Camera Preprocessing

This package is responsible for calibrating the camera and preprocessing the images. Therefore it provides the following two nodes:

1. camera_calibration_node: Calibrates the camera
2. camera_preprocessing_node: Preprocess the raw image

Additionally, it provides the following classes to transform points and images:

1. CoordinateTransform: Transform points

from camera_preprocessing.transformation.coordinate_transform import CoordinateTransform

cordinate_transform = CoordinateTransform()

# Transform your points with the provided methods

2. Birdseye: Transform images into birdseye

from camera_preprocessing.transformation.calibration import Calibration
from camera_preprocessing.transformation.birds_eyed_view import Birdseye

calib = Calibration()
bev = Birdseye(calib)

# Transform the img to birdseye view (bev)
bev_img = bev.transform_img(img)

Please Note that this package is mandatory for using images in the smarty pipeline.

Camera Calibration

The camera calibration is done on the full image. The node uses the camera configuration (config/config.yaml), the calibration board images and the position board image to calibrate the distortion, intrinsics and extrinsic of the camera.

Usage

It exists a launchfile to calibrate the camera:

ros2 launch camera_preprocessing camera_calibration.launch.py

• params_file: Path to the ROS parameters file (default: config/ros_params.yaml).
• debug: Enable debug mode to show further images and configs (default: false).
• chessboard_path: Path to the chessboard image (default: none). With none the node will subscribe to the raw image topic and wait until it finds the chessboard.

Settings

The camera parameters are specified in config/config.yaml and contains the following parameters:

• recalibration_interval: Interval in seconds between recalibration (default: 7 days or 604800 seconds).

• focal_length: Focal length of the camera in millimeters. It is specified as a list with two values representing the focal length in the x and y directions.

• sensor_width_mm: Width of the camera sensor in millimeters.

• sensor_height_mm: Height of the camera sensor in millimeters.

• image_size: Width and height of the image in pixels. It is specified as a list with two values.

• target_size: Width and height of the target image in pixels. It is specified as a list with two values. This parameter can be used to resize the image to a different resolution.

• recalibrate: Boolean flag indicating whether the camera should be recalibrated.

• calibration_board:

  • board_size: Size of the calibration board in terms of the number of squares along the width and height. It is specified as a list with two values.
  • square_size: Size of each square on the calibration board in meters.

• method: Method used for external camera calibration (e.g., "chessboard").

  Note: This is the only currently implemented method

• position_board:

  • board_size: Size of the position board in terms of the number of squares along the width and height. It is specified as a list with two values.
  • square_size: Size of each square on the position board in meters.
  • world_points: List of 3D coordinates representing the world points on the position board. Each point is specified as a list with three values representing the x, y, and z coordinates in meters.

Additionally the following topics are specified in the config/ros_params.yaml file:

• calibration_file: Path to the calibration file where the calibration data will be saved (default: "config/calib.bin").
• config_file: Path to the configuration file containing camera parameters (default: "config/config.yaml").
• calibration_images_path: Path to the directory containing calibration images (default: "img/calib/Neue_3MP_Kamera/").
• image_topic: ROS topic from which raw camera images are received (default: "/camera/image_raw").

Camera Preprocessing

The camera preprocessing node subscribes to the raw image and publishes the undistorted and birdseye view image on the specified topics.

Usage

The preprocessing can be started by launching the following command:

ros2 launch camera_preprocessing camera_preprocessing.launch.py

The following parameters exist:

• params_file: Path to the ROS parameters file (default: config/ros_params.yaml).
• debug: Enable debug mode to show further images and configs (default: false).

Example for all parameters:

ros2 launch camera_preprocessing camera_preprocessing.launch.py params_file:=/path/to/ros_params.yaml debug:=true

Settings

The topics are defined as ros_parameters:

• calibration_file: Path to the calibration file where the calibration data will be saved (default: "config/calib.bin").
• config_file: Path to the configuration file containing camera parameters (default: "config/config.yaml").
• calibration_images_path: Path to the directory containing calibration images (default: "img/calib/Neue_3MP_Kamera/").
• position_calib_img_path: Path to the image used for position calibration (default: "img/position/chessboard.png").
• num_skip_frames: Number of frames to skip between processing (default: 1).
• image_topic: ROS topic from which raw camera images are received (default: "/camera/image_raw").
• undistorted_publisher_topic: ROS topic to which the undistorted images are published (default: "/camera/undistorted").
• birds_eye_publisher_topic: ROS topic to which the bird's eye view images are published (default: "/camera/birds_eye").