The 3D Viewer allows the user to specify a flight path polyline in RAS Mapper for the viewer to follow like a train on tracks
To lay out a flight path, first open RAS Mapper. To open RAS Mapper, on the main RAS window select the GIS Tools | RAS Mapper menu item or by pressing the 
RAS Mapper button, shown below.
Figure 8 16. HEC-RAS Main Window with HEC-RAS Mapper Button Highlighted.
A flight path layer will be needed to lay out flight paths. To do that right click on Features Group in the tree view, and then select Create New Layer | Flightpath Layer
Figure 8 17. HEC-RAS Mapper Menu with Flightpath Layer Selection shown.
Then lay out the polyline you want to use for the flight plan. When you have finished right click the layer and select Stop Editing.
A shape file will be generated under the Flight Paths folder in the root project directory.
Go back to the 3D Viewer and press the Select a Flight Plan button in the toolbar ( 
)
If you saved your flight path layer in the default location, then the form will automatically select the shapefile for you. Otherwise, find the flight path shapefile using the Browse button.
Next, select the polyline from the list on the bottom left of the form.
| Option | Description |
|---|
Constant Elevation
| The elevation of the viewer will stay constant throughout the flight path. The elevation can still be changed as described in Changing Elevation section |
Offset From The Terrain
| Follows the elevation of the terrain at the viewer's position at a constant offset. The elevation can still be changed as described in Changing Elevation section. (Not Implemented Yet) |
Always Look Forward
| The viewer's rotation will stay locked along the polyline. No need to change rotation of the viewer in this mode. Changing the view while the flight path is running will pause the flight plan Pitch is the angle the viewer is looking up or looking down. It can be changed while the flight plan is running. |
Allow Free Look
| The viewer's rotation will behave the same as before. Changing the view will not pause the flight plan |
| Start From First/Last Point in Polyline | Where to start on the polyline. Starting from the first point will cause the viewer to go towards the last point. Starting from the last point will cause the viewer to go to the first point |
Tool |
| Description |
|---|
Play/Pause Flight Plan
|  / 
| Continues the flight plan along the flight path, or pauses the flight plan. If the flight plan is paused, the viewer can move freely anywhere. When the flight plan is resumed the viewer will go back along the flight path. |
Restart | | Restarts the flight plan to either the first point in the flight path or the last point, depending on what direction the flight plan is moving. |
Change Direction
|  / 
| Changes the direction of the flight plan. The arrow indicates the current direction. |
Lock/Unlock Camera
|  / 
| When the lock is on this icon, the view will always look forward as described above. When there is no lock then the view is in free look mode, as described above. |
Pitch
| | The pitch in degrees, which is the angle at which the viewer is looking up or down. |
An example 3D Perspective plot is shown in Figure 8-18. The older X-Y-Z Perspective Plot of 1D cross sections is still available from the View menu.
Figure 8 18. Example 3D Perspective Plot.
