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Tele-immersive Cranial Implant Design. Chris Scharver September 12, 2001 [email protected] In collaboration with Ray Evenhouse, Virtual Reality Medicine Laboratory. Cranial Prosthetics. Images from the current process Before image Magnetic resonance imaging-based model - PowerPoint PPT Presentation
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Electronic Visualization Laboratory University of Illinois at Chicago
Tele-immersive Cranial Implant Design
Chris ScharverSeptember 12, 2001
In collaboration withRay Evenhouse, Virtual Reality
Medicine Laboratory
Electronic Visualization Laboratory University of Illinois at Chicago
Cranial Prosthetics
• Images from the current process– Before image– Magnetic resonance imaging-based model– Stereo lithography model,– After image
Electronic Visualization Laboratory University of Illinois at Chicago
Problem Statement
Tele-immersive tools will allow cheaper and more rapid prototyping and evaluation of cranial prosthetic implants than clay and polymer modeling techniques.
Electronic Visualization Laboratory University of Illinois at Chicago
Current Surgical Method
• Magnetic resonance scan of patient• Stereo lithography model of defect• Defect sculpted with clay• Defect cast• Implant modeled with dental wax• Implant cast• Surgery and implantation
• Very expensive!
Electronic Visualization Laboratory University of Illinois at Chicago
Jim Foley’s Top Ten (2000)
• Top ten problems in computer graphics
• Updated list at Vision 2000
• #9 User interfaces for creativity
Electronic Visualization Laboratory University of Illinois at Chicago
Immersive Modeling
• CHIMP: Chapel Hill Immersive Modeling Program (UNC)– Architecture– http://www.cs.unc.edu/
~mine/chimp.html
• Samuel (Fraunhofer-Gesellschaft)– General use– http://vr.iao.fhg.de/
imodeling/samuel.en.html
Electronic Visualization Laboratory University of Illinois at Chicago
Skull Model
• Theoretically obtained from MRI data, then converted into geometry for loading into scene graph
• Manually made from the Visible Human data set
Electronic Visualization Laboratory University of Illinois at Chicago
Hardware Setup
• PHANToM haptic device– 6DOF position and
rotation– 3DOF force feedback
• Tracking system
• Display device– Immersive display?– Would a monitor suffice?
Electronic Visualization Laboratory University of Illinois at Chicago
PARIS
• Prototyped using the CAVE• Hands are visible
through the displayscreen throughthe use of ahalf-silveredmirror screen
• Tracking issimilar to anImmersaDesk
Electronic Visualization Laboratory University of Illinois at Chicago
Software
• PHANToM– GHOST API, NT driver only– Interface with trackd SDK?
• Display and scene graph– GHOST provides geometry and properties– OpenSG, Open Inventor, TGS Inventor 3.0,
Performer?
• Additional libraries– VTK, geolib, NURBS++, CAVERNsoft
Electronic Visualization Laboratory University of Illinois at Chicago
e-Touch 3D
• Open module API and building tool– NT and Solaris– OpenGL– GHOST SDK support
• CAVELib, trackd, and support for other platforms?
Electronic Visualization Laboratory University of Illinois at Chicago
Defect Specification
• Outline with “connect the dots”
• Intersection testing• Performer provides the
ray casting
• Draping algorithms• Volumetric collision
detection
Electronic Visualization Laboratory University of Illinois at Chicago
Modeling Method?
• Parametric surfaces– Non-Uniform Rational B-Splines (NURBS)– These are surfaces, not volumes
• Constructive solid geometry– Most algorithm implement only primitives– Implementation with polygons more difficult
• Metaballs– Blobby modeling– Already used for haptic clay applications
Electronic Visualization Laboratory University of Illinois at Chicago
Input from Artists
• Constraints– Implant must be separate piece– Cannot simply copy and paste the other side– Minute refinement is required
• What kinds of tools would you use?
• How would you apply 2D modeling tools to a tele-immersive environment?
Electronic Visualization Laboratory University of Illinois at Chicago
Collaborative Modeling?
• Mutual exclusions in interaction• Communication between the participants
– Likely only one haptic user– Audio conferencing
• Evaluation methods– Photographs of patient– Side by side comparisons– Overlays
• “Teacher-student” paradigm
Electronic Visualization Laboratory University of Illinois at Chicago
Thesis Concentration
• Not trying to create the ultimate modeling package!
• What aspects of tele-immersion are important to this usage?
• Is it worth using these technologies in this manner?
• What are the benefits and pitfalls?
Electronic Visualization Laboratory University of Illinois at Chicago
General Time Frame
• September-October– Install libraries, hook up hardware– Determine incompatibilities
• October-February– Interaction and modeling programming
• February-May– Testing, evaluation, refinement– Retesting
Electronic Visualization Laboratory University of Illinois at Chicago
Possible Consequences
• Patient is not required to travel hundreds of miles until the surgury is planned
• Cost of production is significantly lower than the current process
• Tangible and quantifiablecontribution of virtual realitytechnology to medicine.
Electronic Visualization Laboratory University of Illinois at Chicago
Credits
• http://www.bvis.uic.edu/VRML/Research/CranialImplants/CranialImplants01.htm
• http://www.evl.uic.edu/images/research/PARIS2.jpg
• http://www.sensable.com/
• http://www.etouch3d.org/etouch.htm