Air-to-Air Observations with EOIR

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.

Required Capability Install: For versions 12.10 and earlier of the STK software, this lesson requires the installation of the EOIR capability. For these versions of the software, the EOIR installer is included in the STK Premium software download, but requires a separate installation process. Read the Readme.htm found in the STK software install folder for installation instructions. You can obtain the necessary install by visiting https://support.agi.com/downloads or calling AGI support.

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 capabilities of the Ansys Systems Tool Kit® (STK®) digital mission engineering software:

  • STK Pro
  • Electro-Optical Infrared Sensor Performance (EOIR)

Problem statement

Engineers, mission planners, and operators need to determine when an airborne sensor system can detect, track, identify, and characterize targets of interest under operational conditions. You are conducting a test flight of a commercial space launch vehicle from a launchpad at Kennedy Space Center in Florida. You want to track the launch vehicle using an aircraft-mounted mid-wave infrared (MWIR) thermal imaging camera system as it travels along its arc. You want to be able to view the launch vehicle as it would appear in the MWIR camera, including both its body shape and the behavior of its exhaust plume, and to analyze the sensor data.

Solution

Use the STK software's Electro-Optical Infrared Sensor Performance (EOIR) to model an airborne mid-wave infrared observation system and a Missile object to define and build the launch vehicle's EOIR shape and simulate its exhaust plume. Then, generate a sensor scene that shows the launch vehicle and its exhaust plume as it traverses its arc. Optionally, export your EOIR sensor scene frames and stitch them together to create a video of the launch.

What you will learn

Upon completion of this tutorial, you will understand how to do the following:

  • Use the EOIR capability to design an air-based EOIR observation system
  • Model a mid-wavelength infrared camera
  • Model a launch vehicle's EOIR shape using a Missile object
  • Define the behavior and properties of a vehicle's exhaust plume
  • Export EOIR sensor scene frames
  • Create a video from individual still images of an EOIR sensor scene

Creating a new scenario

First, you must create a new STK scenario, and 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 STK: New Scenario Wizard:
    4. Option Value
    Name EOIR_AirObservation
    Start Default Date / Set Time to 16:00:00.000
    Stop + 10 mins
  4. Click OK when you finish.
  5. Click Save () when the scenario loads.

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

  6. Verify the scenario name and location in the Save As window.
  7. Click Save.

Save () often during this lesson!

Disabling streaming terrain

By default, the STK application connects to the Ansys Geospatial Data Cloud to distribute Earth terrain data for analysis and visualization. Turn off streaming terrain, as it is not required for your analysis.

  1. Right-click on EOIR_AirObservation () in the Object Browser.
  2. Select Properties () in the shortcut menu.
  3. Select the Basic - Terrain page when the Properties Browser opens.
  4. Clear the Use terrain server for analysis check box in the Terrain Server panel.
  5. Click OK to confirm your change and to close the Properties Browser.

Modeling the test aircraft

Your airborne test platform consists of an EOIR sensor mounted to a high-altitude research aircraft. Start by modeling the aircraft and its route.

Inserting an Aircraft object

Insert an Aircraft object, to which an EOIR sensor will be attached.

  1. Bring the Insert STK Objects tool () to the front.
  2. Select Aircraft () in the Select An Object To Be Inserted listed.
  3. Select Insert Default () in the Select A Method list.
  4. Click Insert....
  5. Right-click on Aircraft1 () in the Object Browser.
  6. Select Rename in the shortcut menu.
  7. Rename Aircraft1 () TestAcft.

Modeling the aircraft's route

For this scenario, you will model a quick, two-waypoint, high-altitude flight path for the aircraft to observe the space launch vehicle. Use the default Great Arc propagator, which defines the route of a vehicle that follows a point-by-point path along, over, or below the surface of the Earth at a given altitude or depth.

  1. Open TestAcft's () Properties ().
  2. Select the Basic - Route page when the Properties Browser opens.
  3. Note GreatArc is selected for the Propagator by default.

Inserting the route's waypoints

The waypoints that comprise the great arc route are contained in a table that displays each point, along with all of its properties, in sequence. You can use the table to directly edit those properties. One row of values describes a single waypoint in the route of the vehicle. Enter the two waypoints manually.

  1. Leave Smooth Rate set for the Route Calculation Method.

    2. This will use the Speed property of each waypoint to calculate the route between the waypoints.

  2. Click Insert Point.
  3. Enter the following values for the first waypoint by clicking in the associated cell:
    4. Latitude Longitude Altitude
    26.72 deg -76.90 deg 20.00 km
  4. Select the Enter key.
  5. Click Insert Point again.
  6. Enter the following values for the second waypoint:
    7. Latitude Longitude Altitude
    25.25 deg -76.60 deg 20.00 km
  7. Select the Enter key.
  8. Click OK to confirm your changes and to close the Properties Browser.

Modeling the launch vehicle

Next, model the launch vehicle and its trajectory using a Missile object. While it may seem more intuitive to use a Launch Vehicle object, which models the properties and behavior of a vehicle that follows an ascent trajectory from a launch point to an orbit insertion point, Launch Vehicle objects do not possess the properties that allow them to be used with the EOIR capability. You can, however, use a Launch Vehicle's ephemeris to model the trajectory you want.

Inserting a Launch Vehicle object

Insert a new Launch Vehicle object using the Define Properties method.

  1. Bring the Insert STK Objects tool () to the front.
  2. Insert a Launch Vehicle () object using the Define Properties () method.
  3. Enter 25 m in the Launch Altitude field when the Properties Browser opens.

    4. You will be modeling a vehicle with a 50-meter tall body, and the launch altitude is measured from the model's center point. In order for the launch vehicle's EOIR shape to be positioned correctly, you must adjust this launch altitude accordingly.

  4. Click OK to confirm your change, close the Properties Browser, and propagate the Launch Vehicle object.

Exporting the Launch Vehicle object's ephemeris

The Launch Vehicle object uses the Simple Ascent propagator, which creates an ascent trajectory based on launch and insertion parameters. The trajectory is a simple curve rising vertically from the launch pad that turns over smoothly to insert the launch vehicle into orbit with a zero flight path angle at the insertion point using the specified velocity. The propagator models the motion along the path using a cubic polynomial in time, so that the velocity profile is a quadratic polynomial in time, rising from zero to arrive at the end time with the specified burnout velocity. This propagator is not available for Missile objects, so you must export the Launch Vehicle's ephemeris data using the Export Ephemeris/Attitude tool.

  1. Right-click on LaunchVehicle1 () in the Object Browser.
  2. Select Export Ephemeris/Attutide... in the shortcut menu.
  3. Click Export... next to the Output File field when the Create Data File dialog box opens.
  4. Navigate your scenario folder (for example, C:\Users\<username>\Documents\STK_ODTK 13\EOIR_AirObservation) when the External Type dialog box opens.
  5. Note the File name is set to LaunchVehicle1.e.
  6. Click Save to confirm your selection and to close the External Type dialog box.
  7. Click Close to close the Create Data File dialog box.
  8. Clear the check box for LaunchVehicle1 () in the Object Browser.

    9. You do not need to display it for further analysis.

Inserting a Missile object

Model the launch vehicle with a Missile object. A Missile object typically models the properties and behavior of a vehicle following an elliptical path that begins and ends at the surface of the central body, but you can also use external ephemerides with it to more closely model your needs.

  1. Bring the Insert STK Objects tool () to the front.
  2. Insert a Missile () object using the Insert Default () method.
  3. Rename Missile1 () TestVehicle.

Importing the Launch Vehicle object's ephemeris

The StkExternal propagator enables you to import the ephemeris for a vehicle directly from a file. By importing the ephemeris from LaunchVehicle1, you can model a typical launch from the Kennedy Space Center.

  1. Open TestVehicle's () Properties ().
  2. Select the Basic - Trajectory page when the Properties Browser opens.
  3. Open the Propagator drop-down list.
  4. Select StkExternal.
  5. Click the Filename ellipsis ().
  6. Navigate to your scenario folder (for example, C:\Users\<username>\Documents\STK_ODTK 13\EOIR_AirObservation) when the Select an Ephemeris File dialog box opens.
  7. Select LaunchVehicle1.e.
  8. Click Open to confirm your selection and to close the Select an Ephemeris File dialog box.
  9. Click Apply to confirm your changes and to keep the Properties Browser open.

Building TestVehicle's EOIR shape

Set up the EOIR Shape for the launch vehicle. You can select shapes and specify corresponding dimensions to represent them. This will define what the sensor will see when it targets TestVehicle.

Adding the first component

A Missile object's Basic EOIR Shape properties enable you to define the shape of a particular launch vehicle by stacking geometric components. You will create a generic shape for TestVehicle, which is a cylinder with a cone on top. Start with a simple, cylindrical shape forming the body; components are defined from the bottom up.

  1. Select the Basic – EOIR Shape page.
  2. Ensure Component1 is selected in the Component list.
  3. Open the Shape drop-down list.
  4. Select Cylinder.
  5. Enter the following dimensions for Component1:
    6. Option Value

    Height

    50 m
    Radius 10 m
  6. Leave the Body Temperature set to Static.
  7. Enter 500 K in the Temperature panel.

    8. This temperature is applied the entire shape over the entire EOIR scene time period.

  8. Leave the Material set to Gray Body.

    9. This is the material type that appears on the surface of the entire shape. The Gray Body material has a user-selectable reflectance that is constant across the spectrum. It does not represent any real material, but is useful for setting up test situations.

  9. Click Apply to confirm your changes and to keep the Properties Browser open.

Component stacking orientation

Adding a second component

Now, create a second, conical component to model the launch vehicle's nose cone.

  1. Click Add next to the Component list.
  2. Set the following options for Component2:
    3. Option Value

    Shape

    Cone

    Height

    50 m
    Radius 10 m
    Body Temperature Static
    Temperature 500 K
  3. Click Apply to confirm your changes and to keep the Properties Browser open.

When an object of one material consists of two or more simple geometric shapes, the EOIR capability will approximate each shape as a bounded sphere while estimating the percentage overlap for high-accuracy areas.

Defining TestVehicle's exhaust plume

TestVehicle launches with a three-minute burn. Use the EOIR Stage properties to define the behavior and properties of the burn's exhaust plume. The EOIR capability models the plume as a solid gray body, highly emissive in infrared, utilizing the Planck function and an assigned temperature. The shape is attached to the active (lowest attached) stage. The plume shape automatically adjusts its length and width according to the length and width of the first (lowest) shape element on that stage. The shape consists of a sphere and cone, similar to the shape of an ice cream cone, with the sphere attached to the first (lowest) shape element of the stage and the tip of the cone pointing away from the stage.

  1. Select the Basic – EOIR Stage page.
  2. Note the On Time Delta is set to 0 sec.

    3. This is the point in time at which the plume is turned on, specified in seconds from the start time.

  3. Enter 180 sec in the Off Time Delta field.

    4. This is the point in time at which the plume is shut off, specified in seconds from the start time. The minimum time is 0 sec and the maximum is 86,400 sec (one day).

  4. Click OK to confirm your changes and to close the Properties Browser.

Your launch vehicle has only a single stage. For multi-stage vehicles, you must create one Missile object for each stage.

Modeling the MWIR camera with EOIR

The Electro-Optical Infrared Sensor Performance (EOIR) capability models the detection, tracking, and imaging performance of electro-optical and infrared sensors. You can use the EOIR capability to support concept development, design, field-testing, and operations. The STK software takes this modeling to the big picture by considering electro-optical and infrared performance in conjunction with sensor platform dynamics, communications, and other mission architecture elements to assess integrated performance. The EOIR capability has the ability generate performance metrics such as signal-to-noise ratio and sensor images with both Earth and space in the background.

To create an EOIR scene, you need to specify the EOIR properties for both the Sensor object and the other objects in the scene. You've already modeled the objects in the scene; now, model the sensor.

Inserting a Sensor object

Attach a Sensor object to TestAcft. A Sensor object models the field of view and other properties of a sensing device attached to another STK object.

  1. Bring the Insert STK Objects tool () to the front.
  2. Insert a Sensor () object using the Insert Default () method.
  3. Select TestAcft () when the Select Object dialog box opens.
  4. Click OK to insert the Sensor object and to close the Select Object dialog box.
  5. Rename Sensor1 () MWIR.

Updating the sensor's location

Place the sensor on the nose of the aircraft by updating its Location properties.

  1. Open the MWIR's () Properties ().
  2. Select the Basic – Location page when the Properties Browser opens.
  3. Open the Location Type drop-down list.
  4. Select Fixed.

    5. With a Fixed Location type, the location of the sensor is defined using a fixed displacement vector with respect to the parent object’s body frame.

  5. Ensure Cartesian is selected in for the Type in the Fixed Location panel.
  6. Set the following Cartesian coordinates:
    7. Option Value
    X 0.018 km
    Y 0 km
    Z 0 km
  7. Click Apply to confirm your changes and to keep the Properties Browser open.

Targeting the sensor to TestVehicle

The camera tracks and follows TestVehicle. Update the sensor's Pointing properties to set the parameters that determine how it is aimed.

  1. Select the Basic – Pointing page
  2. Open the Pointing Type drop-down list.
  3. Select Targeted.

    4. The Targeted pointing type causes the sensor to point to other objects in the scenario.

  4. Select TestVehicle () in the Available Targets list.
  5. Move () TestVehicle () to the Assigned Targets list.
  6. Click Apply to confirm your changes and to keep the Properties Browser open.

Selecting the EOIR sensor type

Select the EOIR sensor type on the sensor's Definition page. The EOIR sensor type is used to model electro-optical and infrared sensors an supports up to 36 bands per sensor. For this analysis, you'll use only a single band.

  1. Select the Basic - Definition page.
  2. Open the Sensor Type drop-down list.
  3. Select EOIR.
  4. Double-click in the Band name field.
  5. Rename the band MWIR.
  6. Click Apply to confirm your changes and to keep the Properties Browser open.

Setting the sensor's spatial properties

By default, an EOIR sensor is set up with a single band. Select the Spatial tab on the Definition page to specify the spatial properties for each band. The default input setting for the band is Field-of-View and Number of Pixels. Update the sensor's field of view to narrow its focus.

  1. Select the Spatial tab.
  2. Leave Field-of-View and Number of Pixels selected for the Input method.
  3. Enter the following values in the Field of View panel
    4. Option Value
    Vertical Half Angle 0.02 deg
    Horizontal Half Angle 0.02 deg

    The EOIR capability uses these half angles to determine the full angular extent of the sensor field of view (FOV).

  4. Click Apply to confirm your changes and to keep the Properties Browser open.

Setting the sensor's spectral properties

Specify the sensor's spectral properties to model the spectral response of the MWIR thermal imaging camera, which operates in the 3.0 to 5.5-micrometer wavelength range.

  1. Select the Spectral tab.
  2. Enter the following values in the Spectral Band Edge Wavelengths panel:

    3. You must set the High value first.

    Option Value
    High 5.50
    Low 3.00
  3. Leave the Number of Intervals as the default.

    4. The internal sensor model samples your spectral band using the number of intervals you define. The more intervals you have, the higher the accuracy of the analysis. However, more intervals mean longer computation time.

  4. Leave the Spectral Shape set to the Use Optical and Radiometric Response option.

    5. This leaves the spectral shape to the individual optical transmission and quantum efficiency spectral characteristics.

  5. Click Apply to confirm your changes and to keep the Properties Browser open.

Setting the sensor's optical properties

Next, specify the sensor's optical properties by choosing which two optical parameters will serve as the inputs used to calculate a third parameter.

  1. Select the Optical tab.
  2. Open the Input drop-down list.
  3. Select Focal Length and Entrance Pupil Diameter.
  4. Enter the following input parameters, which are measured in centimeters:
    5. Option Value
    Effective Focal Length 415
    Entrance Pupil Diameter 100
  5. Select Negligible Aberrations.

    6. The EOIR capability models aberrations based on a root-mean-square wavefront error. The Negligible Aberrations setting introduces a 7% wave front error.

  6. Click Apply to confirm your changes and to keep the Properties Browser open.

Setting the sensor's radiometric properties

The sensor's radiometric properties define its noise floor and its saturation ceiling.

  1. Select the Radiometric tab.
  2. Leave the Input set to High Level.

    3. With high-level radiometric parameters, you can populate and edit sensor performance data with measurements from an actual sensor or estimates for a sensor being developed.

  3. Leave the Sensitivity values set at their default values.

    4. When preparing to take measurements with a sensor model, you specify an integration time. This is the time interval over which a radiant signal is collected before generating an image. The longer the time, the more photons that get collected. This field is equivalent to the "exposure time" setting on an analog film camera. You can also define a set of points that relate Integration (Exposure) Time to NEI/SEI (noise equivalent irradiance / saturation equivalent irradiance). The STK application linearly interpolates between the points to get correct NEI/SEI for the integration time you set.

  4. Click OK to confirm your changes and to close the Properties Browser.

Viewing the setup in the 3D Graphics window

Take a look at your setup in the 3D Graphics window to gain situational awareness.

  1. Right-click on TestVehicle () in the Object Browser.
  2. Select Zoom To in the shortcut menu.
  3. Bring the 3D Graphics window to the front.
  4. Use your mouse to zoom out and get a good view of the relationship between the launch site, TestVehicle, TestAcft, and the sensor field of view.

Setting the animation time

TestVehicle will launch from the ground with a three-minute burn duration. To make it easier to see, move forward in the scenario by a few seconds.

  1. Click Decrease Time Step () on the Animation toolbar until the Time Step is set to 1.00 sec.
  2. Click Start () on the Animation toolbar.
  3. Watch as TestVehicle lifts off from the launch pad and is tracked by the MWIR sensor.
  4. Click Reset () on the Animation toolbar when finished.
  5. Click Step Forward () on the Animation toolbar to move ahead to three seconds after TestVehicle's burn starts.

Opening the EOIR toolbar

To get started using the EOIR capability with your sensor, you must first display the EOIR toolbar. You can use the EOIR toolbar to access the EOIR configuration and EOIR sensor scene for a particular sensor.

  1. Select View in the Menu Bar.
  2. Select Toolbars in the View menu.
  3. Select EOIR in the Toolbar submenu to show the EOIR toolbar ().

Updating the EOIR configuration

To see TestVehicle in the EOIR sensor scene, you must first add it as a target in the EOIR configuration. When you include an object as a target in the EOIR configuration, its EOIR properties are taken into account.

  1. Click EOIR Configuration... () on the EOIR toolbar.
  2. Select Missile/TestVehicle () in the Available STK Objects list when the EOIR Configuration dialog box opens.

    3. All central bodies and objects, except for the source sensor, that are part of the EOIR Configuration are listed in the Available STK Objects list.

  3. Move () Missile/TestVehicle () to the Selected Targets list.
  4. Click OK to confirm your selection and to close the EOIR Configuration dialog box.

An EOIR sensor will take images of objects in the Selected Targets list that are sufficiently bright, either in reflected light or from self-radiance, at wavelengths that the sensor can detect.

Generating an EOIR sensor scene

Now you are ready to generate an EOIR sensor scene. There are two sensor scene images generated: an internal image passed to a sensor model and a displayed image (or sensor scene). The displayed image is different from the internal image in that the dynamic range is compressed to fit the display’s RGB capabilities, it has automatic gain control and brightness/contrast settings, and it has pixel value mapping for false color display. The EOIR line of sight and field of view are synchronized to the STK Sensor object.

Generating the sensor scene from the EOIR toolbar

To generate an input scene for the selected sensor, use the buttons on the EOIR toolbar.

  1. Select MWIR () in the Object Browser.
  2. Click EOIR Sensor Scene... () on the EOIR toolbar.

TestVehicle and exhaust plume

The Sensor Scene Generator generates an image in the EOIR Sensor Scene window that represents the sensor's output based on material optical properties, object shape models, and thermal models of the objects in the scene. The scene accurately portray sensor images for the processing level selected. By default, it generates an image with a gray scale color map.

Adjusting and reviewing the simulated scene

Open the EOIR Scene Visual Details dialog box, which enables you to display, adjust, and save to a file the visual details for the selected scene.

  1. Right-click on the sensor scene.
  2. Select Details... in the shortcut menu.
  3. Move the EOIR Scene Visual Details dialog box when it opens so that it's not sitting on top of the sensor scene.
  4. Click on TestVehicle's body and on its exhaust plume in the EOIR sensor scene.

    5. Note that, in addition to the name of the Missile object (TestVehicle), other information about the vehicle is displayed in the Scene Pick Information panel in the EOIR Scene Visual Details dialog box, including the distance to it in kilometers, the azimuth and elevation to the target, and the thermal model temperature and material type of the surface location. You can see that both the body and exhaust plume are defined as Gray Body materials with the temperatures specified in TestVehicle's EOIR Shape and Stage properties, respectively.

  5. Select the Fine option in the Scene Detail panel.
  6. Select the BGRY option in the Color Map panel.

    7. Selecting a color map enables various "false color" mappings of the display. EOIR uses false color to bring out details in the image data that are often lost when displayed on a monitor with less resolution than the EOIR sensor. For instance, a typical monitor can display only 256 levels of grayscale, whereas an EOIR sensor might have 4096 levels of grayscale resolution. Color mapping is only for visual effect and does not change any of the internal data values. This can be particularly useful when viewing materials of differing temperatures through an infrared sensor.

  7. Click OK to confirm your changes and to close the EOIR Scene Visual Details dialog box.
  8. Keep the EOIR Sensor Scene window open.

Examining an event

TestVehicle executes a burn for the first three minutes of its flight. View what the sensor is seeing the moments before and after the burn ends.

  1. Manually change the Current Scenario time in the Animation toolbar so that it is two minutes and 59 seconds after your scenario start time (for example, 16:02:59.000).
  2. Select the Enter key.
  3. Bring the EOIR Sensor Scene window to the front.
  4. Examine your EOIR sensor scene.

    5. TestVehicle and exhaust plume BGRY COLOR MAP

    You should see TestVehicle and its plume. Note the radiant glow from the heat produced by the plume.

  5. Click Step Forward () to move ahead to one second after the end of TestVehicle's burn.
  6. Examine your EOIR sensor scene and note the changes.

TestVehicle exhaust plume off

Note that the test vehicle continues to emit a radiant glow even after the burn stops, owing to the temperature of the body components. Also note that the background has changed. This is because your sensor scene has Automatic Gain Control (AGC) enabled. With this selection, the EOIR capability automatically calculates brightness and contrast such that the brightest scene detail fits within the brightness resolution of the monitor. At this moment in time, there is no burn, so the leveling for the noise in your synthetic scene is also updated. Your image may look different, as the rendering of the scene is based on the signal-to-noise ratio of the launch vehicle.

Adjusting TestVehicle's EOIR properties

Now that you’ve taken a look at TestVehicle, see how the system is affected when the launch vehicle's EOIR properties change.

Updating a component's temperature

Increase the temperature of one of TestVehicle's components to see how that changes your EOIR sensor scene.

  1. Open TestVehicle's () Properties ().
  2. Select the Basic - EOIR Shape page when the Properties Browser opens.
  3. Enter 1000 K in Component1's Temperature field.
  4. Click Apply to confirm your change and to keep the Properties Browser open.
  5. Bring the EOIR Sensor Scene window to the front.
  6. Review the changes.

differing EOIR component temperatures

The sensor scene automatically regenerates based on the property updates when it is open. Note that TestVehicle's body is now glowing much brighter than its nose cone, as it is radiating more thermal energy.

Changing a component's surface material

The EOIR capability models material types for aircraft, missiles, ships, ground vehicles, and satellites. The source for these material property models is NASA Reference Publication 1121, Apr 1984, "Solar Absorptance and Thermal Emittance of Some Common Spacecraft Thermal-Control Coatings (PDF)". The STK application uses thermal models plus material emissivity to calculate each object's self-radiance via the Planck function. Change the body's surface material to see how that affects your sensor scene.

  1. Return to TestVehicle's () Properties ().
  2. Enter 500 K in Component1's Temperature field.
  3. Open the Material drop-down list.
  4. Select Aluminum MLI.
  5. Click Apply to confirm your changes and to keep the Properties Browser open.
  6. Bring the EOIR Sensor Scene window to the front.
  7. Review the changes.

differing EOIR material types

In spite of the body temperature being the same between the two components, the body's aluminum multilayer insulation surface is radiating less heat.

Resetting the component's surface material

Reset the component's surface material back to Gray Body.

  1. Return to TestVehicle's () Properties ().
  2. Open the Material drop-down list.
  3. Select Gray Body.
  4. Click OK to confirm your changes and to close the Properties Browser.
  5. Keep the EOIR Sensor Scene window open.

Generating a custom EOIR graph

The EOIR capability does more than simulate scenes created by an EOIR sensor. Its internal sensor model can also calculate metrics a sensor would receive from a target's signal. Use the EOIR data providers included with the capability to create a graph at the effective target radiance, which measures the Power Flux Intensity. This is the average apparent radiance at the sensor aperture from a target object.

Creating a custom graph style

First, create a new graph style called EOIR_TargetRadiance.

  1. Right-click on MWIR () in the Object Browser.
  2. Select Report & Graph Manager... in the shortcut menu ().
  3. Select the My Styles () folder in the Styles panel when the Report & Graph Manager opens.
  4. Click Create new graph style () on the Styles toolbar.
  5. Name the graph style EOIR_TargetRadiance.
  6. Select the Enter key to rename the graph style and open the Properties Browser.

Selecting the graph's data providers

Use the EOIR Sensor To Target Metrics data provider and the In-band target radiance data provider element for your graph.

  1. Expand () the EOIR Sensor To Target Metrics () data provider in the Data Provider list when the Properties Browser opens.

    2. These are time dependent metrics for a unique EOIR Sensor-Band / Target pairing.

  2. Select In-band target radiance () in the Data Provider list.
  3. Move () the In-band target radiance () data provider element to the Y Axis list.
  4. Click OK to confirm your change and to close the Properties Browser.

Setting the graph's Time properties

Set the graph's Time properties so the data is reported only over the course of TestVehicle's flight.

  1. Select the Specify Time Properties option in the Time Properties panel.
  2. Open () the Start and Stop times drop-down menu.
  3. Select Interval Component....
  4. Select TestVehicle () in the Objects list when the Select Time Interval dialog box opens.
  5. Select EphemerisTimeSpan (), located in the Installed Components () folder, in the Intervals for: TestVehicle list.
  6. Click OK to confirm your selection and to close the Select Time Interval dialog box.

Generating the Sensor to Target Metrics graph

Now, generate the EOIR Target Radiance graph over the duration of the burn.

  1. Select the Use step size/ time bound option.
  2. Enter 10 sec in the Step size field.
  3. Select Sensor to Target Metrics () in the Styles list.
  4. Click Generate....

    5. Be patient. It may take the STK application a while to generate the graph.

  5. Review the graph.

    6. TestVehicle exhaust plume off

    Note the drop in target radiance when TestVehicle's burn ends around the three-minute mark.

  6. Hover your mouse over the radiance values after the burn has ended to examine their levels.
  7. Close your Sensor to Target Metrics graph when finished.
  8. Click Close to close the Report & Graph Manager.
  9. Save () your scenario.

Creating a video from saved EOIR images

You can create a video from your EOIR images using free or professional video editing software. Configure your scenario to export EOIR frames at an appropriate format and frame rate.

This is an optional section for those who wish to learn how to create a video for EOIR sensor scenes if you do not want to create a video, skip to the Saving your work section.

Updating the scenario’s Basic Time properties

For the purposes of this tutorial, you want to make a ten-second movie, beginning five seconds before and after the burn ends. Update the scenario's Animation properties to set the Scenario's Animation Time and Step Size for your movie.

  1. Open EOIR_AirObservation's () Properties ().
  2. Select the Basic - Time page when the Properties Browser opens.
  3. Clear the Use Analysis Start Time check box in the Animation panel.
  4. Set the Start time to five seconds before the burn ends, for example, [date] 16:02:55.000.
  5. Select the Stop at Time check box.
  6. Clear the Use Analysis Stop Time check box.
  7. Set the Start time to fives seconds after the burn ends, for example, [date] 16:03:05.000.
  8. Enter 0.03 seconds in the Step Size field.

    9. This is equivalent to approximately 30 frames per second (fps), a standard digital video content frame rate.

  9. Click OK to confirm your changes and to close the Properties Browser.
  10. Click Reset () on the Animation toolbar.

Preparing your sensor scene

The EOIR capability processes the raw sensor data or a scene bitmap (*.bmp) based on the selected level (radiometric input, geometric input, or sensor output) for each animation time step.

  1. Right-click on the sensor scene in the EOIR Sensor Scene window.
  2. Select Details... in the shortcut menu.
  3. Move the EOIR Scene Visual Details dialog box when it opens so that it's not sitting on top of the sensor scene, if needed.
  4. Select the Scene Bitmap check box in the Automatic File Output panel.

Setting the storage location

Images are saved as BMP files in the specified folder location.

  1. Click the Storage Location ellipsis ().
  2. Right-click in the folder and file browser when the storage location dialog box opens.
  3. Ensure you are in your scenario folder (for example, C:\Users\<username>\Documents\STK_ODTK 13\EOIR_AirObservation).
  4. Select New in the shortcut menu.
  5. Select Folder in the New submenu.
  6. Name your folder EOIR_Movie.
  7. Select the Enter key.
  8. Ensure EOIR_Movie is noted in the Folder field.
  9. Click Select Folder to confirm your selection and to close the storage location dialog box.

    10. Note the Storage Location now points to your EOIR_Movie subfolder.

  10. Click Apply to confirm your changes and to keep the EOIR Scene Visual Details dialog box open.

Creating the still frames

With your animation time and your output configured, capture your still frames.

  1. Click Start () on the Animation toolbar.
  2. Watch as the sensor scene animates in the EOIR Sensor Scene window.
  3. Return to the EOIR Scene Visual Details dialog box when the scenario has finished animating.
  4. Clear the Scene Bitmap check box in the Animation panel.

    5. You don't want to capture every frame if you want to continue exploring your scenario.

  5. Click OK to confirm your changes and to close the EOIR Scene Visual Details dialog box.

Reviewing the results

When creating automatic file output for each animation step, the EOIR capability creates a new file with a file name that contains the corresponding time in epoch seconds.

  1. Open Windows File Explorer.
  2. Navigate to the location of your saved stills (for example, C:\Users\<username>\Documents\STK_ODTK 13\EOIR_AirObservation\EOIR_Movie).
  3. Look at your stills.

You can see you have over 300 stills for your short movie. Each is named with the name of the sensor and the time step it represents. This makes it easy to put them in sequential order.

Creating a new video project with the OpenShot Video Editor

You can use any number of video editing software choices to create your video, such as Adobe Premier or Microsoft ClipChamp. The steps that follow use the OpenShot Video Editor, a free and open-source video editor for Linux, Mac, and Windows. While the precise steps may be different in other editors, the concept is the same.

  1. Open the OpenShot Video Editor application.
  2. Click New Project on the Toolbar.
  3. Click Import Files.
  4. Navigate to the location of your saved stills (for example, C:\Users\<username>\Documents\STK_ODTK 13\EOIR_AirObservation\EOIR_Movie) when the Import Files... dialog box opens.
  5. Multi-select all 300+ stills in the folder.
  6. Click Open to confirm your selection and to close the Import Files... dialog box.

Be patient. This could take a while.

Building your video

With your stills added to your project's files, add them to the project Timeline.

  1. Multi-select all the images in the Project Files tab.
  2. Right-click on one of the images.
  3. Select Add to Timeline in the shortcut menu.
  4. Enter 0.03 in the Image Length (seconds) field in the Timeline Location panel when the Add To Timeline dialog box opens.

    5. Set this value based on the time step the images were taken in the scenario.

  5. Note the Total Length of your movie is calculated as 00:00:10.02 seconds.

    6. The Track has an initial time of 00:00:00,01.

  6. Click OK to confirm your changes and to close the Add To Timeline dialog box.

    7. Be patient. This may take a while. The images should automatically be added to the timeline based on their files names, which, as you recall, reflect the time steps you specified.

  7. Click Play in the Video Preview panel to ensure your video looks correct.

Exporting your video

With your frames put in order and displaying for an appropriate amount of time, export a video out of your project.

  1. Click Export Video on the toolbar.
  2. Enter EOIR_Movie in the File Name field when the Export Video dialog box opens.
  3. Click Browse... next to the Folder Path field.
  4. Set the Folder Path to where you saved your stills (for example, C:\Users\<username>\Documents\STK_ODTK 13\EOIR_AirObservation\EOIR_Movie) when the Choose a Folder... dialog box opens.
  5. Click Select Folder to confirm your selection and to close the Choose a Folder... dialog box.
  6. Ensure the Target is MP4 (h.264).
  7. Ensure the Video Profile is HD 720p 30 fps (1280x720).
  8. Click Export Video.
  9. Click Done when the process is finished to close the Export Video dialog box.

Viewing your finished movie

Take a look at your finished movie.

  1. Return to Windows File Explorer.
  2. Open your finished MP4 movie with the video player of your choice.

  3. Watch as TestVehicle's burn stops in real time and the sensor gain levels change, just as you might see in a real EOIR sensor feed.
  4. Close the video player when you are finished.

If your movie does not look right — dropped frames, uneven animation, and so on, try exporting the video with different settings. For example, try exporting with a different video profile with a lower frame rate (such as 25 fps).

Resetting the scenario's Animation properties

Reset your scenario's animation time for the full analysis period.

  1. Close the OpenShot Video Editor when you are finished without saving your project.
  2. Return to the STK application.
  3. Open EOIR_AirObservation's () Properties ().
  4. Select the Basic - Time page when the Properties Browser opens.
  5. Select the Use Analysis Start Time check box in the Animation panel.
  6. Select the Use Analysis Stop Time check box.
  7. Click OK to confirm your changes and to close the Properties Browser.

Saving your work

Close out your scenario and save your work.

  1. Close () the EOIR Sensor Scene window.
  2. Close any open reports, properties, and the Report & Graph Manager.
  3. Save () your work.

Summary

In this tutorial, you learned how to build and analyze an observation system on an aircraft. You tracked a launch vehicle using an EOIR sensor to see what a camera on the aircraft would see and even generated data from the sensor scene and from available EOIR data providers. This is especially useful information because you can see from your radiance graph that the signal is high during the initial burn, but drops once the burn completes. Your ability to track and detect objects like space launch vehicles depends on the sensors you design and build for your missions.

On your own

Expand your mission. In this lesson, you modeled a single sensor and a single band. The EOIR capability gives you the flexibility to model multiple sensors and bands for your mission. Try it out and see how your results may differ when looking at different parts of the spectrum.