Passes | Resolution Options | Leading/Trailing Options

2D Pass Graphics

2D Pass graphics allow you to graphically display a satellite's ground track, and in some cases the orbit path, in the 2D Graphics window. The ground track of a satellite is the portion of the Earth's surface that it covers during its orbit. The orbit path is the actual path that the satellite follows during its orbit. The orbit path will only be displayed when the 2D window uses the Perspective or Orthographic projections.

Passes

Option Description
Show All If selected, the entire ground track for the satellite displays in the 2D Graphics window. You must enable either Show All or Show Pass From/To.
To hide all satellite pass graphics, turn OFF the Inherit Settings and Show options on the satellite's Attributes page.
Show Pass From/To If selected, the portion of the ground track within the specified range displays in the 2D Graphics window. Enter the beginning and end pass numbers. You can enter First instead of a beginning number and Last instead of an ending number.
Visible Sides Choose to display:
  • Ascending - Only the ascending side of each pass is visible.
  • Descending - Only the descending side of each pass is visible.
  • Both - Both sides of each pass, or the entire pass, is visible.
  • None - Neither side of each pass is visible.
Also applies to the display of satellite swaths, access, and animation graphics.
Show Pass Labels If ON, pass numbers are shown at the pass break locations in the 2D Graphics window.
Show Path Labels If ON, the path numbers within a repeating ground track sequence are shown at the pass break locations in the 2D Graphics window.

If both pass numbers and path numbers are displayed in the 2D Graphics window, the numbers will be displayed as pass#/path# at the pass break location.

Resolution

Click the Resolution button to display the Path Resolution Values window where you can specify the ephemeris steps for vehicle routes, ground tracks, trajectories and orbits.

Ground Track Central Body Display

You can select the central bodies on which the satellite groundtrack will be displayed. By default, the satellite's parent central body is selected and is displayed first in the list. (Available for satellites only.)

Most 2D graphics (time events, contours, swath, for example) will only show on the parent central body for the satellite. In 2D, selecting other central bodies will affect only the 2D graphics groundtrack line, marker, label, and access lines between objects if the other access object can also display on the same central body. In 3D, only the groundtrack line will be displayed on the specified central body that is not the parent central body.

Leading/Trailing Options

Leading/Trailing options for 2D and 3D Graphics are the same for all vehicles in STK.

A Few Words about Repeating Ground Tracks

The repeating ground track sometimes appears clumped or not uniform at higher latitudes. This is because of the Earth's natural precession and nutation. It can be overridden by editing the Earth's central body file (Earth.cb), which can be found in <STK install folder>\STKData\CentralBodies\Earth. If you open this file in a text editor, you will see the following fields:

  • NutationUpdateInterval 1800.0
  • ApplyPoleWander Yes

To disable this effect you should do the following:

  1. Increase the NutationUpdateInterval to a very large number.
  2. Set the ApplyPoleWander to No.
  3. Save the file.
  4. Restart STK.

The ground trace will not correspond to what it should be as you are artificially forcing the Earth's movements in Inertial Space.