Use the Covariance properties page to define the graphical display of a 3D ellipsoid of the covariance for position, velocity, or both.
To display an ellipsoid, you need to load covariance data from an external ephemeris file (*.e).
The Covariance properties page has separate sections for Position Ellipsoid and Velocity Ellipsoid. The following settings appear in both sections except as noted. The main choice is between using Basic settings or Intervals settings.
Basic settings
Selecting the Basic radio button indicates that you want to apply these common graphics settings for the entire scenario time.
| Setting | Description |
|---|---|
| Show | Select this check box to have the ellipsoid appear in the 3D Graphics window and make the other settings in this table available. For the position ellipsoid, this defaults to selected if the ephemeris file for the vehicle includes covariance. |
| Use Vehicle Color | Select this radio button to have the ellipsoid be the same color as the vehicle. Selecting this makes Custom Color unavailable. |
| Custom Color | Select this radio button to have the ellipsoid be the color that you select in the drop-down. Selecting this makes Use Vehicle Color unavailable. |
| Line Width | Use the drop-down to select the width of the ellipsoid lines. |
| % Translucency | Use the slide control to set the translucency of the lines that make up the ellipsoid. You can set the translucency from 0 to 100 percent, where 100 percent is invisible. |
Interval Settings
Selecting the Intervals radio button indicates that you want to apply different graphics settings for each time interval you specify.
| Setting | Description |
|---|---|
| Start | Enter the time at which an interval begins for the graphics defined in the entry to apply to the ellipsoid in the 3D Graphics window. STK uses the Default Attributes values if there is an interval of time not covered by the intervals you specified. |
| Stop | Enter the time at which the interval ends. |
| Show | Select this check box to have the ellipsoid appear during the interval time using the graphics properties set here. If you do not select this check box, the ellipsoid does not appear during the interval time. |
| Color | Select a color for the ellipsoid from the drop-down. |
| Width | Use the drop-down menu to select the width of the ellipsoid lines. |
| % Translucency | Enter a value for the translucency of the lines that make up the ellipsoid. You can set the translucency from 0 to 100 percent, where 100 percent is invisible. |
| Click this to add a covariance interval to the table. | |
| Click this to use interval data from an external file. STK uses interval times in the external file as the display intervals for the ellipsoid. | |
| Click this to import STK Analysis Workbench Time Tool interval component data. STK uses interval times in the interval component as the display times for the ellipsoid. | |
| Click this to remove the selected time period from the Intervals table. | |
| Click this to remove all the intervals from the Intervals table. |
Other settings
These are additional settings available for your ellipsoids.
| Setting | Description |
|---|---|
| Probability | Select this radio button to specify a value. STK uses this specified percentage of probability encompassed by the ellipsoid to indirectly size the ellipsoid. A probability of 95 percent corresponds to a scale of 2.795. This is only available for the Position Ellipsoid, and selecting it makes Scale unavailable for Position Ellipsoid. |
| Scale | Specify a scale value to directly size the ellipsoid. A scale of 1 means that STK uses the position covariance matrix without change. |
| Use curvilinear coordinates | Select this check box to have STK use curvilinear coordinates to display the ellipsoid. |