1. Electronic Visualization Laboratory University of Illinois at Chicago Tele-immersive Cranial Implant Design Chris Scharver September 12, 2001 scharver@evl.uic.edu In collaboration with Ray Evenhouse, Virtual Reality Medicine Laboratory

2. 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

3. 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.

4. 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!

5. 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

6. 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/imod eling/samuel.en.html

7. 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

8. 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?

9. Electronic Visualization Laboratory University of Illinois at Chicago PARIS Prototyped using the CAVE Hands are visible through the display screen through the use of a half-silvered mirror screen Tracking is similar to an ImmersaDesk

10. 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

11. 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?

12. 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

13. 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

14. 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?

15. 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

16. 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?

17. 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

18. 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 quantifiable contribution of virtual reality technology to medicine.

19. Electronic Visualization Laboratory University of Illinois at Chicago Credits http://www.bvis.uic.edu/VRML/Research/CranialImplants/Cr anialImplants01.htm http://www.evl.uic.edu/images/research/PARIS2.jpg http://www.sensable.com/ http://www.etouch3d.org/etouch.htm