# Could anybody explain the relationship between Catalyst Live and offscreen rendering

**URL:** https://discourse.paraview.org/t/could-anybody-explain-the-relationship-between-catalyst-live-and-offscreen-rendering/7975
**Category:** In Situ Support
**Created:** [September 11, 2021, 8:14am UTC](https://discourse.paraview.org/t/could-anybody-explain-the-relationship-between-catalyst-live-and-offscreen-rendering/7975 "2021-09-11T08:14:19Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![lijian\_cug](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/l/838e76/32.png) [@lijian\_cug](https://discourse.paraview.org/u/lijian_cug)
#### Post date: [September 11, 2021, 8:14am UTC](https://discourse.paraview.org/t/could-anybody-explain-the-relationship-between-catalyst-live-and-offscreen-rendering/7975/1 "2021-09-11T08:14:19Z")

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Now I use off screen rendering and in-situ visualization in ParaView 5.4.1 in my Regional Earth System Simulation, in which MPI parallelization was used. I get confused about the rendering process and mpi\_abort happened. The NVIDIA Quadro GPU card is installed in my computer. So I need your help because I am green hand at using the related functions in ParaView.  
(1) I compiled ParaView with EGL and without X11 and Qt5-GUI, the necessary Catalyst files were configured well in the tutorial. When I run the executable using only 1 process, the atmosphere model runs normally, but the in-situ animation cannot come out in the screen? How should I compile Paraview with the necessary Cmake switch? I don’t understand the mechanism of off screen or headless rendering.  
(2) My computer has one Intel CPU with 8 cores and has one NVIDIA GPU card, when I run mpirun -np 8 ./regesm, can the Catalyst Live work? How can I choose the Qt5 client GUI, VTK\_USE\_OFFSCREEN, VTK\_USE\_EGL,…?  
(3) If I have a cluster with 2 node, every node was installed with one CPU having 8 core and one NVIDIA GPU card. How can I install paraview in every node? Should I install ParaView with off screen rendering (VTK\_USE\_EGL) on every node?  
I hope the expert can explain for me, this will help me!  
Thanks

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### Author: ![danlipsa](https://discourse.paraview.org/user_avatar/discourse.paraview.org/danlipsa/32/1563_2.png) [@danlipsa](https://discourse.paraview.org/u/danlipsa)
#### Post date: [September 11, 2021, 4:58pm UTC](https://discourse.paraview.org/t/could-anybody-explain-the-relationship-between-catalyst-live-and-offscreen-rendering/7975/2 "2021-09-11T16:58:52Z")

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This may help:  
[https://kitware.github.io/paraview-docs/latest/cxx/Offscreen.html](https://kitware.github.io/paraview-docs/latest/cxx/Offscreen.html)

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### Author: ![Francois\_Mazen](https://discourse.paraview.org/user_avatar/discourse.paraview.org/francois_mazen/32/6483_2.png) [@Francois\_Mazen](https://discourse.paraview.org/u/Francois_Mazen)
#### Post date: [September 13, 2021, 6:49am UTC](https://discourse.paraview.org/t/could-anybody-explain-the-relationship-between-catalyst-live-and-offscreen-rendering/7975/3 "2021-09-13T06:49:03Z")

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> [@lijian\_cug](#):
>
> (1) I compiled ParaView with EGL and without X11 and Qt5-GUI, the necessary Catalyst files were configured well in the tutorial. When I run the executable using only 1 process, the atmosphere model runs normally, but the in-situ animation cannot come out in the screen? How should I compile Paraview with the necessary Cmake switch? I don’t understand the mechanism of off screen or headless rendering.

The live visualization should be enabled. Please check the Catalyst examples in the python script for command like : ` coprocessor.DoLiveVisualization(datadescription, "localhost", 22222)`

Best