Electronic Visualization Laboratory University of Illinois at Chicago Tele-immersive Cranial Implant...

Electronic Visualization Laboratory University of Illinois at Chicago

Tele-immersive Cranial Implant Design

Chris ScharverSeptember 12, 2001

scharver@evl.uic.edu

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