How to keep an EOIR Sensor from Rendering When There are No Objects to See?

If you are animating through a scenario with an EOIR sensor and have the synthetic scene displayed, the animation lags due to the synthetic scene rendering with each time step.  This is acceptable when you have objects of interest in the sensor field of view.  But if there are no objects worth rendering, the animation is being slowed down for no reason.  If you are using a sensor with the pointing type set to Targeted, then if the sensor does not have access to the target object selected, the EOIR scene will not render.  However, if your EOIR sensor is a fixed sensor, it is not that simple.  You can still limit the times that the EOIR sensor renders by using these steps:

1. Create a sensor called "FixedSensor" with the field of view and a fixed pointing orientation you desire. The sensor boresight vector will be used to create a “dummy” object to be used in targeting the eventual EOIR sensor.

2. Calculate access between this sensor and the object that you want to track with the EOIR sensor. You will use these access times as constraints later.

Report on the FixedSensor Boresight Vector

1. Open the Report and Graph Manager.

2. Select FixedSensor as the object and create a new report.

3. Name the report "Boresight Coordinates".

4. Open the Boresight Coordinates report properties and select the time, x, y, and z data sets from the Vector Choose Axes data provider.

5. Generate the report and select the base object of the FixedSensor’s body frame as the axes.

6. Copy the coordinates of this report into an ephemeris file and format it appropriately.

Insert a New Aircraft

1. Insert a new aircraft from the ephemeris file created in step 3 and name it "dummy".

2. In the dummy properties under Constraints > Temporal, enable the Use box for intervals.

3. Click Edit list to remove anything existing.

4. Click Import and select the access intervals for the access calculated above. This will limit the times that the dummy object “exists” for limiting when the EOIR sensor renders.

Duplicate FixedSensor

1. Duplicate the FixedSensor.

2. Change the type to EOIR.

3. Change the pointing to Targeted and select the dummy aircraft as the assigned target.

Now the EOIR sensor still points in the fixed direction that is desired, but it is limited by the temporal constraints put on the dummy object. There are many variations in the EOIR sensor pointing and temporal constraints that can be used, but this is one example.

Note:  If you are using a facility as the base object for the EOIR sensor, using the "targeted" pointing type will result in a synthetic scene that is not oriented correctly. There is another FAQ on this (see Why is My EOIR Synthetic Scene Rotated Incorrectly?) where you use the Targeted Along Vector pointing type. However, you cannot set the times when a sensor renders or not with this target type. A solution is to use an aircraft object that is on the ground as the base object. The synthetic scene orients correctly on air objects (aircraft, satellites, missiles), so you do not need to use the Targeted Along Vector solution.