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Colon Visualization Using Shape Preserving Flattening PowerPoint Presentation
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Colon Visualization Using Shape Preserving Flattening

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Colon Visualization Using Shape Preserving Flattening

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  1. Colon Visualization UsingShape Preserving Flattening Joseph Marino and Arie Kaufman Stony Brook University

  2. Introduction • Virtual colonoscopy is a popular non-invasive colon screening method • Various colon flattening methods proposed • Cylindrical projections of segments [Vilanova Bartoli et al.] • Mass-spring unfolding [Umemoto et al.] • Conformal mapping [Haker et al., Hong et al.] • Need methods to visualize flattened colons

  3. Related Work • Visualize conformally flattened colon meshes • Shape characteristics are of utmost importance • Polygonal rendering of flattened meshes • Use per-vertex normals of original surface mesh • Encode geometric properties as color at each vertex • E.g., curvature • These methods do not have the quality or look of the VC endoluminal view

  4. Generating 2D Views • Use volumetric ray casting • Similar to endoluminal view • Obtain view position for each ray • For each column of pixels in final image • Average original 3D positions of each pixel • These form a flattened centerline along the entire colon • Use these as view point for ray casting(each column uses its average position value)

  5. 2D Surface Views • Opaque transfer function • Typical colon surface view • Structures identifiable due to shape preserving map • This rendering is more natural to view and of higher quality than a simple mesh rendering

  6. Further 2D Views • Using ray casting also allows for other rendering effects • E.g., electronic biopsy rendering • Given two flattened colons with a one-to-one and onto correspondence, obtaining matching views in 2D is trivial

  7. Integration for 3D Navigation • Flattened colon can help guide 3D navigation • For a location on the flattened colon, obtain the view frustum to view that location in the endoluminal view • View position either on flattened centerline or volumetric skeleton

  8. Obtaining View Frustums Given: location p on the surface viewpoint o on centerline (closest to p) neighboring centerline points c0 and c1

  9. Corresponding View Frustums If one-to-one and onto mapping between two flat colons Given view frustum on supine, find corresponding view frustum in prone Similar to previous

  10. Conclusion • Methods to integrate shape preserving flattening into VC system • Flattened 2D view with same look and feel as typical 3D endoluminal view • Use 2D flattened mesh to assist in navigation in the 3D endoluminal view

  11. Acknowledgements • This work has been supported by NIH grant R01EB7530 and NSF grants IIS0916235, CCF0702699. • The datasets are provided through the NIH, courtesy of Dr. Richard Choi, Walter Reed Army Medical Center.

  12. Questions & Answers