and parameters defined in the city.sh file. After calculation, the resulting image city_1280x720x256.txt is stored as htrdr-image file format. One can then use the program htpp to convert it into a normal PPM file which can then be displayed with a regular Image viewer.

htpp -i exposure=0.2 -o city.ppm city_1280x720x256.txt

Donwloads

Version 0.8

The GNU Bash htrdr-run.sh, a script used to dynamically construct an htrdr-atmosphere command line, is now replaced by a set of POSIX shell scripts, each executing a predefined htrdr-atmosphere command, without frills. Their only refinement is that command-line arguments are defined using variables for ease of reading. In addition to its extensive compatibility, this rewrite was done to simplify the reading and study of scripts in order to encourage users to edit and extend them.

Version 0.7

• Add the city_thin_lens scene. It sets a rendering of the city scene with a thin lens camera.
• Add the L12km_BOMEX_desc_flux_sw scene used to compute the downward shortwave flux under the BOMEX cloud field.
• Add the DZVAR_ortho scene. It defines an orthographic rendering of the DZVAR cloud field from the top of the atmosphere.
• Add the support of the sensor_type keyword in the scene files. Available types are: perspective camera, orthographic camera and flux map.
• Remove the support of the operf keyword in the scene files.
• Rename the ht-run.sh script in htrdr-run.sh.

Version 0.6.1

• Update the ht-run.sh script to handle the command update introduced by htrdr 0.7.

Version 0.6

• Add the desert.obj and sea_3m.obj geometries and their associated desert.mtls and sea.mtls htrdr-materials file.
• Update the "ground" geometry of the DZVAR2 and L12km_BOMEX scenes: use the desert rather than a plane in DZVAR2 and replace the mountains by a sea in L12km_BOMEX.
• Make specular the blue_water legacy material.

Version 0.5

• Add new materials generated from the Spectral Library of impervious Ubran Materials (SLUM).
• Define one htrdr-materials file for each ground geometry.
• Update the htrdr-materials files with respect to the fileformat updates introduced by htrdr 0.6.
• Update the city.obj file. This new geometry fix the interface description, use detailed tree meshes and the new SLUM materials.

Version 0.4

• Add the longwave and shortwave scene variables that enable the longwave or shortwave spectral integration onto the defined wavelength range with respect to the Planck function for a given reference temperature. This reference temperature can be set through the reference_temperature variable.
• Update the Mie lookup table: in the previous one, the effective mass was no correctly computed.
• When MPI is enabled, force the path of the output image to the $HOME/.htrdr local directory of the first host listed in the mpi_hosts scene variable.
• remove the long_waves keyword: it is now replaced by longwave.

Version 0.3

• Update the geometry files to make them compatible with htrdr 0.4.
• Add the city.obj geometry that stores a procedurally generated city.
• Add the long_waves variable to the scene description that enables infrared rendering and defines the range of long waves to take into account.
• Add a list of legacy materials used by the ground geometries.
• Add the materials variable to the scene description that defines the path toward the htrdr-materials file used by the scene.
• Update the layout of the .htrdr directory used when htrdr is ran through MPI. This directory, created at the root directory of each host that shared the computation, saves the input data required by the rendering as well as temporary files. For input files, this directory now strictly follows the layout of the Starter-Pack.
• Handle spaces in paths.

Version 0.2

• Update the files describing the scenes as well as the ht-run.sh script according to the updates introduce by htrdr 0.3: remove the cache_grids variable and replace it by the cache_sky one that defines whether the sky data structures are cached or not.

Copyright notice

Copyright © 2018, 2020, 2021, 2023 |Méso|Star> (contact@meso-star.com)
Copyright © 2018 Centre National de la Recherche Scientifique
Copyright © 2018 Université Paul Sabatier

The MruMtl files contained in the materials/slum subdirectory are created from the the Spectral Library of impervious Urban Materials, copyright © 2013 University of Reading.

License

htrdr: Atmosphere Starter Pack is released under the GPLv3+ license: GNU GPL version 3 or later. You can freely study, modify or extend it. You are also welcome to redistribute it under certain conditions; refer to the license for details.