A Visualization System for Tidal Basins Kenrick Mock CS 470

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

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

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

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

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

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

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

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

Dictionary Data Structure

System Architecture

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

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

Schedule

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