HIERARCHICAL TREES OF UNSTEADY SIMULATION DATASETS Marek Gayer and Pavel Slavík C omputer G raphics G roup Department of Computer Science and Engineering Faculty of Electrical Engineering of CTU in Prague Czech Republic The IASTED International Conference on APPLIED SIMULATION AND MODELLING ~ASM 2004~ June, , 2004 Rhodos, Greece

2ASM 2004 Outline of the presentation Introduction to real-time simulation and visualization of various physical phenomena's Using storage for real-time data replaying Unsteady simulation datasets Our solution overview –Stored data - Fluid simulator, Particle system –Forming UDS to Tree Structures –Features, advantages and comparison Demonstration of results Conclusion and future work

3ASM 2004 Real-time simulation and visualization of various physical phenomena's For simulation and visualization of various nature phenomena: –Water and liquids –Clouds, smoke –Fire and combustion –Special effects ACM SIGGRAPH Proceedings (see references in our paper)

4ASM 2004 Real-time simulation advantages Possibility to quickly obtain the results Possibility to get a good overview of the dynamics of the simulated process Easy manipulation of the simulated model Interactive changes to the simulated process with immediate visualization response Visualization of the results in readable and easily understandable form

5ASM 2004 Storing results for real-time replaying Used when computation is too slow for real-time simulation and visualization Results are stored on hard disk, then real-time replayed –Data sets for selected characteristics –AVI and MPEG files –Limited interaction Our concept: HIERARCHICAL TREES OF UNSTEADY SIMULATION DATASETS

6ASM 2004 Unsteady simulation datasets (UDS) Stores one or more characteristics for selected time part Can allow real-time replaying of results Full interactivity in visualization part After storing, no interactivity in simulation part No additional changes to already computed data and configuration

7ASM 2004 Example storage of data - fluid simulator Dividing boiler area to structured grid cell arrays containing: –Velocities –Masses/Pressures –O 2 concentrations –Temperatures State update Principle of local simulation

8ASM 2004 Example storage of data - particle system Used for both simulation and visualization of the combustion process Virtual particle system approach Simplified combustion and heat transfer computation

9ASM 2004 Forming UDS to tree cluster structure

10ASM 2004 Changing simulation parameters in each of the tree node

11ASM 2004 UDS tree features and advantages Incremental and step by step solution Re-playable results of the simulation Interactive addition and deleting of parts Hierarchical storage of various states Interactive change of boundary conditions in each of the nodes Constructing various paths in the tree Extending of already computed tasks

12ASM 2004 Comparison against direct simulation Can run in orders faster Seeking and skip frame ability Creating hierarchy of replay-able results Incremental step-by-step solution Interactivity is allowed only in the nodes of the tree Requires disk bandwidth and capacity Note: Please refer to our paper for more detailed comparison and samples with performance measurements and discussions

13ASM 2004 Our interactive combustion system

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16ASM 2004 Possible applications Originally used for our fluid application for combustion processes Can be reused for others simulation and visualization applications, that either use or can be extended to use unsteady datasets E.g.: simulation and animation of liquids, water and gaseous phenomena

17ASM 2004 Conclusion and future research Concept of Unsteady Datasets Tree offers: –Overcomes drawback of unsteady datasets, of loosing interactivity on the simulation side. –Incremental, step-by-step construction and replaying of simulation configurations with interactive visualization of results –Can be used in general simulation and modelling applications based on unsteady datasets Future research: –Optimal data compression and encoding methods –Testing with very large data sets –Various data Interpolation techniques

18ASM 2004 Thank you for your attention. ?????? Do you have any questions ?