2006/10/25 1 A Virtual Endoscopy System Author ： Author ： Anna Vilanova 、 Andreas K ö nig 、 Eduard Gr ö ller Source :Machine Graphics and Vision, 8(3), pp , 1999 Speaker : Cheng-Jung Wu Advisor : Ku-Yaw Chang

2006/10/25 2 outline Introduction Introduction Structure of a Structure of a Virtual Endoscopy system Optimal path calculation Optimal path calculation Conclusion Conclusion

2006/10/25 3 Introduction Virtual endoscopy Virtual endoscopy a promising new technique a promising new technique explore hollow organs and anatomical cavities explore hollow organs and anatomical cavities Application Application non-invasive diagnostic endoscopy non-invasive diagnostic endoscopy educational purposes educational purposes special parts of the human body special parts of the human body a special field of application a special field of application

2006/10/25 4 VirEn Prototype Application snapshot Enlargement of the overview

2006/10/25 5 outline Introduction Introduction Structure of a Structure of a Virtual Endoscopy system Optimal path calculation Optimal path calculation Conclusion Conclusion

2006/10/25 6 Structure of a Structure of a Virtual Endoscopy system VirEn Interactive virtual endoscopy system

2006/10/25 7 Structure of a Structure of a Virtual Endoscopy system Two main issues accuracy diagnosis and surgical planning acquisition, segmentation and rendering user interaction clinical acceptance the navigation and the rendering

2006/10/25 8 Segmentation automatization accuracy ： inversely proportional manual tedious and time-consuming semiautomatic accuracy due to user supervision being not as time consuming as a manual segmentation

2006/10/25 9 Rendering direct volume rendering directly visualize the volume data no segmentation required computationally expensive no loss of information surface rendering object of interest segmentation required a mesh of polygons not just the shape the surrounding tissue is important

2006/10/25 10 Navigation peculiarities inspect the internal part of an organ keeping the camera as close to the center of the hollow organ as possible

2006/10/25 11 Navigation module

2006/10/25 12 Optimal path generation skeleton the locus of points that are geometrically centered with respect to the object boundary

2006/10/25 13 Optimal path generation two techniques to extract a skeleton in discrete space Topological Thinning a mathematical foundation the connectivity preservation The Distance Transform Method the center of an object coincides with points having maximal distance to the borders less time consuming than the thinning operation

2006/10/25 14 Optimal path generation 1 2 3

2006/10/25 15 Camera motion Planned navigation computer animation and robot automatically calculate Smooth camera movements starting point to a target point the lack of interactivity Manual navigation control over all parameters without any constraints lost-in-space

2006/10/25 16 Camera motion Guided navigation control over the camera parameters some constraints motion too constrained ： planned navigation no constraints ： manual navigation camera metaphors viewpoint manipulation techniques a real world analogy flying, walking

2006/10/25 17 Camera motion

2006/10/25 18 outline Introduction Introduction Structure of a Structure of a Virtual Endoscopy system Optimal path calculation Optimal path calculation Conclusion Conclusion

2006/10/25 19 Optimal path calculation the prerequisites for intuitive navigation the prerequisites for intuitive navigation kept in the center of the hollow structure and connectivity is preserved kept in the center of the hollow structure and connectivity is preserved The thinning approach in VirEn the fully parallel 3D thinning algorithm

2006/10/25 20 Thinning algorithm a ： fully parallel algorithm result b ： not fully parallel algorithm result b artificial data a

2006/10/25 21 Thinning algorithm c ： plus avoiding orientation dependencies b c

2006/10/25 22 Some results using a real data set Skeleton obtained by the topological thinning together with a transparent surface of the binary segmented data.

2006/10/25 23 outline Introduction Introduction Structure of a Structure of a Virtual Endoscopy system Optimal path calculation Optimal path calculation Conclusion Conclusion

2006/10/25 24 Conclusion A basic prototype based on VirEn Special effort navigation optimal path calculation Research and implementation effort direct volume rendering navigation structures Additional work camera motion model

2006/10/25 25 The End Thanks!