Vuforia and OpenCV Beacon Color Detection

Vuforia and OpenCV are image processing libraries. Vuforia is by PTC and is built in to the latest version of the FTC app. It has high-level functions for tracking objects and augmented reality. It is very useful for finding the position of the beacon target images.

OpenCV is an open source library that is more low-level, and because of this it is possible to write the procedures yourself and optimize them for better performance.

Before you can use this example, you have to:

• Set up OpenCV. A guide is available on our website at http://www.gearbox4h.org/opencv/
• Create a Vuforia developer account and get a license key from https://developer.vuforia.com/license-manager

This example uses EVLib functionality to:

• Initialize Vuforia
• Find the "Gears" beacon target image (this is controlled by the TeamColor.RED input)
• Crop the beacon out of the frame based on the target image location
• Find the beacon's color

sample/v3/SampleVuforiaOp.java

package org.firstinspires.ftc.teamcode.sample.v3;

import com.google.common.collect.ImmutableList;
import com.qualcomm.robotcore.eventloop.opmode.Autonomous;

import org.firstinspires.ftc.teamcode.R;

import ftc.electronvolts.statemachine.EndConditions;
import ftc.electronvolts.statemachine.StateMachine;
import ftc.electronvolts.statemachine.StateMachineBuilder;
import ftc.electronvolts.statemachine.StateName;
import ftc.electronvolts.util.BasicResultReceiver;
import ftc.electronvolts.util.InputExtractor;
import ftc.electronvolts.util.ResultReceiver;
import ftc.electronvolts.util.TeamColor;
import ftc.electronvolts.util.files.Logger;
import ftc.electronvolts.util.units.Time;
import ftc.evlib.driverstation.Telem;
import ftc.evlib.hardware.config.RobotCfg;
import ftc.evlib.opmodes.AbstractAutoOp;
import ftc.evlib.statemachine.EVStates;
import ftc.evlib.vision.framegrabber.VuforiaFrameFeeder;
import ftc.evlib.vision.processors.BeaconColorResult;

/**
 * This file was made by the electronVolts, FTC team 7393
 * Date Created: 12/15/16
 */
@Autonomous(name = "SampleVuforiaOp V3")
public class SampleVuforiaOp extends AbstractAutoOp<RobotCfg> {
    //get a key (for free) and paste it below by creating an account at https://developer.vuforia.com/license-manager
    private static final String LICENSE_KEY = "";

    private static final int FRAME_SIZE = 16;
//    private static final int FRAME_SIZE = 8;
//    private static final int FRAME_SIZE = 64;

    private static final int FRAME_WIDTH = 3 * FRAME_SIZE;
    private static final int FRAME_HEIGHT = 4 * FRAME_SIZE;
//    private static final int FRAME_WIDTH = 11 * FRAME_SIZE;
//    private static final int FRAME_HEIGHT = 9 * FRAME_SIZE;

    private enum S implements StateName {
        WAIT_FOR_VUFORIA_INIT,
        FIND_BEACON_COLOR,
        DISPLAY,
        UNKNOWN_BEACON_COLOR,
        BEACON_COLOR_TIMEOUT
    }

    private ResultReceiver<VuforiaFrameFeeder> vuforiaReceiver;
    private ResultReceiver<BeaconColorResult> beaconColorResult;

    @Override
    public StateMachine buildStates() {
        vuforiaReceiver = VuforiaFrameFeeder.initInNewThread(LICENSE_KEY, R.id.cameraMonitorViewId, FRAME_WIDTH, FRAME_HEIGHT);

        StateMachineBuilder b = new StateMachineBuilder(S.WAIT_FOR_VUFORIA_INIT);
        beaconColorResult = new BasicResultReceiver<>();

        b.addEmpty(S.WAIT_FOR_VUFORIA_INIT, b.ts(EndConditions.receiverReady(vuforiaReceiver), S.FIND_BEACON_COLOR));
        b.add(EVStates.findBeaconColorState(S.FIND_BEACON_COLOR, S.DISPLAY, S.UNKNOWN_BEACON_COLOR, S.BEACON_COLOR_TIMEOUT, Time.fromSeconds(10), vuforiaReceiver, beaconColorResult, TeamColor.RED, 4, true));

        b.add(EVStates.displayBeaconColorResult(S.DISPLAY, beaconColorResult));
        b.add(EVStates.displayBeaconColorResult(S.UNKNOWN_BEACON_COLOR, beaconColorResult));
        b.add(EVStates.displayBeaconColorResult(S.BEACON_COLOR_TIMEOUT, beaconColorResult));

        return b.build();
    }

    @Override
    protected RobotCfg createRobotCfg() {
        return new RobotCfg(hardwareMap) {
            @Override
            public void act() {

            }

            @Override
            public void stop() {

            }
        };
    }

    @Override
    protected Logger createLogger() {
        //it will save logs in /FTC/logs/vuforiaOp[....].csv on the robot controller phone
        return new Logger("vuforiaOp", ".csv", ImmutableList.of(
                //each one of these is a column in the log file
                new Logger.Column("state", new InputExtractor<StateName>() {
                    @Override
                    public StateName getValue() {
                        return stateMachine.getCurrentStateName();
                    }
                }),
                new Logger.Column("beaconColor", new InputExtractor<BeaconColorResult>() {
                    @Override
                    public BeaconColorResult getValue() {
                        return beaconColorResult.getValue();
                    }
                })
        ));
    }

    @Override
    protected void setup_act() {
        Telem.displayVuforiaReadiness(vuforiaReceiver);
    }

    @Override
    protected void go() {

    }

    @Override
    protected void act() {
        telemetry.addData("state", stateMachine.getCurrentStateName());
        Telem.displayVuforiaReadiness(vuforiaReceiver);
    }

    @Override
    protected void end() {

    }
}

This concludes the tutorial for now. Check back later for more updates and sample code, or check out the Features page for other things you can do with EVLib.