Feature Tracking & Visualization in 'Visit'
Total Page：16
File Type：pdf, Size：1020Kb
FEATURE TRACKING & VISUALIZATION IN ‘VISIT’ By NAVEEN ATMAKURI A thesis submitted to the Graduate School—New Brunswick Rutgers, The State University of New Jersey in partial fulfillment of the requirements for the degree of Master of Science Graduate Program in Electrical and Computer Engineering written under the direction of Professor Deborah Silver and approved by New Brunswick, New Jersey October 2010 ABSTRACT OF THE THESIS Feature Tracking & Visualization in VisIt by Naveen Atmakuri Thesis Director: Professor Deborah Silver The study and analysis of large experimental or simulation datasets in the field of science and engineering pose a great challenge to the scientists. These complex simulations generate data varying over a period of time. Scientists need to glean large quantities of time-varying data to understand the underlying physical phenomenon. This is where visualization tools can assist scientists in their quest for analysis and understanding of scientific data. Feature Tracking, developed at Visualization & Graphics Lab (Vizlab), Rutgers University, is one such visualization tool. Feature Tracking is an automated process to isolate and analyze certain regions or objects of interest, called ‘features’ and to highlight their underlying physical processes in time-varying 3D datasets. In this thesis, we present a methodology and documentation on how to port ‘Feature Tracking’ into VisIt. VisIt is a freely available open-source visualization software package that has a rich feature set for visualizing and analyzing data. VisIt can successfully handle massive data quantities in the range of tera-scale. The technology covered by this thesis is an improvement over the previous work that focused on Feature Tracking in VisIt. In this thesis, the emphasis is on the visualization of features by assigning a constant color to the features (or objects) that move (or change their shape) over a period of time. Our algorithm gives scientists an option to choose only the features ii of interest amongst all the extracted objects. Scientists can then focus their attention solely on those objects that could help them in understanding the underlying mechanism better. We tested our algorithm on various datasets and present the results in this thesis. iii Acknowledgement I would like to thank my advisor, Prof. Deborah Silver, for her support and encouragement while writing this thesis. Also, I would like to thank my parents and family who provided strong educational foundation and supported me in all my academic pursuits. I also acknowledge the help of VIZLAB at Rutgers. iv Table of Contents Abstract ..............................................................................................................................ii Acknowledgement ............................................................................................................iv List of Figures. ………………………………………………………………………...viii 1. An Overview of the thesis .............................................................................................1 2. Introduction to Scientific Visualization.......................................................................5 2.1 Examples of Scientific Visualization ........................................................................7 2.2 Scientific Visualization tools.....................................................................................9 2.2.1 VTK................................................................................................................10 2.1.2 AVS/Express ...................................................................................................12 2.1.3 ParaView .........................................................................................................15 2.1.4 VisIt .................................................................................................................17 3. Feature Tracking.........................................................................................................21 3.1 Feature Tracking Algorithms at Vizlab...................................................................23 3.2 Applications of Vizlab’s Feature Tracking Algorithms ..........................................29 3.3 Software Implementations of Feature Tracking Algorithms...................................31 3.3.1 AVS/Express implementation ........................................................................31 3.3.2 Distributed Feature Tracking Implementation ...............................................33 3.3.3 VisIt Implementation......................................................................................34 4. VisIt Environment.......................................................................................................36 v 4.1 High level design of VisIt ......................................................................................37 4.2 Workflow of VisIt ..................................................................................................37 4.3 Plugin types in VisIt................................................................................................44 4.4 Adding new plugins in VisIt ...................................................................................45 5. Feature Tracking & Visualization in VisIt ...............................................................50 5.1 Motivation ...............................................................................................................50 5.2 Feature Tracking & Visualization Functionalities ..................................................52 5.2.1 TrakTable based Color-coding.......................................................................52 5.2.2 Selective Feature Tracking.............................................................................54 5.2.3 Picking Objects by Mouse Click ....................................................................54 5.3 Custom Plugins........................................................................................................55 5.3.1 The Feature Extraction & Tracking group plugins .......................................56 5.3.2 The Visualization group plugins ...................................................................56 5.3.3 Auto-Generated Files ....................................................................................57 5.3.4 Newly added files..........................................................................................59 5.4 Feature Tracking & Visualization Workflow in VisIt...........................................61 5.5 Modifications to the Feature Tracking & Visualization Plugins...........................64 5.5.1 The trakTable based coloring .......................................................................65 5.5.2 Selective Feature Tracking...........................................................................71 5.5.3 Picking Objects with a mouse click .............................................................74 5.6 Technical Challenges with VisIt ............................................................................75 6. Results..........................................................................................................................79 7. Conclusion...................................................................................................................85 vi References ........................................................................................................................86 Appendix – I.....................................................................................................................89 Installation of the Feature Tracking & Visualization plugins in VisIt ..........................89 Feature Tracking & Visualization User manual............................................................90 Appendix – II .................................................................................................................100 File Formats.................................................................................................................100 Data structures in Scientific Visualization ..................................................................110 Pick Modes ..................................................................................................................113 AVS to vtk converter...................................................................................................114 2D to 3D converter ......................................................................................................117 Appendix – III................................................................................................................118 Feature Tracking related publications. .........................................................................118 vii List of figures Figure 1: Visualization of an array of number as an image……………………………….5 Figure 2: Examples of visualizations in the study of natural sciences. …………………..7 Figure 3: Visualization application in geography and ecology. ………………………….8 Figure 4: Examples of visualizations in formal sciences. ………………………………...8 Figure 5: Examples of visualizations in Applied Sciences. ………………………………9 Figure 6: An example of AVS Network. ………………………………………………..14 Figure 7: VisIt Dataflow network. ………………………………………………………20 Figure 8: The Feature Tracking on hurricane data. ……………………………………...21 Figure 9: The Feature Tracking based visualization pipeline. …………………………..24 Figure 10: The Featuring Tracking Interactions.