Project 1: Visualization and Flow Modeling on Grid Terrains

The goal of this project is to create a tool for visualization and basic flow modeling of grid datasets. The required functionality is to visualize a grid dataset in 3D and compute flow direction and flow accumulation of a grid dataset.

Visualization: The visualization routine should allow for a grid to be displayed in 3D with an appropriate perspective projection and initial viewpoint. Below are examples of some of the sample datasets in /home/toma/geodata/DEM/ directory displayed in 3D.


Additionally, if invoked with a second grid as argument, the visualization routine should display the second grid (the color grid) draped on top of the first grid (the surface grid). This functionality is useful for viewing terrain attributes like flow direction and flow accumulation draped on top of the elevation. Here is an example of flow accumulation of a terrain drawn on top of the elevation:


The visualization routine should have the following features:
• Translations and rotations: Allow for rotations and translations around the axes of both the camera and the terrain. Ideally the camera movements would be mapped onto the arrow keys so that flying through the terrain is easy to do.
• Resolution: In order to handle larger grids fast provide the option to increase and decrease grid resolution for visualization. Set the the initial resolution such that the initial rendering is always fast.
• Color maps: Implement at least two color maps and allow the user to chose between them. Here is an example of rendering an elevation grid in 2D with various color tables:

  

• Menu: Include a menu that allows to:
  • toggle between drawing the polygons in the scene filled or contour only
  • select a color map
  • quit
• Scaling: Allow for the terrain to grow/shrink on the z-axis.
• Animation: Include a simple animation of the terrain. For instance, a rotation around one of the axis. Ideally all other features (translation/rotations/resolution, scaling) will be available during the animation.
• Flow direction (FD): The FD routine should take as input an elevation grid and compute SFD or all cells in the grid which have downslope neighbors. SFD means that FD points to the stepeest downslope neighbor; if there is more than one stepeest downslope neighbor pick one (at random). If all neighbors of a cell have same height or are upslope assign FD=0.
  
• Flow accumulation (FA): The FA routine should take as input a direction grid and compute a FA grid. Assume that initially every cell in the terrain has 1 unit of water, and that every cell distributes its water (initial, as well as incoming), to the neighbor pointed to by its flow direction.
  

The interface is open-ended, but ideally the user would be able to perform any combination of these commands on any grid dataset. For instance:

lynx20: > flow
..Starting flow program.
flow> help
..Usage:
display surf=<grid-name> [col=<grid-name>]
computeFD elev=< grid-name> dir=<grid-name>
computeFA dir=< grid-name> accu=<grid-name>
help
exit
flow> display
..usage: display surf=<grid-name> [col=<grid-name>]
flow> display surf=set1.asc
..Displaying set1.asc
flow> display surf=kaweah.asc
..Displaying kaweah.asc
flow> computeFD elev=kaweah.asc dir=kaweahFD.asc
..Computing FD for kaweah.asc
flow> display surf=kaweahFD.asc
..Displaying kaweahFD.asc
flow> display surf=kaweah.asc col=kaweahFD.asc
..Displaying kaweahFD.asc draped over kaweah.asc
flow> computeFA dir=kaweahFD.asc accu=kaweahFA.asc
...Computing FA for kaweah.asc
flow> display surf=kaweah.asc col=kaweahFA.asc
..Displaying kaweahFA.asc draped over kaweah.asc
flow> display surf=kaweahFD.asc col=kaweah.asc
..Displaying kaweah.asc draped over kaweahFD.asc
flow> display surf=sierra.asc
..Displaying sierra.asc
flow> exit
..Exiting. Bye.
lynx20: