Object vs. Command Output

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You can generate visualization in FreeFlyer in two basic ways:

Using Output commands: FreeFlyer generates visualization when an output command is placed in the Mission Sequence.

Using Output objects: define the visualization settings within the appropriate output object. FreeFlyer generates visualization in two different ways depending on your selection in the output window Editor:

oVisualization appears and updates when an Update command appears in the Mission Sequence

oVisualization updates with each propagation step




For most output-related commands in FreeFlyer, there is a corresponding object that can accomplish the same goal. Generally, the command will be quicker and easier to use, but the object provides greater flexibility and more customizable options. A table of the available output objects and their corresponding commands is shown below.





Plot, Monitor, PolarPlot, PolarMonitor


View, Map






To explain the differences between these two output types further, we will consider the ViewWindow object and the View command. Both of these functionalities can display objects in a 3D Mission View - this is a view of one or more Spacecraft orbiting a central body such as Earth, possibly displaying additional objects such as GroundStations and Sensors.


Why use a ViewWindow instead of a View command?

A ViewWindow provides all the functionality of its matching command, but additionally provides control over when updates occur and offers additional features for controlling the data sent to the Window. An overview of the customizability of a ViewWindow is given below.



How do I use a Window Object?

The guidelines discussed below use the ViewWindow object as an example, but these also apply to PlotWindows, DataTableWindows, and WatchWindows.


1.Add a ViewWindow object to your Mission Plan using the Add menu in the Object Browser.

2.Double-click on the ViewWindow to open its Content page, and select the objects that you would like to view in the output window.

3.On the Solar System page, you can choose which celestial objects are displayed.

4.The Viewpoints page allows you to create one or multiple viewpoints for each output window. On this page, you can choose your Viewpoint type and customize the properties of your camera.

5.On the Properties page, you can choose a Title for your window; for other output objects such as the PlotWindow, additional options are available for subtitles, axis labels, and more.


Note: For Mission Plans still using millisecond precision mode, the Properties page also lets you define the Update Mode of the ViewWindow. As of FreeFlyer 7.3, the default timing precision mode is nanosecond precision mode which provides more modern and robust interfaces for this functionality, the WhileStepping and WhileManeuvering loops. In millisecond timing precision mode, you can select to Update Manually With Update Command, which gives you control over when the Mission Views updates using the Update command, or to Update Automatically Every Step, which updates the ViewWindow with each propagation step. Updating automatically is often easiest for simple analysis, but is not recommended for complex Mission Plans involving multiple Spacecraft. You can also set it to use the Target Display Mode, which forces windows to update automatically during every iteration of a Target sequence.



See Also