TREMBLE user manual

Next: 7 Troubleshooting Previous: 5 Recording A Storm

6 Viewing a Storm

Crossbow, TREMBLE's visualization program, lets you maneuver in the local area surrounding your recording station and explore a thunderstorm's lightning strikes from any viewpoints you desire. To start Crossbow, simply run the Crossbow executable file you extracted during setup.

Crossbow with controls labeled
Figure 7. Controls and features in Crossbow lightning viewer; the image in the viewer's main window is an overhead view of Chapel Hill and Durham from the southwest.


snapshot of menu
Figure 8. Crossbow's main menu and menu options.

The main menu options are:

  • Options: Pops up a option dialog box which includes controls of storm playback speed.
  • Open Remote: Opens a storm file (*.stm) that is currently on your data server.
  • Acquire Realtime: Opens a connection to your data server and retrieves the storm data currently being output by your acquisition and analysis servers.
  • Disconnect: Terminates connection to your data server.
  • Open Local: Opens a storm file on your local machine.
  • Save Local: Saves the currently loaded storm file to your local machine.
  • Close: Closes the currently loaded storm file.
  • Quit: Exits Crossbow.

Playback Controls

snapshot of playback controls
Figure 9. Crossbow's storm playback controls featuring a VCR-like interface.

The individual playback controls are:

Display Controls

The display options and viewing options Crossbow makes available to you allow you to choose what is important for you to see.

  • terrain: This check box toggles whether Crossbow displays the terrain (topological data).
  • roads: This check box toggles the display of roads on and off.
  • buildings: This check box toggles on/off the display of buildings and their labels.
  • radar: This check box toggles whether radar information is diaplyed in Crossbow's navigation window.

  • autocam: This check box enables (or disables) the AutoCam feature, which controls navigation so that you are automatically transported to a close-up view of each lightning bolt in the storm file.
  • wireframe: This check box toggles the display of terrain in wireframe. Note that the display runs faster when wireframe mode is turned off.
  • z scale: This slider controls z-scale exaggeration, which allows you to emphasize the differences in elevation of the surrounding landscape.
  • colors: Use this drop box to choose the colors used to display different elevations of terrain in non-wireframe mode. Currently six color schemes are available: (1) green-blue, (2) white-black, (3) earthy tones (shades of brown), (4) green-purple, (5)red-black, and (6) "Go Heels!" (white-powder blue)
snapshot of display controls
Figure 10. Crossbow's display controls.

Navigation Controls

snapshot of navigation controls
Figure 11. Crossbow's navigation controls.

Crossbow's navigation controls allow you to finely control your viewpoint for viewing lightning strikes. There are six ways to change your viewpoint, each described below.

  • forward/backward: Move your viewpoint forward/backward in the direction you are currently looking.
  • pan left/right: Move your viewpoint left/right perpendicularly from the direction you are currently looking.
  • height: Change the elevation of your viewpoint by moving it up/down.
  • tilt: Tilt your viewing direction up and down. It's "backwards," just like a flight stick: to look down, press the up button ; to look up, press the down button .
  • speed: Change the speed at which you travel through the world by moving the slider left (slower) or right (faster).
  • center: Reset your viewpoint to the center of your mapping area.

In addition, there is the navigation window which shows your current viewing location. The navigation window is always the topmost window while Crossbow is running. Your current viewpoint is indicated by a red dot, your view direction or view frustum (in autocam mode) is indicated with a green line or green "V", and the position of the next lightning bolt is indicated by a yellow dot.

snapshot of Crossbow snapshot of Crossbow
Figure 12. More Crossbow screen shots. (a) shows an overhead shot of Chapel Hill with buildings labeled. (b) shows a lightning strike near the recording station viewed from about seven miles away. Click on either picture to see a larger version.
Next: 7 Troubleshooting Previous: 5 Recording A Storm

author(s): Eric D. Baker
last update: 04 May 1999 5:32p by Eric D. Baker