Defining an Area Target's Center Point
The options on the Centroid page enable you to define the "center" point of an area target. The centroid is used as, among other things, a terminal point for access lines drawn to the area target during animation.
If an area target's boundaries are defined using a pattern, the centroid can appear in locations other than the center, including locations that lie far outside the area target.
You can also position the centroid by clicking in the 2D Graphics window. If you use the mouse in the 2D Graphics window to position the centroid, be sure that the Basic Centroid page is open and Auto Compute Centroid is disabled. You do not need to click OK or Apply after you have positioned the centroid in the 2D Graphics window. You will need to click OK or Apply if you have made any other changes on the Centroid properties page.
For more information on setting object properties using the mouse, see Mouse Shortcuts.
The options available for defining an area target's centroid depend on the Position Type. To set the position of the centroid manually, enter the desired coordinates or click the desired location in the 2D Graphics window. If you select the Auto Compute Centroid option, STK calculates the centroid position for you.
The Auto Compute Centroid option is not available for elliptical area targets.
To define a local time for the area target, select the Local Time Offset from GMT option and enter the time offset in the adjacent field. For example, to specify a local time offset corresponding to Eastern Standard Time (EST), enter a value of -5.0 hours. If the target is located in a region of EST that practices daylight savings time, the value would be -4.0 hours for epochs occurring during daylight savings time. The offset is constant and doesn't account for daylight savings time rules, which specify when to switch back and forth from standard time to daylight savings time.
If the Use terrain data for altitude update is available and you select it, certain position parameters are disabled, depending on the Position Type.