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

2. System Overview Goal Why
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 contaminant or other material in a particular cell

4. Data Source Physical Model Computer 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

6. Time-Based Files Typically 2-5Mb in size
Value of each cell specified for a time period
VERTICALLY AVERAGED BOD DAYS= E-02 HOURS=
VERTICALLY AVERAGED BOD DAYS= E-02 HOURS=
VERTICALLY AVERAGED BOD DAYS= E-02 HOURS=

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. Final Product
Jumping straight to the program that was created…
VB 6.0

9. How was this created? 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

10. Dictionary Data Structure

11. System Architecture

12. Addressing Flicker
A 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

13. Prototyping
Prototyping used since the client was not sure what they wanted
Somewhat fuzzy requirements led to some difficulties in implementation
Requirements changed
Had to add zoom, graphical slider synchronized with tide
Fortunately did not require major re-design
Wrong origin for vectors
Meticulously engineered code for arrowheads was thrown out

14. Schedule

15. Conclusion
Successfully delivered a visualization system for tidal basins
I learned:
More about programming in Visual Basic, particularly with graphics
Experience working with a real product as opposed to an academic exercise
More rigorous requirements could have eliminated some trouble and re-work farther into the development process