Working with Multi-Track Objects

STK Pro, STK Premium (Air), STK Premium (Space), or STK Enterprise
You can obtain the necessary licenses for this tutorial 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 capability of the Ansys Systems Tool Kit® (STK®) digital mission engineering software:

  • STK Pro

Problem statement

Engineers and operators need a way to display a large amount of data within an STK scenario for efficient visualization purposes. Such tracks of time-dependent positional data points — tracks like the flights paths of aircraft, the tracks of ground vehicles, test measurements, and the positions of facilities and other objects — can add valuable context to the broader mission environment. Because the STK application automatically computes data such as To Vectors and Lighting Intervals for all STK objects in a scenario, defining them as individual, analytical STK objects can unnecessarily increase the file size of the scenario as well as computation times. You need a way to visualize such assets without adding needless complexity to your scenario; in this case, you want to visualize the routes of two "blue" vehicles and two "red" vehicles over time.

Solution

Use a Multi-Track Object (MTO) to group together many moving or stationary objects to display a large amount of non-analytical data within a scenario. Understanding MTOs is a key prerequisite for organizing track measurements in the Ansys Test and Evaluation Tool Kit (TETK)™ capability's Tracks workflow and for creating individual real-time tracks, or entities, with the Real-Time Tracking Technology (RT3) capability. MTOs are also used with the Conjunction Analysis capability’s Launch Window Analysis tool.

What you will learn

Upon completion of this tutorial, you will be able to:

  • Create an MTO using the graphical user interface (GUI)
  • Change the appearance of MTO tracks in the 2D Graphics window
  • Modify the view of an MTO in the 3D Graphics window

Creating a new scenario

First, you must create a new scenario, then build from there.

  1. Launch the STK () application.
  2. Click Create a Scenario in the Welcome to STK dialog box.
  3. Enter the following in the New Scenario Wizard:
    OptionValue
    NameMTO_Scenario
    LocationDefault
    StartDate: Default / Time: 17:00:00.000 UTCG
    Stop+ 10000 sec
  4. Click OK when you finish.
  5. Click Save () when the scenario loads.

    6. The STK application automatically creates a folder with the same name as your scenario for you.

  6. Verify the scenario name and location when the Save As dialog box opens.
  7. Click Save.

Changing the date format

Change the scenario's date format to epoch seconds by updating its units of measure.

  1. Right-click on MTO_Scenario () in the Object Browser.
  2. Select Properties () in the shortcut menu.
  3. Select the Basic - Units page when the Properties Browser opens.
  4. Click on DateFormat - Current Unit (for example, Gregorian UTC (UTCG)) in the Dimension List panel.
  5. Open the Current Unit drop-down list.
  6. Select Epoch Seconds (EpSec).

    7. The epoch is calculated as time elapsed relative to the scenario epoch.

  7. Select the Tab key.
  8. Click Apply to confirm your change and to keep the Properties Browser open.

Turning off streaming terrain

You will not be using terrain analytically in this scenario, so you can disable streaming terrain. This will also allow the tracks to be displayed more clearly on the surface of the default WGS84 ellipsoid.

  1. Select the Basic - Terrain page.
  2. Clear the Use terrain server for analysis check box in the Terrain Server panel.
  3. Click OK to confirm your change and to close the Properties Browser.

Configuring the 2D Graphics window properties

Configure the 2D Graphics window for a simpler display by updating its Imagery and Details properties.

  1. Bring the 2D Graphics window to the front.
  2. Click Properties () on the 2D Graphics window's 2D Window Defaults toolbar.
  3. Select the Imagery page when the Properties Browser opens.
  4. Clear the Show check box in the Background Image panel.
  5. Select the Details page.
  6. Click to select the following options in the Map Details panel:
    • RWDB2_Coastlines (selected by default)
    • RWDB2_International_Borders
    • RWDB2_Islands
    • RWDB2_Lakes
  7. Click OK to confirm your changes and to close the Properties Browser.

Creating a Multi-Track Object

Insert a Multi-Track Object into the scenario. A Multi-Track Object is a graphical object that contains tracks representing time and positional data. The tracks share the same basic property set for efficient visualization, particularly for displaying a large amount of data within a scenario.

Displaying the Multi-Track Object in the Insert STK Objects tool

You must first add the Multi-Track Object to the Insert STK Objects tool to be able to insert it into your scenario.

  1. Bring the Insert STK Objects () tool to the front.
  2. Click Edit Preferences....
  3. Ensure the New Object page is selected when the Preferences dialog box opens.
  4. Select the Show check box for the MTO Object in the Define Default Creation Methods panel.
  5. Click OK to confirm your selection and to close the Preferences dialog box.

Inserting a new Multi-Track Object

Insert a new Multi-Track Object.

  1. Select MTO () in the Select An Object to Be Inserted list.
  2. Select Insert Default () in the Select A Method list.
  3. Click Insert....

Creating new tracks

Data sets are organized into tracks. Add four tracks to your MTO on the Tracks page.

  1. Open MTO1's () Properties ().
  2. Select the Basic - Tracks page when the Properties Browser opens.
  3. Click New four times to add four tracks to the Track table.

The Track table lists the tracks created in the MTO object, and gives basic information about each. You should have four tracks; each has an ID number, which cannot be modified, auto-populated in sequential numeric order.

Modifying a track

Modify the track data of the first track to define the route of the Blue Ship.

  1. Select the first track (Id: 1) in the Track table.
  2. Click Modify....
  3. Enter Blue Ship in the Name field when the Modify Track Data dialog box opens.

    4. If desired, the track name, as a label, can be displayed in the 2D and 3D Graphics windows, along with a track marker.

  4. Click Insert Point in the Points panel.
  5. Double-click on the appropriate field in the Points table to enter the following data. Select the tab key after each input:
    6. Option Value
    Time 0.0 EpSec
    Latitude 42.4 deg
    Longitude -86.6 deg
    Altitude 0 km
  6. Click Insert Point to create a second point.
  7. Set the following values for the second point:
    8. Option Value
    Time 10000 EpSec
    Latitude 43.1 deg
    Longitude -86.5 deg
    Altitude 0 km
  8. Select the Interpolate Position check box.

    9. The track's marker and label position will be linearly interpolated between the track points for the current animation time, producing a smoother animation.

  9. Click OK to confirm your changes and to close the Modify Track Data dialog box.
  10. Click Apply to confirm your changes and to keep the Properties Browser open.

Viewing the Blue Ship track in the 2D Graphics window

Take a look at the track of the Blue Ship.

  1. Bring the 2D Graphics window to the front.
  2. Zoom in on the Great Lakes region of the United States.
  3. Click Start () on the Animation toolbar.

    4. blue ship location

    You should see a point marker representing the Blue Ship moving in a northeasterly direction along a track on the eastern side of Lake Michigan.

  4. Click Reset () when you are finished.

Modifying the other three MTO tracks

Add the other three tracks to your MTO.

  1. Return to MTO1's () Properties ().
  2. Using the same procedure as with the Blue Ship track, modify the other tracks as follows:

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

    Track Id Name Point Time Latitude Longitude Altitude Interpolate Position
    2 Red Ship 1 0.0 EpSec 42.7 deg -87.6 deg 0 km Selected
    2 6000 EpSec 43.4 deg -87.0 deg 0 km
    3 10000 EpSec 43.3 deg -86.5 deg 0 km
    3 Blue Truck 1 0 EpSec 40.8 deg -84.4 deg 0 km Selected
    2 5000 EpSec 41.2 deg -85.0 deg 0 km
    3 10000 EpSec 41.8 deg -85.3 deg 0 km
    4 Red Truck 1 0 EpSec 43.2 deg -86.1 deg 0 km Selected
    2 7000 EpSec 42.2 deg -85.7 deg 0 km
    3 10000 EpSec 42.1 deg -85.0 deg 0 km
  3. After inserting all of the track points, click Apply to confirm your changes and to keep the Properties Browser open.
  4. Bring the 2D Graphics window to the front.
  5. Click Start () on the Animation toolbar.

    6. markers and tracks

    You should now see simple point markers and tracks for all four of your objects move along the paths you defined in each MTO track.

  6. Click Reset () when you are finished.

Though you have manually defined the MTO tracks in this scenario, you can also load an ephemeris file (*.e) to define the points for an individual track. You can also modify MTO positions and properties through automated processes interacting with the STK application, such as those associated with the TETK and RT3 capabilities.

Configuring the 2D Graphics Track Attributes

Make the MTO graphics easier to see and understand by updating the MTO's 2D Graphics Track Attributes.

Changing all the tracks' line widths

Make each track's lines thicker by selecting all the tracks and opening the Modify Track Graphics Data panel.

  1. Return to MTO1's () Properties ().
  2. Select the 2D Graphics – Track Attributes page.
  3. Click Select All.
  4. Click Modify....
  5. Open the Line Width drop-down list in the Track Line panel when the Modify Track Graphics Data dialog box opens.
  6. Select 3.
  7. Click OK to confirm your selection and close the Modify Track Graphics Data dialog box dialog box.
  8. Click Apply to confirm your change and to keep the Properties Browser open.

Changing marker styles

To make it easier to identify the types of objects represented in the 2D Graphics window, you can also change their marker styles.

  1. Use Ctrl+Click to multi-select both the Blue Ship and Red Ship tracks in the Track table.
  2. Click Modify....
  3. Open the Marker Style drop-down list when the Modify Track Graphics Data dialog box opens.
  4. Select the Ship () icon.
  5. Click OK to confirm your selection and to close the Modify Track Graphics Data dialog box.
  6. Multi-select both the Blue Truck and Red Truck tracks in the Track table.
  7. Click Modify....
  8. Open the Marker Style drop-down list when the Modify Track Graphics Data dialog box opens.
  9. Select the Ground Vehicle () icon.
  10. Click OK to confirm your selection and to close the Modify Track Graphics Data dialog box.
  11. Click Apply to confirm your changes and to keep the Properties Browser open.

Changing the "blue" vehicles' track colors

You can use color to distinguish between the "blue" and "red" vehicles. Start with the "blue" vehicles.

  1. Multi-select both the Blue Ship and Blue Truck tracks in the Track table.
  2. Click Modify....
  3. Open the Color drop-down list when the Modify Track Graphics Data dialog box opens.
  4. Select blue.
  5. Click OK to confirm your selection and to close the Modify Track Graphics Data dialog box.
  6. Click Apply to confirm your changes and to keep the Properties Browser open.

Changing the "red" vehicles' track colors

Now, repeat the process for the "red" vehicles.

  1. Multi-select both the Red Ship and Red Truck tracks in the Track table.
  2. Click Modify....
  3. Open the Color drop-down list when the Modify Track Graphics Data dialog box opens.
  4. Select red.
  5. Click OK to confirm your selection and to close the Modify Track Graphics Data dialog box.
  6. Click Apply to confirm your changes and to keep the Properties Browser open.

Viewing the tracks in the 2D Graphics window

View the tracks of the MTO in the 2D Graphics window.

  1. Bring the 2D Graphics window to the front.
  2. Click Start () on the Animation toolbar.

    3. 2D View of the MTO paths

    You should now see two Ship markers and two Ground Vehicle markers and their tracks.

  3. Click Reset () when you are finished.

You can also display lines between a Scenario object and tracks in an MTO (and between tracks inside an MTO) by updating the Object Lines properties of a 2D or 3D Graphics window.

Configuring the 3D Graphics Track Attributes

You can replace the object markers with models of the ships and ground vehicles in the 3D Graphics window with 3D models by updating the MTO's 3D Graphics Track Attributes.

Updating the 3D Graphics track attributes

The 3D Graphics Track Attributes page is used to configure the visualization of tracks in the 3D Graphics window.

  1. Return to MTO1's () Properties ().
  2. Select the 3D Graphics – 3D Track Attributes page.
  3. Select the Blue Ship track in the Track 3D table.
  4. Click Modify....

Modifying the 3D Track graphics

The Modify Track 3D Graphics Data dialog box is used to define the 3D graphics attributes of the selected track or tracks.

  1. Select the Show check box in the Model panel when the Modify Track 3D Graphics Data dialog box opens.
  2. Click the Model File ellipsis ().
  3. Open the Sea folder (<Install Dir>\STKData\VO\Models\Sea) when the File dialog box opens.
  4. Select ship.glb.
  5. Click Open to confirm your selection and to close the File dialog box.
  6. Set the Log Scale to 2.2.
  7. Clear the Z Points toward Nadir check box.

    8. This will orient the 3D model as a surface vehicle.

  8. Click OK to confirm your changes and to close the Modify Track 3D Graphics Data dialog box.
  9. Repeat the above procedure to modify the settings for the other tracks as follows:
    10. Track Id Name Model - Show Model File Log Scale Z Points Toward Nadir
    2 Red Ship Selected <Install Dir>\STKData\VO\Models\Sea\cruise_liner.glb 2.0 Cleared
    3 Blue Truck Selected <Install Dir>\STKData\VO\Models\Land\humvee.glb 3.2 Cleared
    4 Red Truck Selected <Install Dir>\STKData\VO\Models\Land\military-truck.glb 3.2 Cleared
  10. Click Apply to confirm your changes and to keep the Properties Browser opens.

The 3D Graphics window now shows models for the objects instead of the 2D points used previously.

Setting the view to an MTO track

You can use the View From/To dialog box to center your view on one of the MTO paths by enter the Id of a track. This ID will be referenced when working with other tools.

  1. Select the Basic – Tracks page.
  2. Set the Computation Track Id to 3.
  3. Click OK to confirm your change and close the Properties Browser.
  4. Bring the 3D Graphics window to the front.
  5. Click View From/To () on the 3D Graphics window's 3D Graphics toolbar.
  6. Select MTO1 () in the From Position field when the View From/To: 3D Graphics 1 - Earth dialog box opens.
  7. Click OK to confirm your selection and to close the View From/To: 3D Graphics 1 - Earth dialog box.
  8. Move around in the 3D Graphics window to get a view of the tracks and models.

3D View of the MTO paths and Models

The view will be centered on the Blue Truck, which is track number 3. By changing the Computation Track Id, you can change which path the view will be centered on when selecting the MTO as the View From/To object.

Using the Get Info tool with Multi-Track Objects

The Get Info tool is used to return data about STK objects from the 3D Graphics window. It can be used to return information about and act on tracks in MTO objects.

  1. Zoom out on the 3D Graphics window so that you can see all four (4) tracks.
  2. Select Utilities in the Menu Bar.
  3. Select Get Info Tool... () in the Utilities menu.
  4. Click Enable object selection pick in 3D window () when the Get Info Tool window opens.
  5. Click and hold in the 3D Graphics window to draw a rectangular selection box around all four tracks.

    6. Get Info Tool: Object Selection Box

  6. Select one of the MTO1 entries in the STK Objects list in the Get Info Tool.
  7. View details about the track in the right-hand panel.

Get Info tool: MTO tracks

Note the track ID is displayed along with other information about the track.

When an MTO is part of the RT3 layer, you can use the Get Info tool to promote a selected track to a "heavy" STK object to analyze its data or demote a track back to an MTO.

Saving your work

Clean up your workspace and close out your scenario.

  1. Close the Get Info tool
  2. Save () your work.
  3. Close the scenario when you are finished.

Summary

This tutorial provided a basic introduction to Multi-Track Objects the STK application. You used the GUI to create a new MTO, define several tracks, and update the tracks' 2D and 3D graphics properties. By creating a an MTO, you were able to visualize different tracks without relying on resource-heavy analytical components. By using MTOs with other, more advanced STK capabilities, you can visualize and organize your test data tracks to have at the ready for analysis.