Camera

The quadcopter’s cameras allow you to capture high-quality images and integrate them directly into your custom computer vision programs.

Initialization

To control the quadcopter, instantiate a Clover2 object.

from clover2 import Clover2

drone = Clover2()
# or with a specific node name:
drone = Clover2("my_drone")

Clover2 serves as a wrapper around a ROS 2 node. Upon instantiation, the node is initialized, and a background thread is launched to handle ROS 2 operations.

How to Retrieve a Frame as a NumPy Array

Use get_image() to retrieve the current camera frame as a NumPy array.

img = drone.camera.get_image()                      # Default: retrieves from 'main_camera' in 'bgr8' format
img = drone.camera.get_image("main_camera", "rgb8") # Custom: specifying the camera name and encoding

If no parameters are provided, get_image() defaults to main_camera and bgr8 format. You can customize the source and format using the camera_name and encoding parameters.

How to Retrieve a ROS Image

If you need to pass images directly through ROS topics, use get_image_msg().

img_msg = drone.camera.get_image_msg()

This method is more efficient if your program runs on ROS 2 and you do not need to immediately convert the image into a NumPy array.

How to Retrieve Camera Calibration Parameters

To get the camera calibration data, use get_camera_info().

info = drone.camera.get_camera_info()
# info.width, info.height, info.k (matrix), info.d (distortion)

Example: QR Code Detection

This example demonstrates how to detect and decode a QR code in real-time.

import cv2
from clover2 import Clover2

drone = Clover2()
detector = cv2.QRCodeDetector()

while True:
    img = drone.camera.get_image()
    data, bbox, _ = detector.detectAndDecode(img)
    if data:
        print(f"QR Code: {data}")
        break

cv2.QRCodeDetector() initializes a specialized detector object from the OpenCV library. The while True loop continuously retrieves the latest frame from the camera using img = drone.camera.get_image(). The detectAndDecode() function scans the frame for a QR code and attempts to extract the encoded text data. Once a valid QR code is identified and its data is printed to the console, the break stops the capture process.