410 likes | 426 Views
Introducing a novel representation called Span Space to expedite isosurface extraction, reducing processing time for both structured and unstructured grids. The approach includes geometric and interval search methods, lattice subdivision, implementation details, and a parallel algorithm for efficient extraction. Incorporating a Kd-tree for point organization, this course presents new techniques in isosurface extraction.
E N D
Accelerated Isosurface Extraction Approach Course: Visualization Modelling Presents Alex Levin International University Bremen International University Bremen 2006
Introduction International University Bremen 2006
Introduction New representation, called Span Space will reduce the running time to for both structured and unstructured grids. International University Bremen 2006
Span Space International University Bremen 2006
Isosurface Extraction We deal with Accelerated Isosurface Extraction Approach [remember?] International University Bremen 2006
Isosurface Extraction International University Bremen 2006
Isosurface Extraction International University Bremen 2006
Isosurface Extraction 1. 2. International University Bremen 2006
Isosurface Extraction International University Bremen 2006
Isosurface Extraction [Geometric Search Approach] International University Bremen 2006
Isosurface Extraction [Geometric Search Approach] International University Bremen 2006
Isosurface Extraction[Interval Search Approach] International University Bremen 2006
Isosurface Extraction[Span Space] • There is a better approach International University Bremen 2006
Isosurface Extraction[Span Space] International University Bremen 2006
Lattice (net) Subdivision International University Bremen 2006
Search Approach International University Bremen 2006
Searching Approach International University Bremen 2006
Searching Approach International University Bremen 2006
Searching Approach International University Bremen 2006
Searching Approach International University Bremen 2006
Searching Approach International University Bremen 2006
Searching Approach International University Bremen 2006
Searching Approach International University Bremen 2006
Searching Approach International University Bremen 2006
Implementation Details • How determine the dividing points {di}? • What happen with sparse dataset?-- avoid visiting empty lattice elements International University Bremen 2006
Implementation Details International University Bremen 2006
Implementation Details International University Bremen 2006
Implementation Details International University Bremen 2006
Implementation Details • To avoid this, we find di in such a way that the number of data points at each interval approximately the same. How to do it? International University Bremen 2006
Implementation Details • Sort all data points into a list and divide the list into L sub-lists having approximately the same lengths. • Problem!!More sub-division we have->larger number of empty lattice elements are possible. International University Bremen 2006
Implementation Details • What we do is: as we pre-process the data field and distribute the cells into the lattice, the non-empty lattice element are marked and connected with pointers. International University Bremen 2006
Parallel Algorithm Three steps: • Cell distribution phase: cells are partitioned into several sub-sets and distributed to Processing Elements [PE]. • Initialization phase: each PE build lattice, based on local data • Isosurface Extraction phase: each PE locally employs searching algorithm to extract the isosurface. International University Bremen 2006
Parallel Algorithm • Example: we have 3 Processing Elements: 0,1,2. After distribution each PE has its field of processing International University Bremen 2006
Kd –tree search • Remember Interval Method->min and max values?! • Min & Max -> maintaining two lists • May we combine 2 lists in one? Yes, using Kd-tree International University Bremen 2006
Kd-tree Introduction • A kd-tree (short for k-dimensional tree) is a space-partitioningdata structure for organizing points in a k-dimensional space International University Bremen 2006
Kd-tree Introduction • Example:point list = [(2,3), (5,4), (9,6), (4,7), (8,1), (7,2)] International University Bremen 2006
Kd-tree Introduction International University Bremen 2006
Kd-tree International University Bremen 2006
Construction of Kd-tree International University Bremen 2006
Summary • We showed that there is possibility to implement new approaches in for Extracting Span Space. International University Bremen 2006
References • Han-Wei Shen, Charles D. Hansen, Yarden Livnat, Christopher R. Johnson, Isosurfacing in Span Space with Utmost Efficiency (ISSUE); • Yarden Livnat, Han-Wei Shen, Christopher R. Johnson, A Near Optimal Isosurface Extraction Algorithm Using the Span Space • Johnson/Hnsen, The Visualization Handbook, chapter 2: Accelerated Isosurface Extraction Approaches International University Bremen 2006