AlphaBit - OpenML

AprilTag Detection - Getting Started

AprilTag Beginner Flow

This is the step-by-step implementation path for AprilTag in Decode. The goal is to make pattern detection and pose correction reproducible for beginner FTC teams.

Step 1

Mount and Verify the Webcam

Use hardware map name AlphaBit_Webcam.

Lock camera mount mechanically so pitch/yaw do not shift during impacts.

Set the camera pose offsets in code only after physical mount is final.

Webcam setup step 0 — Initial webcam setup reference.

Webcam setup step 1 — Verify orientation and stable FOV.

Step 2

Initialize AprilTagProcessor and VisionPortal

Use the same pipeline style as drive/ComputerVision/AprilTagIdentification.java:

aprilTagProcessor = new AprilTagProcessor.Builder()
    .setDrawTagID(true)
    .setDrawTagOutline(true)
    .setDrawAxes(true)
    .setDrawCubeProjection(true)
    .setOutputUnits(DistanceUnit.INCH, AngleUnit.DEGREES)
    .setCameraPose(cameraPosition, cameraOrientation)
    .build();

VisionPortal.Builder builder = new VisionPortal.Builder();
builder.setCamera(hwdmap.get(WebcamName.class, "AlphaBit_Webcam"));
builder.setCameraResolution(new Size(640, 480));
builder.addProcessor(aprilTagProcessor);
visionPortal = builder.build();

Step 3

Implement Two ID Groups

Pattern IDs for game logic: 21 / 22 / 23.

Localization IDs for pose refresh: 20 / 24.

Keep these groups separate in code so your autonomous decisions remain predictable.

Step 4

Read Tags During Init and Runtime

During opModeInInit(), lock pattern ID before match start.

During runtime, call pose read only when your safety gates allow correction.

Push X/Y/bearing telemetry to DS for quick confidence checks.

Step 5

Validate Under Match Lighting

Test near bright and dark field zones; don't validate only in pit lighting.

Verify camera can still detect IDs after quick turns and hard braking.

If detections flicker, reduce trust windows and increase stationary-only corrections.

Never hard-reset pose while robot is rotating aggressively.

Open AprilTag Implementation for a full class-level template and integration snippets.

Support -> Discord

Choose Language / Alege Limba

AlphaBit AI Assistant