Obscuration Tool

The Obscuration tool enables you to determine when a sensor's field of view is obscured by one or more objects, including the sensor's parent object. You can view sensor obscuration in the Obscuration View window and generate reports and graphs of obscuration data.

You can use the Obscuration tool with any sensor attached to a vehicle. To access the Obscuration tool for a particular sensor, highlight the sensor in the Object Browser and select Obscuration... from the Sensor menu.

The Obscuration tool contains:

  • Obscuration View window. This window enables you to see the changes in the position of the object model during animation. Use the Animation toolbar to set your scenario in motion. Use the button on the Default toolbar to access the Area Panel window.

    The viewer direction is looking down the sensor's boresight. Potentially obscuring objects display in black against a white background. Unobscured portions of the sensor's field of view display in yellow, while the obscured portions display in blue.

    Using capabilities made available in the Vertex Offset page of the sensor's 3D Graphics properties, you should bring the vertex to a point "behind" the sensor, so that the sensor is just contained within the projection. A minimal amount of trial and error with the Sensor Radius field should suffice to approximate the desired view. You can also take advantage of any attach points defined in the sensor's model file.

  • Obscuration window. This window enables you to define the view in the view window and set data reporting options.

You cannot use the Obscuration tool on any model that contains the FaceEmissionColor parameter.

Obscuring Objects

The Obscuring Objects list contains central bodies and scenario objects that are candidates for obscuring the sensor's field of view. Stars are excluded from the list. Any or all of the available objects can be selected for analysis.

Select All button. Selects all items in the Obscuring Objects list.

Deselect All button.Clears all items in the Obscuring Objects list.

You can also use the mouse to select individual items in the Obscuring Objects list.

Data

The Obscuration tool computes obscuration over time by animating the scenario and periodically counting the pixels corresponding to obscured and unobscured portions of the field of view.

Interval/Start/Stop Times. The time interval or start and stop times during which obscuration data is reported. The Start Time and Stop Time must both be within an availability interval for the sensor and any obscuring objects. If you do not set these parameters, they default to the first availability interval of the sensor. For more information on the options available for time intervals and start and stop times, see Time Options.

Time Step. The time step used to separate data points.

Compute button. Click to calculate obscuration over the specified start and stop times. If you have already computed obscuration for this satellite, STK displays a window that enables you to choose to delete existing data or cancel the Compute.

Delete Data button. Deletes existing sensor obscuration data so that computer memory is restored once analysis is complete.

Data Reporting

Once you compute the sensor obscuration data, you can display the results in report or graph form.

Report. For each time step, displays the percentage of the sensor's field of view obscured by the selected obscuring objects and the percentage unobscured. The report also includes the approximate quantities of pixels corresponding to the obscured and unobscured portions of the field of view.

Graph. Plots the percentage of the field of view obscured over time.

The Obscuration tool requires the value of the half angle in a sensor's field of view (FOV) to be 79.5 or lower.

Rendering

Do not render normal 3D windows while computing. Select to stop rendering normal 3D Graphics windows when the tool is computing data. This option can improve the speed of the computations.