A Visualization System for Tidal Basins

1. A Visualization System for Tidal Basins Kenrick Mock CS 470 Proposal

2. System Overview • Goal • Develop a system to graphically visualize properties of tidal basins • Client is Coastal Engineering • Why • Visualization will aid in the analysis of coastal erosion, effects of pollution, navigational access, and other aspects of waterways • To visualize the system today, Coastal Engineering uses a manual process of loading data into Excel

3. Data Files • Area of interest divided into 2D grid of cells. Five files containing source data. • Depth • Depth to basin floor, -99 to represent land • Elevation • Height of the water, indicates tide • U velocity • X velocity of water in a particular cell • V velocity • Y velocity of water in a particular cell • Concentration • Percentage of silt or other material in a particular cell

4. Data Source • Physical Model • Miniature version of the real thing • Computer Model • Fortran program • Most data in this project generated from a computer model

5. Data File Format • All files are in text • Depth file example • Mapping -99.00 -99.00 3.96 3.96 -99.00 3.96 3.96 3.96 -99.00 3.96 3.96 -99.0

6. Time-Based Files • Typically 2-5Mb in size • Value of each cell specified for a time period VERTICALLY AVERAGED BOD DAYS= 2.0833334E-02 HOURS= 0.5000000 -2.00 -2.00 1.00 1.00 -2.00 1.00 1.00 1.00 -2.00 1.00 1.00 -2.00 VERTICALLY AVERAGED BOD DAYS= 4.1666668E-02 HOURS= 1.000000 -2.00 -2.00 0.98 0.94 -2.00 0.98 0.95 0.93 -2.00 0.97 0.94 -2.00 VERTICALLY AVERAGED BOD DAYS= 4.1666668E-02 HOURS= 1.500000 -2.00 -2.00 0.94 0.92 -2.00 0.95 0.93 0.91 -2.00 0.94 0.87 -2.00

7. Visualization Using Excel • Import data, assign colors based on values • Slow! • Especially slow for time-based data • Solution: Program to automatically visualize data

8. Specifications • Dialog box to select data set • Graphical display corresponding to the data in the tidal basin • “Play” button to animate display for each time step • A “play” button should be placed on the application that begins animating the graphical display for each time step. • Concentration and Elevation should be displayed in different cell colors, with at least three levels of greyscale required and colors optional • Display quantity E, essentially the inverse of concentration • Velocity vector should be drawn in each cell specifying direction of velocity

9. Mock-up of Proposed Solution Will use prototyping to incrementally refine the system

10. System Specifications • Windows 2000 or XP • Visual Basic 6.0 • 256 Mb of memory, 450Mhz or higher • 1024 by 768 pixel resolution

11. System Design • For speed, load all data into memory • Depth file: 2D array • Time-based files: • Dictionary of 2D arrays • Simpler than a 3D array • Dictionary is like a dynamic, content-based vector

12. Dictionary Data Structure

13. System Architecture

14. Addressing Flicker • Screen update while cells are being re-drawn for the next time step can result in unpleasant flicker • Use “Double Buffering” solution • Draw new cell colors on the hidden screen • Draw new vectors for velocities on the hidden screen • Copy entire hidden screen to the visible screen

15. Planning Estimated 156 hours total with incremental prototyping methodology: Requirements: 15.6 hours Design: 15.6 hours Implementation: 43.7 hours Testing: 49.9 hours Write-up: 15.6 hours Presentation: 15.6 hours

16. Schedule

17. Conclusion • Goal is the delivery of a system to visualize tidal basins • Many challenges • Refining the design and specifications • Lack of formal specifications is expected to lead to future specifications and requirements • Prototyping methodology • Proposed solution • Utilize Visual Basic’s dictionary object, event processing, and easy UI design to construct a usable and powerful system