1. ADVANCED VISUALIZATION OF ENGINE SIMULATION DATA USING TEXTURE SYNTHESIS AND TOPOLOGICAL ANALYSIS Guoning Chen*, Robert S. Laramee** and Eugene Zhang* 1.Oregon State University, Corvallis, Oregon, USA. {chengu, zhange}@eecs.oregonstate.edu 2.Swansea University SA2 8PP, Wales, United Kingdom. Laramee@swansea.ac.uk

2. Outline Introduction Vector field background Texture-based vector field visualization Vector field topology extraction Vector field simplification Results Conclusion and future work

3. Introduction Applications of Vector Field Analysis –Fluid dynamics, weather prediction, tsunami and hurricane study, airplane and automotive design Requirements of engine design –Ideal patterns (swirl motion / tumble motion) –What engineers expect to see –Therefore, our tasks are to develop A good visualization technique A means to remove noisy features

4. Introduction Requirement of visualization Requirement of editing

5. Vector Field Background Vector field A vector field is a function which associates a vector u time t. to each point x of a domain D at time t. We focus on time-independent vector field now (n = 2,3 here)

6. Vector Field Background, continued The topology of a vector field consists of –Fixed points Sources Sinks Saddles center –Separatrices Incoming Outgoing

7. Texture-Based Vector Field Visualization Previous work 4) Feature based Topology skeleton Topology skeleton[Helman&Hesselink] 1) 1)Direct Arrow plots, icons 2) Geometric Streamline[Jobard et al, Turk et al.] 3) Texture based Spot noise[van Wijk], Spot noise[van Wijk], LIC[Cabral&Leedom] LIC[Cabral&Leedom] UFLIC[Shen &Kao] UFLIC[Shen &Kao] AUFLIC[Liu et al.] AUFLIC[Liu et al.] DLIC [Sundquist] DLIC [Sundquist] LEA [Jobard et al.] LEA [Jobard et al.] UFAC[Weiskopf et al.] UFAC[Weiskopf et al.]

8. Texture-Based Vector Field Visualization, continued Image-Based Flow Visualization (IBFV) Image credit: van Wijk

9. Texture-Based Vector Field Visualization, continued Image Space Advection (ISA) & IBFVS

10. Vector Field Topology Extraction Fixed point extraction Poincar\’e index Jacobian

11. Vector Field Topology Extraction, continue Separatrix calculation

12. Vector Field Simplification Previous work –Non-topology based (NTB)* Smoothing vector field potential [Ying et al.] Componentwise smoothing [Alliez et al.] –Topology-based (TB) Pair cancellation [Tricoche and Scheuermann][Zhang et al.] [Chen et al.] User guided simplification - One of the NTB techniques - Component-wise smoothing

13. Vector Field Simplification, continued User-guided smoothing Before smoothing ? is computed by using mean value coordinates

14. Vector Field Simplification A planar example of user guided simplification Note that the vector field outside the smoothing region does not change!

15. Results Simulation data analysis and visualization dataset name # of polygons # of fixed points times extracting fixed points (s) time computing separatrices(s) time total(s) Gas engine105,192560.169.099.25 Diesel engine886,2962263.164.487.64 (The experiments are carried out on a PC with 3.6GHZ CPU and 3GB RAM )

16. Results, continued User guided simplification

17. Advanced Results (not included in this paper yet) Detection of recurrence in the flow –Periodic orbit extraction using Morse decomposition Guoning Chen, Konstantin Mischaikow, Robert S. Laramee, Pawel Pilarczyk, and Eugene Zhang. Vector Field Editing and Periodic Orbit Extraction Using Morse Decomposition. IEEE Transactions on Visualization and Computer Graphics, Vol. 13, No. 4, pp. 769-785, 2007

18. Conclusion and Future Work Summary –Texture-based flow visualization –Enhanced visualization using vector field analysis –User guided vector field simplification Future work –Move on to time-dependent vector field –Apply to 3D volume data sets –Vector field analysis techniques other than traditional topology –Automatic simplification –And more

19. Acknowledgement We would like to thank Christoph Garth, Konstantin Mischaikow, Juergen Schneider and Greg Turk for their valuable contributions.

20. Thank you!