This is the backend component of the Cube Analysis and Rendering Tool for Astronomy, a web-based application for viewing radio astronomy images in CASA, FITS, MIRIAD, and HDF51 formats.
Rather than rendering each image and sending it to the frontend client (which is the conventional approach), the backend sends a compressed subset of the data, and the frontend renders the image efficiently on the GPU using WebGL and GLSL shaders.
Although the data is compressed with the lossy ZFP algorithm, the compression artefacts are generally much less noticeable than those produced by full-colour JPEG compression.
While data sizes depend on compression quality, sizes are comparable with sizes of compressed JPEG images with a 95% quality setting (depending on the colour map used to generate the JPEG image). PNG compression is generally a factor of 2 larger than the ZFP-compressed data.
1 using the custom IDIA schema.
If you are looking for releases of the CARTA application for desktop users, please refer to the main website.
If you would like to set up CARTA in a multi-user environment, we recommend installing the CARTA controller. We provide detailed instructions for a complete deployment of all components on supported platforms.
The rest of this document describes installation of the backend component only (for use with a separately installed frontend, or with the controller).
We provide packages of the backend and all required dependencies for recent Ubuntu LTS releases and recent AlmaLinux releases. They should also work on equivalent distributions closely based on Ubuntu and on RHEL.
The packages install a launcher which allows CARTA to be started from the desktop environment's menu.
The beta package saves user configuration to .carta-beta rather than .carta.
sudo add-apt-repository ppa:cartavis-team/carta
sudo apt-get update
# install the latest beta version of the backend only
sudo apt-get install carta-backend-beta
# OR install the latest stable release version of the backend only
sudo apt-get install carta-backendThe beta and stable Ubuntu packages use the same install locations, and only one can be installed at a time.
sudo dnf install epel-release
sudo dnf install 'dnf-command(copr)'
sudo dnf copr enable cartavis/carta
# install the latest beta version of the backend only
sudo dnf install carta-backend-beta
# install the latest stable release version of the backend only
sudo dnf install carta-backendThe RPM beta package uses a custom install location in /opt, and can be installed in parallel with the stable package.
This repository includes several dependencies as submodules:
- The protocol buffer definitions for communication between the backend and frontend.
- cxxopts for parsing commandline options
- nlohmann/json for parsing JSON
- pugixml for parsing XML
- spdlog for logging
- sse2neon for ARM support
Two submodules are not required for building the main source:
- image-generator for creating FITS images (from the unit tests; soon to be deprecated)
- Doxygen Awesome, a Doxygen stylesheet (for generating the developer documentation)
You can fetch the submodule contents when you clone the repository:
git clone --recurse-submodules https://github.com/CARTAvis/carta-backend.git
cd carta-backendAlternatively, you can update them after cloning:
git clone https://github.com/CARTAvis/carta-backend.git
cd carta-backend
git submodule update --init --recursiveIf you use git pull to update an existing checkout of this repository, make sure that you also use git submodule update to fetch the appropriate versions of the submodule code.
The backend build depends on the following libraries (this is not an exhaustive list):
- casacore + casa imageanalysis. We maintain a custom version of this library.
- zfp for data compression. The same library is used on the client, after being compiled to WebAssembly.1
- Zstd for data compression.
- protobuf for client-side communication using specific message formats.
- HDF5 C++ library for HDF5 support.
- libuuid for generating auth tokens (if not using external authentication).
- cfitsio library for I/O with FITS format data files.
- wcslib library to handle world coordinate system.
We recommend using our Dockerfiles as a guideline for installing these dependencies on RPM-based and Debian-based distributions. We provide packaged versions of dependencies missing from officially supported distributions.
We use cmake to configure the build.
mkdir build
cd build
cmake ..
make -j8The packages provide a carta script which wraps the carta_backend executable. Both are available on the path. In the source build, the carta_backend executable can be found in the build directory.
Command-line arguments are in the format --arg=value or --arg value. By default, the backend will attempt to host frontend files from ../share/carta/frontend (relative to the executable path). This can be changed with the --frontend_folder argument. Run carta_backend --help for a full list of options.
Most options can also be set permanently in a user configuration file (~/.carta/backend.json, or ~/.carta-beta/backend.json for our beta packages) or a global configuration file (/etc/carta/backend.json). For example:
{
"$schema": "https://cartavis.github.io/schemas/preference_backend_schema_2.json",
"verbosity": 5,
"exit_timeout" : 0
}Automatically generated Doxygen documentation can be found at cartavis.org/carta-backend.
