Volume Graphics and the Internet

1
Volume Graphics and the Internet

• Ken Brodlie and Jason Wood
• School of Computer Studies
• University of Leeds

2
Internet

• The Internet brings connectivity
• Connectivity means
• humans can collaborate
• systems can collaborate

3
Why Collaborative Visualization?

• Visualization IS a collaborative activity!
• Scientific research is carried out in
  multi-disciplinary teams
• each person brings individual skills
• teams may be geographically distributed
• Influence of the Internet and Web
• collaborative culture
• BUT existing visualization systems
• single user model and pre-Web

4
How Can We Collaborate?

• General application sharing
• one host acts as master, broadcasts screen
  display to other participants
• collaboration at the operating system level
• SharedX, MS NetMeeting
• high bandwidth requirement
• Collaborative visualization systems
• use knowledge of application to get a better
  solution

5
Collaborative Visualization - Outline of First
Part of Talk

• Influences
• other work on collaborative visualization
• Concept
• linked dataflow
• Realisation
• IRIS Explorer COVISA toolkit
• Application
• collaboration in volume visualization

6
Tempus Fugit - Sharing Geometry

• CFD visualization system developed by Michael
  Gerald-Yamasaki at NASA Ames - Eurographics 93

workstation
Simulation Visualization
Rendering
Geometry list
supercomputer
7
ONERA - Sharing Control

• In the EU PAGEIN project, Michel Grave at ONERA
  developed a shared interface approach
• Parameters to be shared extracted into a shared
  interface above the visualization system

8
CSpray - Collaboration Issues

• Extension of Alex Pangs Spray rendering
• Particles fired into data with specific objective
  - eg locate isosurface
• In CSpray, each person has a spray can
• Careful study of issues
• floor control
• privacy
• audit trail

9
COVISA Research Objective

• Our aim was to evolve a collaborative extension
  of Modular Visualization Environments
• IRIS Explorer, AVS, IBM Data Explorer, Khoros
• usability keep same metaphor
• sharing share data and control with other
  participants
• flexibility program the collaboration to allow
  network efficiency, privacy, join-at-any-time

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We have this...
11
we want this
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Back to the Visualization Reference Model

• To design a collaborative visualization system,
  we return to the underlying Haber-McNabb
  reference model - and think how to extend it

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Collaborative Dataflow Model
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Collaborative Dataflow Modules
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Use My Network...
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See What I Can See...
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See What You Can See...
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Do Your Own Thing...
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Can I Use Your Expertise?
INPUT DATA
FILTER
RENDER
MAP
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IRIS Explorer COVISA Toolkit

• This research is now available as the COVISA
  add-in to IRIS Explorer
• Advisor, ShareParam, ShareData modules...
• ...wired in to networks exactly like any other
• See IRIS Explorer Centre Web Site
• http//www.scs.leeds.ac.uk/iecoe

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COVISA Architecture
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Starting a Session

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New Modules
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Advisor Module
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Collaborative Modules

• Modules can be written as directly collaborative
• for example, MSharePointer

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Collaborative Applications

• End-user applications can be built as a layer on
  top of a dataflow network
• selected parameters exposed to users in a simple
  interface
• collaboration can be included in these

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Application

• Video will show application to volume
  visualization
• Radiologist studying abdominal aortic aneurysm..
• collaborates with a medical physicist with
  segmentation skills

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The Story Begins With...
29
Web-based Visualization
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Visualization and the World Wide Web

• Early use for descriptive visualization
• visualize using conventional software such as
  MVEs
• publish as an image, or as 3D VRML model
• Now used also for analytical or exploratory
  visualization
• visualization process executed as a Web-based
  application
• Web-based visualization has become an established
  branch of discipline

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How Did It Start?

• Pioneering work by Ang et al 1994
• medical volume visualization system VIS used as a
  client-side application linked to Mosaic browser
• invoked on receipt of MIME-type hdf/volume
• Server-side example from Wood 1995
• air quality visualization service
• IRIS Explorer on server, returning VRML
• Now many styles of web-based visualization
• some client-based, some server-based

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Client-based Systems

• Action is at the client
• Three flavours according to what is sent from the
  Web server
• raw data
• script to drive software
• software

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Sending data - Vis5D

• Vis5D for meteorological visualization, from
  Hibbard at Wisconsin
• Configured as helper application, invoked on
  receipt of MIME-type application/vis5d
• Daily weather forecasts

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Sending a Script Client-Explorer

• Client-based system with IRIS Explorer developed
  by Alan Yeo and Jason Wood at Leeds
• Set of instructions downloaded from server to
  program IRIS Explorer on the client
• Instruction file invokes application which drives
  IE

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Sending Software VizWiz

• VizWiz is Java applet for volume visualization,
  from Michaels Bailey at SDSC
• Data is a problem must be uploaded from client
  to server to work around Java security issues

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Server-based Systems

• Action is at the server
• Three flavours according to what is sent from the
  server
• 3D graphics
• 3D graphics plus software
• images / video

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Sending VRML Air Quality Visualization Service

• Air quality web-based visualization system with
  IRIS Explorer on server, developed by Jason Wood
• User completes form saying what data, and what
  technique
• CGI script invokes IRIS Explorer
• VRML returned

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Sending VRML and Java Isosurfacing

• Engel and colleagues at Erlangen have implemented
  their progressive isosurface algorithm as a
  web-based system

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Sending VRML and JavaVolume Rendering

• Texture-based volume rendering can be delivered
  as VRML
• This VRML volume rendering developed by Nigel
  John and colleagues at SGI Biomedical
• Java applet provides interaction

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Sending Images/Video Volume Render

• Rather than render on the client, it is possible
  to render on a server and ship the images to the
  client
• this approach has been used by Stredney et al
  at Ohio for remote volume rendering
• Client uploads data to server (with 3D texture
  hardware)

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Review

• Client-based
• high interactivity
• needs software availability at client, plus skill
  to use it
• needs compute power at client but this is
  dedicated

• Server-based
• low degree of control
• software provided by server
• compute power provided by server but shared
  between many

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Extending to Collaborative Web-based Visualization

• Both client and server based systems can be
  extended to collaborative style of working -
  although surprisingly little work has been done
  in this area

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Client-based Systems

• FASTexpeditions can run in a pilot-passenger mode
• ClientExplorer can be extended to incorporate the
  COVISA shared modules
• VisAD has been used in a collaborative setting,
  with NCSA Habanero

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Server-based Systems

• Air quality visualization service (IRIS Explorer
  on server) has been extended to support
  asynchronous collaboration

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Collaborative Web-based Visualization

• Future direction could be combination of
  synchronous collaboration provided by the
  extensions of MVEs described earlier
• and the asynchronous collaboration for which the
  Web is well suited, providing a sustainable
  environment for collaboration

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Reference Model - The Processes
Setup
Base Software
Render
Design
Input Data
Script
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Client-based Systems

• Design executed on client-side

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Vis5D

• All components except the data are resident on
  the client, and executed on the client

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FAST Expedition

• FAST CFD visualization system from NASA Ames
• Setup and script can be downloaded from server -
  so a guided tour is possible

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FAST Expedition

• Distinguished from Vis5D because system SetUp
  and Script driven from server
• Client can take over the driving - hence Script
  is Client or Server based

SetUp
S
Base Software
C
Design
Render
C
C
Data
S
C S
Script
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Client-Explorer

• Distinctive in that SetUp and Script can be
  either client or server driven
• Potential application for
• education
• bureau services

C S
C
C
C
S
C S
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Java Applet Approach

• Key feature is base software on server, but
  execution on client

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VisAD

• VisAD is novel Java based system from Hibbard at
  Wisconsin
• Idea of linked objects - data objects linked to
  user interface objects etc
• Objects are Java classes that can reside at any
  URL

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VisAD

• Software can be resident either on client, or a
  remote server

C
C S
C
C
C
C
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Server-based VRML Approach

• Server-side execution, with client-side rendering
• Setup determined by client