Using VisionPortal within OpModes

We'll start with a pretty basic example that uses VisionPortal to run the the bundled AprilTagProcessor and explain line by line:

import com.qualcomm.robotcore.eventloop.opmode.Disabled;
import com.qualcomm.robotcore.eventloop.opmode.LinearOpMode;
import com.qualcomm.robotcore.eventloop.opmode.TeleOp;
import org.firstinspires.ftc.robotcore.external.hardware.camera.WebcamName;
import org.firstinspires.ftc.vision.VisionPortal;
import org.firstinspires.ftc.vision.apriltag.AprilTagDetection;
import org.firstinspires.ftc.vision.apriltag.AprilTagProcessor;

@Autonomous(name = "Example VisionPortal OpMode")
public class ExampleVisionPortalOpMode extends LinearOpMode {

    /**
     * The variable to store our instance of the AprilTag processor.
     */
    private AprilTagProcessor aprilTag;

    /**
     * The variable to store our instance of the vision portal.
     */
    private VisionPortal visionPortal;

    @Override
    public void runOpMode() {
        visionPortal = VisionPortal.easyCreateWithDefaults(
                    hardwareMap.get(WebcamName.class, "Webcam 1"), aprilTag);

        telemetry.addData(">", "Touch Play to start OpMode");
        telemetry.update();

        // Wait for the DS start button to be touched.``
        waitForStart();

        if (opModeIsActive()) {
            // ...
        }

        // Save more CPU resources when camera is no longer needed.
        visionPortal.close();
    }
}

---

@Autonomous(name = "Example VisionPortal OpMode")
public class ExampleVisionPortalOpMode extends LinearOpMode {

Declares our LinearOpMode and annotates it as an autonomous program. LinearOpMode is often more useful when coding autonomous routines due to its inherent structure.

---

    /**
     * The variable to store our instance of the AprilTag processor.
     */
    private AprilTagProcessor aprilTag;

    /**
     * The variable to store our instance of the vision portal.
     */
    private VisionPortal visionPortal;

Some convenience variables that will let us store our VisionProcessor and VisionPortal instances that we will be using later on.

---

    @Override
    public void runOpMode() {

Inherits the method from LinearOpMode that will be executed when the OpMode is initialized. Any code put in here will be executed as a result.

---

        // Create the AprilTag processor the easy way.
        aprilTag = AprilTagProcessor.easyCreateWithDefaults();
        
        // Create the vision portal the easy way.
        visionPortal = VisionPortal.easyCreateWithDefaults(
                hardwareMap.get(WebcamName.class, "Webcam 1"), aprilTag);

This is the key part of our image processing initialization; we'll create our AprilTagProcessor and VisionPortal instances by using easyCreateWithDefaults()methods, which allows us to effortlessly initialize things by only passing a few parameters.

We'll make a special emphasis on this part;

hardwareMap.get(WebcamName.class, "Webcam 1")

This line basically defines what will be the source of our images that are passed onto the attached VisionProcessors, usually a webcam for that matter. "Webcam 1" indicates the robot configuration name of the image capture device we wish to use, as it is commonly the default name automatically assigned by the FTC SDK.

In the case of EOCV-Sim, fortunately we have quite some other options here in order to provide more flexibility when it comes to testing your vision code;

Using other input sources in your OpModes

Type	WebcamName
USB Camera	"Webcam 1" refers to the first USB camera detected by your operating system In order to use other cameras, you will need to enter their index number. "0" is the same as "Webcam 1", but you can specify any number that ranges from 0 to (n-1), where n is the number of USB cameras currently plugged.
Image	Images are specified by providing their absolute path as a WebcamName, the simulator automatically determines if it's an image by the file's extension. Examples: "C:\Users\pepito\Pictures\OnePixel.png" "/Users/PepitoRico/Downloads/OnePixel.png"
Video	Videos are pretty much the same as images, as they are specified by providing their absolute path as a WebcamName, the simulator automatically determines if it's an video by the file's extension. Note that mp4 is most likely not supported due to licensing issues. Examples: "C:\Users\pepito\Pictures\10PixelsVideo.avi" "/Users/PepitoRico/Downloads/10PixelsVideo.mkv"

WebcamName code examples

USB Cameras

hardwareMap.get(WebcamName.class, "Webcam 1");

hardwareMap.get(WebcamName.class, "0"); // Same as "Webcam 1"
hardwareMap.get(WebcamName.class, "1"); // Other webcam
hardwareMap.get(WebcamName.class, "2"); // Other webcam

Images

hardwareMap.get(WebcamName.class, "C:\Users\pepito\Pictures\OnePixel.png");

Videos

hardwareMap.get(WebcamName.class, "/Users/PepitoRico/Downloads/10PixelsVideo.avi");