1. If other displays and data are already loaded, select the Edit→Remove All Displays and Data menu item or the icon in the toolbar to clear them out.
2. Load some gridded data.
   • Open the Data Choosers.
   • In the Data Chooser tree click on the Files node.
   • Go to the grid data directory: /data/idv/grids/.
   • Select sample_eta_grid.nc
   • Press Add Source
3. Create the trajectory control
   • In the Fields panel open the 3D grid node and Derived node, scroll down the Derived node and select Grid 3D Trajectory.
   • In the Displays select Trajectory Colored By Parameter and press Create Display
   • After you click the Create Display button, a dialog will pop up to allow you to select the Color by parameter. From the dialog, expand the 3D grid node and select the temperature field and click the OK button.
4. Create the trajectory display
   • From the control window for this display, change the level to 700 hectopascals using Levels selector.
   • Click the Rectangle radio button as the trajectory intial area option, click and hold the left mouse button and drag a rectangle in the view window.
   • After selecting the level and specifying the initial area, click on the button Create Trajectory to create the display.
5. Change the trajectory time display
   • Bring up the display control window for the Trajectory display.
   • In the display control window go to the Times tab. Press Time Mode Change button.
   • For End Time choose From Animation Time
   • For Start Time choose Relative to End Time
   • Change the Offset for the start time to be -6 hours.
6. Try other levels and trajectory intial area options to further experiment with the grid trajectory display.

Unidata IDV Workshop for version 6.2u2 > Accessing and Displaying Data > Working with Gridded Data