Area Target Properties | Line Target Properties

Basic Constraints for Area Targets and Line Targets

Basic Constraints for Area Targets and Line Targets allow you to impose standard access constraints on an area target or line target. These constraints apply to all points within or along the area target or line target. If the constraint is satisfied for at least one point, access to the area target or line target is considered valid.

When an access involves a child object (i.e., sensor, transmitter, receiver, antenna, or radar), use the child object's parent or grandparent in the table below to determine whether the constraint can be used for access to that child object. For example, if a constraint can be used for accesses to all vehicles, then that constraint can also be used for any child object of a vehicle.

In the following table, abbreviations in the Constraints used for accesses to... column are:

F = facility Pl = place T = target V = all vehicles S = satellite M = missile L = launch vehicle
A = aircraft Sh = ship AT = area target LT = line target P = planet St = star
Constraint Description Constraint used for accesses to...
Minimum Elevation If this option is selected, specify the minimum elevation angle between the relative position vector from a point within or along the area target or line target to the object of interest and the local horizontal plane at the point within or along the area target or line target. F Pl T P St V
Line of Sight If this option is selected (default), access to the area target or line target is constrained to when a line of sight is available to some point within or along the area target or line target above the local horizon. F Pl T P St V
Altitude Access to the object is constrained by the minimum and maximum altitude of the object to which the constraint is applied. F Pl T P V
Distance From Boundary

Access is constrained by the signed distance from an area target boundary to the subpoint of the other object, measured along the central body surface (terrain is ignored) and meeting the specified minimum and maximum limits. The distance is first computed as the smallest distance between the subpoint and any point of the area target boundary. Then, if the subpoint lies within the boundary, value is made negative; if the subpoint lies outside the boundary, the value is made positive.

The sign is used to restrict the location of the subpoint when meeting the limits. For example:

  • To model when the subpoint is between 1 km and 2 km of the boundary with the subpoint being inside the area target, you would set a Min value of -2.0 km and a Max value of -1.0 km.

  • To model when the subpoint is within 5 km of the boundary, but also outside the boundary, you would set a Min value of 0.0 km and a Max value of 5.0 km.

  • To model when the subpoint was within 3 km of the boundary, irrespective of whether in or outside the boundary, one would set a Min value of -3.0 km and a Max value of 3.0 km.

 F Pl T P St V
Constraint Setting Description
Access to Whole Object If this option is selected, access to the object is constrained to when it is established to the entire object, as opposed to any part of it.
Use this Maximum Time Step in Access Computations If this check box is selected, access computations will have a maximum time step that you specify in the adjacent field.