How to use in-situ visualisation

[prudhomm]

Does Feel++ support in-situ visualisation in paraview ? and how to use it ?

/cc @Trophime

[prudhomm]

You have to follow the next steps

Requirements

• ParaView >= 4.2, with the development headers, Python, MPI and Catalyst support enabled:
  • -DPARAVIEW_USE_MPI=ON -DPARAVIEW_ENABLE_PYTHON=ON -DPARAVIEW_ENABLE_CATALYST=ON -DPARAVIEW_INSTALL_DEVELOPMENT_FILES=ON
• Feel++, built with the following option:
  • -DFEELPP_ENABLE_VTK_INSITU=ON
• If needed, add the installation directory of ParaView to the CMAKE_PREFIX_PATH environment variable.

Usage

ParaView and simulation running on the same computer:

Step 1

First, you need to prepare the execution in ParaView:

• Launch ParaView;
• Enable Catalyst: Catalyst -> Connect;
• Pause the simulation before launching it (Catalyst -> Pause Simulation). It is STRONGLY recommended to stop the execution of the simulation before launching it, notably in order to setup the ParaView pipeline you want. Otherwise, the simulation might end before you set the pipeline and thus you won't be able to visualize any data.

Step 2

Then you can launch the simulation by adding the following options:

• --exporter.format vtk: Enable VTK exporter (required);
• --exporter.vtk.insitu.enable 1: Enable In Situ Visualization;
• --exporter.vtk.insitu.pyscript insitu.py: (Optional) Specify the python script that will be used to describe the ParaView pipeline, if you want to use a pyhton script. Otherwise, a default C++ pipeline will be used.

The link with ParaView will be automatically established.

Step 3

Eventually in ParaView, you can click on the small round icon near the PVTrivialProducer1 that will appear in the pipeline browser of ParaView to extract the raw data sent from the simulation. It will appear as a new filter named Extract: PVTrivialProducer1, which contains your raw data and allows you to visualize them.

ParaView running on your local computer and simulation running on a distant computer:

The process is similar to the previous item and uses pvserver to serve data on the remote host.

Step 0 -- Required only if the distant computer is firewalled

If the remote computer has a firewall, the port ParaView will use won't be available from the outside and thus no In-Situ Visualization will be possible natively.
However, you can still make it work by using ssh tunneling capabilities. You have to take into account that all the data will be sent through ssh, thus it will be slower than TCP connection.

To do so, when connecting to the remote server, instead of using the following command:

ssh username@server

Replace it with:

ssh -L 11111:localhost:11111 username@server

The -L 11111:localhost:11111 indicates that the data going through the network port 11111 of your local workstation will be sent to port 11111 on the distant host server though the ssh connection (localhost when you will be connected to it). The 11111 is the default port used when connecting to remote servers in ParaView.

Step 1

First, we will launch pvserver on the remote host. If you want to benefit from remote rendering (i.e. the images will be generated on the remote host), you have to set the DISPLAY variable correctly before launching pvserver.
Launch pvserver and it will output a text similar to the following:

Waiting for client...
Connection URL: cs://irma-atlas:11111
Accepting connection(s): irma-atlas:11111

Step 2

Then, launch and prepare ParaView on your local computer:

• Launch ParaView;
• If you did not perform Step 0:
  • Connect to the remote pvserver using the address provided in pvserver output;
• If you performed Step 0:
  • Connect to the remote pvserver using the following address cs://localhost:11111 (or any other port you specified instead of 11111). The localhost is required as all you data will be sent through the ssh connection you previously opened;
• Enable Catalyst: Catalyst -> Connect;
• Pause the simulation before launching it (Catalyst -> Pause Simulation). It is STRONGLY recommended as explained before.

Step 3

Finally, launch the simulation using the parameters explained in the previous item.

Example: Strasbourg Mesocenter

Step 0

First connect to hpc-login with port forwarding:

ssh -L 11111:localhost:11111 hpc-login

Step 1

Load the ParaView module to make pvserver available:
module load tools/ParaView-4.2.0.feelpp
Launch pvserver on hpc-login.

Step 2

Then, launch and prepare ParaView on your local computer:

• Launch ParaView;
• Connect to the remote pvserver using the following address cs://localhost:11111;
• Enable Catalyst: Catalyst -> Connect;
• Pause the simulation before launching it (Catalyst -> Pause Simulation). It is STRONGLY recommended as explained before.

Step 3

Finally, launch the simulation using the following arguments:

--exporter.format vtk
--exporter.vtk.insitu.enable 1
--exporter.vtk.insitu.hostname hpc-login-nodeside