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This presentation discusses the innovative visualization of complex molecular ribbon structures at interactive rates. It defines ribbon structures and addresses existing tools, highlighting their limitations, including static nature and lack of smooth transitions between secondary structure types. The talk introduces improvements through a combined boundary representation technique, leveraging dynamic tessellation, which allows ribbons to pass through Cα positions and achieve continuous transitions in structure representation. A live demonstration showcases these advancements in visualization.
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8th International Conference Information Visualisation 2004 “Visualization of Complex Molecular Ribbon Structures at Interactive Rates” Andreas Halm, Lars Offen, Dieter Fellner (TU Braunschweig)
Overview • What are ribbon structures? • Existing tools • Improvements • Representation based on Combined BReps • Dynamic Tessellation • Live Demo
Credit Ribbon Visualization results from the collaboration project BioBrowser (funded by the German Research Foundation, DFG) between the • Institute of Computer Graphics, TU Braunschweig and • Structural Biology,Ges. f. Biotechnologische Forschung (GBF), D. Heinz, G. Dieterich, J. Reichelt
Ribbon Structures • Schematic drawing of the backbone • Secondary Structure • -Helices • -Strands • Random turns • Tertiary Structure • Folding • -Sheets
Existing Tools – RasMol • Not passing through C-positions • Static, low Quality • No transition between different secondary structure types
Existing Tools – Chimera • Not passing through C-positions • Moves C-positions to match ribbons • Static Quality
Existing Tools – PyMol • Passing through C-positions • Static Quality • No transition between different secondary structures types
Improvements • Ribbons pass through C-positions • Using multi-resolution approach • Continuous transition between different secondary structure types
smooth face sharp face crease edge Combined BReps • Combination of • polygonal Boundary Representation • Catmull/Clark Subdivision Surfaces • Sharpness flag for each edge
Combined BReps • Subdivision level is controlled by • View frustum clipping – • Frame rate – • Projected size + • Curvature + • Contribution to the silhouette +
Spline Interpolation • Underlying structure of a ribbon is a B-spline curve • given: C-positions • desired: control points • done by solving a system of linear equations, derived from a decomposition into Bézier segments
Building the Ribbon Structure • The structure of an amino acid determines the quad for each C • Each quad is normal to the tangent of the B-Spline curve in C • To avoid twisted ribbons re-labeling may occur
Building the Ribbon Structure • Base mesh is generated by just joining the quads • Arrows are very easy, too • Using one base mesh smooth transition
Live Demo Demo
References • J.Richardson. The anatomy and taxonomy of protein structure. Adv. Protein Chem.,pages 167-339, 1981. • RasMol: http://www.rasmol.org • Chimera: http://www.cgl.ucsf.edu/chimera/ • PyMol: http://pymol.sourceforge.net/