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 3D Magnets ⇒ Plasma Confinement  Simple, readily available interface (Web?)  Conceptual

– rapid design and evaluation cycle  Standard

capable of describing complex objects

– levels of detail  Future?

– further use in detailed design (diagnostics) – reusable data description (getting tired of GL)

Design of Plasma Devices  Choice

of Magnetic Configuration

– most important! – requires 1000s of hours of supercomputer time ⇒ only parts can be made interactive (Ex 2)  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  Standard

(non proprietary)  Readily available and fast on low cost hardware • no dongles!

 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),...]

 “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)

 First,

the uncoded surface

– relatively few facets required  Color

per facet

• light shading is easy

 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  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?