Working with Multitrack Objects

STK Pro, STK Premium (Air), STK Premium (Space), or STK Enterprise
You can obtain the necessary licenses for this training by contacting AGI Support at support@agi.com or 1-800-924-7244.

The results of the tutorial may vary depending on the user settings and data enabled (online operations, terrain server, dynamic Earth data, etc.). It is acceptable to have different results.

Capabilities Covered

This lesson covers the following STK Capabilities:

  • STK Pro

What You Will Learn

This tutorial is an introduction to the Multi-track object (MTO) in STK. In this exercise you will:

  • Create a Multi-track Object (MTO)
  • Change the appearance of MTO tracks in the 2D map window
  • Modify the view of an MTO in the 3D VO window.

Multi-track Objects are used within 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 are the most efficient way to quickly display a large number of objects within STK. However, MTOs can be used only for visualization. If you want to provide analysis of your objects, such as graphs, reports and access calculations, you cannot use a multi-track object.

For this tutorial, you will create and visualize the paths of a friendly ship and ground vehicle, and an enemy ship and ground vehicle.

Create a New Scenario

  1. Start STK and create a new scenario. Define the scenario's Time Period as follows:
    2. Option Value
    Start 1 Aug 2015 15:00:00.00
    Stop + 1 day
  2. Under Scenario > Properties >the Units page, change the DateFormat to Epoch Seconds (EpSec).
  3. Extend the Insert menu and select New to launch the STK Insert Objects tool.
  4. When Insert STK Objects tool appears, click the Edit Preferences... button.
  5. Enable the MTO object.
  6. Select the MTO object () and Insert Default to insert a default MTO. Open the Basic - Tracks Properties page. This page displays all tracks that are part of the MTO.
  7. Click the New button four times to add four tracks to this MTO. Each track represents one vehicle.
  8. Highlight the first track and click the Modify... button. Name this track Friendly Ship, and then click the Insert Point button. Double-click on each field for the first point, and insert the following data:
    9. Option Value
    Time 0 EpSec
    Latitude 42.4 deg
    Longitude -86.6 deg
    Altitude 0 km
  9. Click on the Insert Point button again, and modify the second point with the following data:
    10. Option Value
    Time 10000 EpSec
    Latitude 43.1 deg
    Longitude -86.5 deg
    Altitude 0 km
  10. Select the Interpolate Position box to make sure that the track computes intermediate points from one point to the next as you animate. After modifying the two points, click OK, and then click Apply in the MTO Basic - Tracks window.
  11. In the 2D Graphics window and in the 3D Graphics window, zoom in on the Great Lakes area (or a rectangle roughly centering on 42 degrees latitude, -86 degrees longitude) and animate the scenario. You should see a marker representing your "Friendly Ship" track move along the east side of Lake Michigan.
  12. Return to the Property page of your MTO. Modify the other tracks as follows, making sure that the Interpolate Position box is checked for each track:

    13. STK will automatically rearrange the points by time, so after entering the data for point #2, it may jump to the #3 position.

MTO Tracks

Track Name Point Time Latitude Longitude Altitude

Track Name Point Time Latitude Longitude Altitude
2 Enemy Ship 1 0.0 42.7 -87.6 0
2 6000.0 43.4 -87.0 0
3 10000.0 43.3 -86.5 0
3 FriendlyTruck 1 0.0 40.8 -84.4 0
2 5000.0 41.2 -85.0 0
3 10000.0 41.8 -85.3 0
4 EnemyTruck 1 0.0 43.2 -86.1 0
2 7000.0 42.2 -85.7 0
3 10000.0 42.1 -85.0 0
  1. After inserting all of the track points, click OK on Basic - Tracks page and animate the scenario. You should now see all four of your objects move along the MTO paths.
  2. Bring up the properties window for the MTO again. Go to the 2D Graphics – Track Attributes page. Click the Select All button and then the Modify button. Change the Line Width value to 3 and click OK.
  3. Click Apply On the 2D Graphics – Track Attributes page, and you should see that the paths displayed are now thicker.
  4. To make it easier to identify the types of objects represented, you will now change the markers for the paths. On the 2D Graphics – Track Attributes page, highlight the first path and hold down the Ctrl key while clicking on the second path to multi-select the two ships. Click the Modify button. Change the marker style to the ship icon and click OK. Then, multi-select tracks 3 and 4, and change their marker style to the ground vehicle icon.
  5. You can use color to distinguish between "friendly” and “enemy” vehicles. On the 2D Graphics – Track Attributes page, select tracks 2 and 4 and click Modify. Using the drop-down selection, change the Color to red and click OK. If they are not already green, use the same procedure to set tracks 1 and 3 to green. Click Apply.
  6. Animate the scenario. You should now see two ship icons and two ground vehicles. The red paths represent enemy vehicles and the green paths represent friendly vehicles.

    7. 2D View: MTO's

  7. Open the 3D Graphics – 3D Track Attributes page for the MTO. Highlight track 1 and click Modify. Select the Show box in the Model area and click the ellipsis () button next to Model File. Select the file ship.mdl in the Sea directory, set the log scale to 2.0, disable the Z Points toward Nadir box, and click OK.
  8. Repeat the above procedure to make the following settings for the other tracks:

MTO 3D Model Selections

Track Model File Log Scale Z Points Toward Nadir
2 Sea\aegis-destroyer.mdl 2.3 No
3 Land\military-truck.mdl 3.5 No
4 Land\humvee.mdl 3.5 No
  1. Click Apply and animate the scenario. The 3D Graphics window now shows models for the objects as they travel along the MTO tracks.
  2. To set your view to one of the MTO paths, bring up the MTO's property browser. On the Basic – Tracks page, set the Computation Track Id to 3 and click Apply.
  3. On the 3D Graphics toolbar, click the View From/To () button. Select the MTO in the View From field and click OK. The view will now be centered on the friendly truck, which is track number 3. By changing the Computation Track Id, you can change which path the view will be centered on when the MTO is selected as the View From/To object.

This tutorial provided an introduction to Multi-track Objects in STK. Although they cannot be used for numerical analysis, MTOs provide a way to efficiently display the positions of hundreds or thousands of objects in STK.

The MTO paths in this activity were defined with the graphical user interface. However, MTO positions and properties can also be modified through automated processes interacting with STK.