VisIt

​https://wci.llnl.gov/simulation/computer-codes/visit/ Visit Home Page]

VisIt is an Open Source, interactive, scalable, visualization, animation and analysis tool. From Unix, Windows or Mac workstations, users can interactively visualize and analyze data ranging in scale from small (<10¹ core) desktop-sized projects to large (>10⁵) leadership-class computing facility simulation campaigns. Users can quickly generate visualizations, animate them through time, manipulate them with a variety of operators and mathematical expressions, and save the resulting images and animations for presentations. VisIt contains a rich set of visualization features to enable users to view a wide variety of data including scalar and vector fields defined on two- and three-dimensional (2D and 3D) structured, adaptive and unstructured meshes. Owing to its customizable plugin design, VisIt is capable of visualizing data from over 120 different scientific data formats (see this ​partial list).

Introduction

Installation

• You can download executables from ​here.
• You can download the source code and compile it. They provides a script that automatically builds VisIt with all dependent libraries.

Execution Models

Stand alone

• Basically, you install VisIt on your desktop (laptop) computer in front of you. And visualize data stored in the file system in your computer.
• If you ran simulations on Cypress, you have to download the results data to the local computer with 'scp' or 'rsync' command.

Server - Client System

• VisIt is able to visualize data stored in remote computers over the network.
• You don't have to download the data into the local computer in order to visualize it.
• For example:
  • Suppose you ran simulations on Cypress and stored results in the luster file system.
  • Run VisIt on the local computer and choose the remote file system when you open a data file.
  • VisIt program automatically runs on the remote computer and reads the data file.
  • You can work with VisIt as usual on the local computer.
• Also you can use multiple nodes to render objects in parallel, which allow you to visualize a large data set.

• You must have same major version of VisIt on both local and remote computers.
• Run "VisIt" on local machine and go to "Options" -> "Host profiles…"
  • Click [New Host] and edit like below:
  • Set Host nickname as you like.
  • Remote host name must be "cypress1.tulane.edu" or "cypress2.tulane.edu".
  • Set Path to visit installation.
    • Note that "/share/apps/visit/2.9.2" is where VisIt is installed on cypress. This may be changed in the future. Use "module avail" command to see which version is available on cypress.
    • The current version is 2.9.2 so you have to use visit 2.9.* on local machine.
  • Set Username. This is your login ID for Cypress.
  • Check on Tunnel data connection through SSH
  • Click [Apply].

Serial Rendering

This set up VisIt to render objects with one process.

• Select on [Launch Profile] tab.
  • Click [New Profile] and select [Setting] tab. Give a name on Profile name.
  • Select [Parallel] tab and check Launch parallel engine.
  • Select [Launch] tab and set srun on Parallel launch method.
  • Set Numbers of processors and nodes 1.
  • Click [Apply].

• After setup, do not forget to save : Go to "Options" -> "Save Settings".
• Once setup and saved, you don't have do this again.

Parallel Rendering

This set up VisIt to render objects with multiple processes on multiple nodes.

• Select on [Launch Profile] tab.
  • Click [New Profile] and select [Setting] tab. Give a name on Profile name.
  • Select [Parallel] tab and check Launch parallel engine.
  • Select [Launch] tab and set sbatch/mpirun on Parallel launch method.
  • Set Number of processors, this is the total processors.
  • Set Number of nodes.
    • The example below sets Number of processors is 20 and Number of nodes is 2. This will use 2 nodes and 20 processes in total; 10 processes for each node.

• Select [Advanced] tab.
  • Check Launcher arguments. This is the parameters for SLURM queuing system.
    • In the example below, requesting 64G of RAM and 10 tasks (processes) per node.
  • Check Sublauncher pre-mpi command and set module load intel-psxe/2015-update1 visit. This is important to launch MPI tasks.

• After setup, do not forget to save : Go to "Options" -> "Save Settings".
• Once setup and saved, you don't have do this again.

• To read data on cypress, "Open" and choose a Host, there must be "cypress" on the list.
• You may be asked typing password every time you read data if you haven't set up passwordless ssh login.