Calculus FOV ( Field of View ) of ARCore camera

MainActivity.java

@Override
public void onUpdate(FrameTime frameTime) {
    Log.e(TAG, "Elephant rotation angle: " + rotationAngle);

    // from arcore
    try {
        Frame frame = arFragment.getArSceneView().getSession().update();
        Camera camera = frame.getCamera();
        CameraIntrinsics intrinsics = camera.getImageIntrinsics();

        float focalLenght = intrinsics.getFocalLength()[0];
        int[] size = intrinsics.getImageDimensions();
        int w = size[0];
        int h = size[1];

        double fovW = Math.toDegrees(2 * Math.atan(w / (focalLenght * 2.0f)));
        double fovH = Math.toDegrees(2 * Math.atan(h / (focalLenght * 2.0f)));

        Log.e(TAG, String.format("ARCore - fovW: %f, fovH: %f", fovW, fovH));

    } catch (CameraNotAvailableException e) {
        e.printStackTrace();
    }


    // from camera2 api
    try {
        String cameraId = arFragment.getArSceneView().getSession().getCameraConfig().getCameraId();

        CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
        CameraCharacteristics cameraCharacteristics = cameraManager.getCameraCharacteristics(cameraId);

        float[] maxFocus = cameraCharacteristics.get(CameraCharacteristics.LENS_INFO_AVAILABLE_FOCAL_LENGTHS);
        SizeF size = cameraCharacteristics.get(CameraCharacteristics.SENSOR_INFO_PHYSICAL_SIZE);
        float h = size.getHeight();
        float w = size.getWidth();

        double fovW = Math.toDegrees(2 * Math.atan(w / (maxFocus[0] * 2.0f)));
        double fovH = Math.toDegrees(2 * Math.atan(h / (maxFocus[0] * 2.0f)));

        Log.e(TAG, String.format("Camera2 - fovW: %f, fovH: %f", fovW, fovH));

    } catch (CameraAccessException e) {
        e.printStackTrace();
    }
}

Reference

• How to calculate field of view in arcore?
• Acquire FOV from ARCore