VisIt: A Tool for Visualizing and Analyzing Very Large Data Hank Childs, Lawrence Berkeley National Laboratory

December 13, 2010

VisIt is an open source, richly featured, turn-key application for

large data. Used by:

Visualization experts Simulation code developers Simulation code consumers

Popular R&D 100 award in 2005 Used on many of the Top500 >>>100K downloads

217 pin reactor cooling simulation Run on ¼ of Argonne BG/P

Image credit: Paul Fischer, ANL

1 billion grid points / time slice

VisIt is used to look at lots of types of simulated and

experimental data.Fusion, Sanderson, UUtah

Particle accelerators, Ruebel, LLNL

Astrophysics, Childs

Nuclear Reactors, Childs

AGU examples: environmental management

Image credit: Horsman & Bethel, LBL

AGU example: earthquakes

Image credits: Boyle, LBL

AGU example: climate

Image credit: Prabhat, LBL

Terribly Named!!!… intended for much more than just visualization

Data Exploration Presentations

VisualDebugging

Analysis

General analysis techniques (e.g. integration, volumes, surface areas, etc.)

Specialized analysis (e.g. hohlraum flux at AGEX)

Detectorat AGEX

Detectorprovided by VisIt

(synthetic diagnostic)

What sort of analysis is appropriate for VisIt?

VisIt has a rich feature set. Meshes: rectilinear, curvilinear, unstructured, point, AMR Data: scalar, vector, tensor, material, species Dimension: 1D, 2D, 3D, time varying Rendering (~15): pseudocolor, volume rendering, hedgehogs,

glyphs, mesh lines, etc… Data manipulation (~40): slicing, contouring, clipping,

thresholding, restrict to box, reflect, project, revolve, … File formats (~110) Derived quantities: >100 interoperable building blocks

+,-,*,/, gradient, mesh quality, if-then-else, and, or, not Many general features: position lights, make movie, etc Queries (~50): ways to pull out quantitative information,

debugging, comparative analysis

VisIt employs a parallelized client-server architecture.

Client-server observations: Good for remote

visualization Leverages available

resources Scales well No need to move data

Additional design considerations:

Plugins Multiple UIs: GUI (Qt),

CLI (Python), more…

remote machine

Parallel vis resources

Userdata

localhost – Linux, Windows, Mac

Graphics Hardware

You don’t have to run VisIt You don’t have to run VisIt this way! this way!

You can run all on localhost You can run all on localhost You can tunnel through ssh You can tunnel through ssh

and run all on the remote and run all on the remote machinemachine

VisIt recently demonstrated good performance at unprecedented scale.

● Weak scaling study: ~62.5M cells/core

11

#coresProblem Size

ModelMachine

8K0.5TIBM P5Purple

16K1TSunRanger

16K1TX86_64Juno

32K2TCray XT5JaguarPF

64K4TBG/PDawn

16K, 32K1T, 2TCray XT4Franklin

Two trillion cell data set, rendered in VisIt by David Pugmire on ORNL

Jaguar machine

The VisIt team focuses on making a robust, usable product for end users.

• Manuals– 300 page user manual– 200 page command line interface manual– “Getting your data into VisIt” manual

• Wiki for users (and developers)• Revision control, nightly regression

testing, etc• Executables for all major platforms• Day long class, complete with exercises

Slides from the VisIt class

VisIt is a vibrant project with many participants.

Over 75 person-years of effort Over 1.5 million lines of code Partnership between: Department of Energy’s Office

of Science, National Nuclear Security Agency, and Office of Nuclear Energy, the National Science Foundation XD centers (Longhorn XD and RDAV), and more….

2004-6

User communitygrows, includingAWE & ASC Alliance schools

Fall ‘06

VACET is funded

Spring ‘08

AWE enters repo

2003

LLNL user communitytransitioned to VisIt

2005

2005 R&D100

2007

SciDAC Outreach Center enablesPublic SW repo

2007

Saudi Aramcofunds LLNL to support VisIt

Spring ‘07

GNEP funds LLNL to support GNEP codes at Argonne

Summer‘07

Developers from LLNL, LBL, & ORNLStart dev in repo

‘07-’08

UC Davis & UUtah research done in VisIt repo

2000

Project started

‘07-’08

Partnership withCEA is developed

2008

Institutional supportleverages effort from many labs

More developersEntering repo allthe time

VisIt: What’s the Big Deal?

Everything works at scale Robust, usable tool Features that span the “power of

visualization”: Data exploration Confirmation Communication

Features for different kinds of users: Vis experts Code developers Code consumers

Healthy future: vibrant developer and user communities

“How to make VisIt work after you get home” How to get VisIt running on your machine

Downloading and installing VisIt Building VisIt from scratch

How to get VisIt to read your data Support for shapefiles, NetCDF, HDF5, and 100+

more How to get help when you run into trouble

See http://www.visitusers.org/index.php? title=SC10_Tutorial

Anatomy of a picture

Image credit: Horsman & Bethel, LBL

Satellite image externally obtained and manually registered to simulation space and elevated using height information obtained

from yet another external source.

Satellite image externally obtained and manually registered to simulation space and elevated using height information obtained

from yet another external source.

Contour of scalar field from simulation

Contour of scalar field from simulation

Custom reader to read well bore

data

Custom reader to read well bore

data

Lots of “elbow grease” to make

this picture.

Lots of “elbow grease” to make

this picture.

AGU example: climate

Image credit: Prabhat, LBL

This is basically the “out of box” picture, modulo

changes in color table and annotations.

This is basically the “out of box” picture, modulo

changes in color table and annotations.

Summary

VisIt is a richly featured visualization tool that is capable of visualizing data from many different application areas. Truth in advertising: a general interface & it sometimes

takes a lot of effort to get the visualization you want. VisIt has excellent built in support for large data sets. User resources:

Main website: http://www.llnl.gov/visit Wiki: http://www.visitusers.org Tutorial: http://www.visitusers.org/index.php?

title=SC10_Tutorial Contacts:

Hank Childs, hchilds@lbl.gov General VisIt user email list: visitusers@ornl.gov