Part 11: Compute Coverage Over Regions

This training requires additional licenses to complete. You can obtain the necessary license for the training by visiting http://licensing.agi.com/stk/evaluation or calling AGI support.

STK Coverage

The STK Coverage module allows you to analyze the global or regional coverage provided by one or more assets (facilities, vehicles, sensors, etc.) while considering all access. Specific results are generated based on detailed access computations performed to user-defined grid points within an area of coverage.

There are two case studies that showcase AGI's Coverage capability: Missile Flight Test Planning and Analysis with STK and Joint Navigation Warfare Center's Common Operating Environment.

Using STK Coverage you can:

  • Select regions of interest.
  • Define coverage assets (satellites, ground facilities, etc.).
  • Define the time period of interest.
  • Determine and report measures of coverage quality.

Define Coverage and Compute Accesses from the Assets to the Grid

Watch the following video, then follow the steps below incorporating the systems and missions you work on (sample inputs provided).

  1. Create a new scenario with the default time period.Closed
    1. Click the Create a Scenario () button.
    2. In the New Scenario Wizard, set the following options:
      1. Enter a Name for the scenario (e.g. STK_Coverage).
      2. Define the analysis start and stop times or accept the defaults.
    3. Click OK.
  2. Model an Area Target () using one of the available methods.Closed
    • Insert an Area Target using the Select Countries and US States method.
      1. Select United_States in the list on the left..
      2. Click Insert.
      3. Click Close to dismiss the Select Countries and US States window.
  3. Model at least one moving vehicle (, , ) that passes over the region of interest/area target during the analysis time using one of the available methods.Closed
    1. Insert a Satellite () using the Define Properties method and click OK to accept the default parameters and dismiss the Properties Browser.
    2. Insert an Aircraft () by typing in waypoint values.

        3. Example waypoint values

      • First waypoint: Lat = 39 deg, Lon = -120 deg.
      • Second waypoint: Lat = 40 deg, Lon = -77 deg.
  4. Model a default sensor () on the moving object.Closed
    1. In the Insert STK Objects () tool, select sensor ().
    2. Select the Insert Default as the Select A Method option.
    3. Click the Insert... button.
    4. Select the moving vehicle in the Select Object window.
    5. Click OK.
  5. Insert a Coverage Definition () using the Define Properties method.Closed

      6. You may need to add the Coverage Definition object to the Insert STK Objects tool. To do this, click the Edit Preferences button and select it from the New Object tool.

      1. Define the Coverage Definition.
      2. Use the area target () to define the grid.Closed
        1. On the Basic - Grid page, set the Type option to Custom Regions.
        2. Click the Select Regions... button.
        3. Move () the area target (e.g. United States) in the Area Targets list to the Selected Regions field. You can also double-click the area target you'd like to move.
        4. Click OK to dismiss the Select Regions window.
        5. Click Apply to apply changes and keep the Properties Browser open.
      3. Define the grid Point Granularity.
        1. On the Basic - Grid page, in the Point Granularity text field, enter the desired Lat/Lon value (e.g. 0.25 deg).
        2. Click Apply to apply changes and keep the Properties Browser open.
      4. Define the grid Point Altitude.Closed
        1. On the Basic - Grid page, locate the Point Altitude section.
        2. Select the Altitude above Terrain option from the drop-down list.
        3. Keep the altitude at the zero (0) km default value.
        4. Click Apply to apply changes and keep the Properties Browser open.
      5. Assign the vehicle(s) as Assets.Closed
        1. Select the Basic - Assets page.
        2. Click the object(s) in the Assets list (e.g. Aircraft1 or Satellite1) and click Assign.
        3. Click Apply to apply changes and keep the Properties Browser open.
      6. Disable the option to Automatically Recompute Access.Closed
        1. Select the Basic - Advanced page.
        2. Disable the Automatically Recompute Access option.
        3. Click OK to apply changes and dismiss the Properties Browser.
      7. Right-click the Coverage Definition () object in the Object Browser, select the CoverageDefinition menu, and click compute Accesses.

Constraints can be applied to each grid point by selecting an object or the instance of an object. If you select an object, the constraints set for the object are also applied to used by all points within the grid.

Coverage Quality

While the coverage definition () defines the problem, the Figure(s) of Merit () allows you to evaluate the quality of coverage provided by the selected set of assets (defined for the coverage definition object) over the coverage area and then provide a method for summarizing and viewing the resultant data.

To evaluate coverage quality, you will first need to set basic parameters that determine the way in which quality is computed, which involves:

  • Choosing the method for evaluating the quality of coverage provided.
  • Setting measurement options.
  • Identifying the criteria needed to achieve satisfactory coverage.

Figures of Merit can exhibit two types of behavior: dynamic and static. The dynamic behavior of a Figure of Merit allows you to compute values corresponding to a specific time. Not all Figures of Merit can exhibit dynamic behavior. Those which do not exhibit dynamic behavior are not able to compute time-dependent information.

Measure the Quality of Coverage

Watch the following video, then follow the steps below incorporating the systems and missions you work on (sample inputs provided).

a.

  1. Create a simple Coverage Figure of Merit.
    1. Attach a default Figure of Merit () to the Coverage Definition ().Closed
      1. In the Insert STK Objects tool (), select Figure of Merit ().

        2. You may need to add the Figure of Merit object to the Insert STK Objects tool. To do this, click the Edit Preferences button and select it from the New Object tool.

      2. Select Insert Default from the Select A Method list.
      3. Click the Insert... button.
      4. Select the Coverage Definition () object in the Select Object dialog.
      5. Click OK.
    2. Right-click on the Figure of Merit in the Object Browser, and rename the object (e.g. FOM_SimpleCoverage).
    3. Display the Static Graphics only.Closed
      1. Right-click on the Figure of Merit () and select Properties ().
      2. Select the 2D Graphics - Animation page.
      3. Disable the Show Animation Graphics option. By default, both animation and static graphics are displayed.
      4. Click OK to accept the changes and dismiss the Properties Browser.
    4. Generate a Percent Satisfied report for the Figure of Merit ().Closed
      1. Right-click on the Figure of Merit () in the Object Browser and select Report & Graph Manager.
      2. Disable the Show Graphs option located in the Styles field. You are only interested in the reports so you can declutter the Styles window by removing the graphs.
      3. Expand () the Installed Styles directory and select Percent Satisfied.
      4. Click Generate... to display the percent and area satisfied.
    5. Display Animation GraphicsClosed
      1. Right-click the Figure of Merit () and select Properties ().
      2. Select the 2D Graphics - Static page.
      3. Disable the Show Static Graphics option.
      4. Select the 2D Graphics - Animation page.
      5. Enable the Show Animation Graphics option.
      6. Select Accumulation Up to Current Time from the drop-down list.
      7. Click OK to accept the changes and dismiss the Properties Browser.
      8. Animate () the scenario and watch the grids highlight as they meet the satisfaction criteria.
  2. Create a Number of Accesses Figure of Merit.
    1. Attach a default Figure of Merit () to the Coverage Definition ().Closed
      1. In the Insert STK Objects tool (), select Figure of Merit ().

        2. You may need to add the Figure of Merit object to the Insert STK Objects tool. To do this, click the Edit Preferences button and select it from the New Object tool.

      2. Select Insert Default from the Select A Method list.
      3. Click the Insert... button.
      4. Select the Coverage Definition () object in the Select Object dialog.
      5. Click OK.
    2. Right-click on the Figure of Merit in the Object Browser, and rename the object (e.g. FOM_NumAccesses).
    3. Define the Figure of Merit.Closed
      1. Select the Basic - Definition page.
      2. Select the desired Figure of Merit Type (e.g. Number of Accesses).
      3. Select the desired Compute method (e.g. Total), if applicable (depends on the Figure of Merit type).
      4. Click Apply to apply the changes and keep the Properties Browser open.
    4. Display the Static Graphics only.Closed
      1. Select the 2D Graphics - Animation page.
      2. Disable the Show Animation Graphics option. By default, both animation and static graphics are displayed.
      3. Select the 2D Graphics - Static page.
      4. Enable the Show Contours option.
      5. Click the Remove All button to remove the default levels in the Level Attributes field.
      6. Enter the desired Start, Stop, and Step levels.
        • Start = Minimum FOM value in Grid Stats report.
        • Stop = Maximum FOM value in Grid Stats report.
        • Step = 1.
      7. Click OK to accept the changes and dismiss the Properties Browser.
    5. Generate a Grid Stats report for the Figure of Merit ().Closed
      1. Right-click on the Figure of Merit () in the Object Browser and select Report & Graph Manager.
      2. Disable the Show Graphs option located in the Styles field. You are only interested in the reports so you can declutter the Styles window by removing the graphs.
      3. Expand () the Installed Styles directory and select Grid Stats.
      4. Click Generate... to display the static Figure of Merit range.
    6. Display Animation GraphicsClosed
      1. Right-click the Coverage Definition () and select Properties ().
      2. Select the 2D Graphics - Static page.
      3. Disable the Show Static Graphics option.
      4. Select the 2D Graphics - Animation page.
      5. Enable the Show Animation Graphics option.
      6. Select Accumulation Up to Current Time from the drop-down list.
      7. Enable the Show Contours option.
      8. Click the Copy Static Levels button.
      9. Click OK to accept the changes and dismiss the Properties Browser.
      10. Animate () the scenario and watch the grids highlight as they meet the satisfaction criteria.

The static behavior for a Figure of Merit specifies the value of quality over the entire coverage period. Depending on the size of the coverage problem being analyzed, the computation of the static values for each grid point can be time consuming. For this reason, the static values are cached to allow for rapid generation of reports and modifications to graphical representations once the static values have been computed. The computed static values will also be saved and restored with the scenario if the SaveMode of the parent Coverage Definition object is set to "Save accesses."

Don't forget to save your work!

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