Transcript VRML in Plasma Physics: two applications

VRML in Plasma Physics:
two applications
Boyd Blackwell
- Plasma Research Laboratory, RSPhysSE, ANU
- partially supported by Princeton Plasma Physics
Laboratory under DOE contract xxxxxxxxx
Aims
Conceptual 3D Magnets  Plasma Confinement
 Simple, readily available interface (Web?)
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– rapid design and evaluation cycle
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Standard capable of describing complex objects
– levels of detail
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Future?
– further use in detailed design (diagnostics)
– reusable data description (getting tired of GL)
Design of Plasma Devices
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Choice of Magnetic Configuration
– most important!
– requires 1000s of hours of supercomputer time
 only parts can be made interactive (Ex 2)
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Realization of Configuration (Example 1)
– 3D placement of sets conductors
– look for
• intuition about aspects of magnetic field shape
• mechanical interference, support possibilities
References:
Design of the Wendelstein VII-X stellarator: Nuhrenberg et al.
Alternatives
GL  OpenGL
– initial work on H-1
– why use a programming language to
describe data?
 AutoCAD(PRL) / ProEngineer (Princeton)
– very detailed, but slow
– good for detailed design and
engineering phase

Advantages of VRML

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Standard (non proprietary)
Readily available and fast on low cost hardware
• no dongles!
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Viewers are cheap (free?), multiple vendors
Transfer from professional packages (to?)
Designed to be written by people/machines
– Editors/Creators not essential for this application
Documentation:
Many good books available, most on WWW
Example 1: 3D Magnet Concept
simplest interface from design codes
(C++, FORTRAN, IDL) to 3D viewer.
 Initial IDL 3D widget viewer used for
years, but

– poor navigation
– lacked depth cues
– static image almost meaningless
(presentations)
Lowest effort VRML model

require only list of [(x,y,z)(x,y,z),...]
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“cylinder” element (VRML 1) using DEF
– messy - needs orientation, bad meshing

“Extrusion” model under VRML 2
– perfect fit to requirements
Sample of VRML 2
– a sampling of “nodes” in VRML 2 (from extrusion solution)
First attempt (VRML 1, DEF)
– very clumsy, but works (see fig on 1st slide)
Ex2: Evaluation of Plasma Shape

part of plasma shape design process
– magnetic surfaces exist in plasma
– colour code “bad” and “good”
“curvature” etc on surface

use shading to provide 3D cues
 high order rendering
– varying hues ( physics)
– varying light intensity( shape)
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First, the uncoded surface
– relatively few facets required
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Color per facet
• light shading is easy
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Color per vertex
• light shading (on most systems)
– Indexed
FaceSet
See notes
in handout
coords
face
indices
colourtable
map colours
to faces
Replicate
for second
period
Gouraud colours AND shading
–7000 facets
–Bu
(theta contravariant cpt)
Level of Detail - Object Hierarchy
complexity increases on close
examination
 helps retain information about sub
parts

– LOD examples
Future Work

Add AutoCAD->VRML (3D Studio?) nodes
at the highest level of detail (LOD)
 Add switches to control lighting, LOD,
colour/vertex or facet.
Conclusions
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work in progress...
success depends if physicists find it useful
speed - gl accelerator boards look promising
beyond viewing….
– is the simple collision model useful to “test
fit”?
– is the scripting language powerful enough
to program over inadequacies?