Sample OpModes

The intent of this tutorial is to describe the available camera controls, allowing programmers to develop their own solutions guided by the SDK API (Javadoc).

Rather than reproduce sample code here, this page points to the OpModes in the FtcRobotController repository, which are maintained alongside the SDK and updated each season. The same samples are available in Android Studio and OnBot Java, under FtcRobotController/external/samples.

Exposure and Gain

ConceptAprilTagOptimizeExposure.java is the SDK’s camera controls sample. It builds a VisionPortal with an AprilTag Processor, then asks the Portal for its control objects:

ExposureControl myExposureControl = visionPortal.getCameraControl(ExposureControl.class);
GainControl myGainControl = visionPortal.getCameraControl(GainControl.class);

The gamepad bumpers and triggers raise and lower exposure and gain, while telemetry reports the tags currently detected. Its goal is to find the smallest (shortest) exposure that still gives reliable detection, since a short exposure reduces motion blur while the robot is driving. Start with the minimum exposure and maximum gain, then slowly increase the exposure until the tag is detected reliably from the likely operational distance.

The best way to run this optimization is to watch the camera preview while changing the exposure and gain, as described in Observing Controls.

That sample is also a reasonable starting point for the other controls described in this tutorial. FocusControl, WhiteBalanceControl and PtzControl are all requested from the Portal in exactly the same way.

Focus, White Balance and PTZ

The SDK does not ship a sample for these three controls. These Blocks test OpModes cover them, and can be built in Java by clicking Export to Java in the Blocks editing interface:

Another test OpMode is posted here and shown below. It uses 7 of the 11 Exposure Control Blocks, omitting 4 unlikely to be used.

The gamepad can raise and lower the webcam’s Exposure value, while observing the live effect on previews and processor results. This allows a team to quickly find their preferred Exposure value in that environment.