Electronic Visualization Laboratory University of Illinois at Chicago Tele-immersive Cranial Implant Design Chris Scharver September 12, 2001 [email protected]

Electronic Visualization Laboratory University of Illinois at Chicago

Tele-immersive Cranial Implant Design

Chris ScharverSeptember 12, 2001

[email protected]

In collaboration withRay Evenhouse, Virtual Reality

Medicine Laboratory


Cranial Prosthetics

• Images from the current process– Before image– Magnetic resonance imaging-based model– Stereo lithography model,– After image


Problem Statement

Tele-immersive tools will allow cheaper and more rapid prototyping and evaluation of cranial prosthetic implants than clay and polymer modeling techniques.


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!


Jim Foley’s Top Ten (2000)

• Top ten problems in computer graphics

• Updated list at Vision 2000

• #9 User interfaces for creativity


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


Skull Model

• Theoretically obtained from MRI data, then converted into geometry for loading into scene graph

• Manually made from the Visible Human data set


Hardware Setup

• PHANToM haptic device– 6DOF position and

rotation– 3DOF force feedback

• Tracking system

• Display device– Immersive display?– Would a monitor suffice?


PARIS

• Prototyped using the CAVE• Hands are visible

through the displayscreen throughthe use of ahalf-silveredmirror screen

• Tracking issimilar to anImmersaDesk


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


e-Touch 3D

• Open module API and building tool– NT and Solaris– OpenGL– GHOST SDK support

• CAVELib, trackd, and support for other platforms?


Defect Specification

• Outline with “connect the dots”

• Intersection testing• Performer provides the

ray casting

• Draping algorithms• Volumetric collision

detection


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


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?


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


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?


General Time Frame

• September-October– Install libraries, hook up hardware– Determine incompatibilities

• October-February– Interaction and modeling programming

• February-May– Testing, evaluation, refinement– Retesting


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.


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

Documents

Electronic Visualization Laboratory University of Illinois at Chicago Tele-immersive Cranial Implant Design Chris Scharver September 12, 2001 [email protected]