Understanding Object Hierarchy

When an object is introduced into a scenario, it appears in the Object Browser. The Object Browser displays each object in a scenario and the children of each object. A plus or minus sign appears to the left of some objects, indicating that you can collapse or expand the object tree of the selected item to hide or show its children. The following are common STK objects:

Vehicles

A vehicle is an object that changes its position and orientation over time. The vehicle class includes all satellites , aircraft , ships , ground vehicles , missiles , and launch vehicles . Vehicles can have children such as sensors, receivers, and transmitters.

Facilities and Targets

Facilities and targets are non-mobile points on the Earth's surface. Typically, facilities mark the position of ground stations, launch sites, tracking stations, etc. Targets can be used to represent points of interest for sensor coverage, locations of cities, etc. Facilities and targets can have children such as sensors, receivers, and transmitters.

Sensors

Sensor performance is a major concern for satellite system engineers and integrators. Sensors can be used to represent such equipment as optical or radar sensors, receiving or transmitting antennas, and lasers. The sensor object can also be useful for defining another object's field of view. Sensors are children of vehicles, facilities and targets. The sensor object can also have children of its own.

Planets and Stars

Complex scenarios often include planets and stars to provide a complete analysis of sensor in-view opportunities. Planets represent objects in heliocentric orbit such as planets, minor planets, asteroids, and comets. STK also includes the Moon and the Sun in the Planet class. Planets can have children such as receivers and transmitters. In STK, the star object is used to represent "stationary" objects such as stars, quasars, and pulsars. Unlike planets, stars cannot have children.

Area Targets

Area targets are defined regions of interest on the Earth. They are useful when you need to define a target in terms of a geographical area instead of a specific point on the Earth's surface. Area targets cannot have children.

Line Targets

Line Targets are objects that define a line connecting selected points on the surface of the earth. You can define 2D and 3D graphics properties for a line target, and you can impose various kinds of constraints on it.

Multi-Track Objects (MTOs)

MTOs are used in STK to group together many moving or stationary objects. An MTO consists of multiple tracks. Each track consists of points with time, latitude, longitude, and altitude information. MTOs provide the most efficient way to display a large number of objects quickly in STK. MTOs can be used only for visualization. If you want to provide analysis of objects, such as graphs, reports and access calculations, you cannot use a multi-track object.