Package overview

The translate_coords package contains nodes for converting pixel coordinates from an overhead depth camera to movebase goals intended for a mobile robot.

Nodes

cam_to_depthcoords.py

Deprojects pixel coordinates from an overhead depth camera into 3D points in the camera coordinate system, measured in meters.

The 3D points are XYZ coordinates with X being the horizontal distance to the camera side to side, Y being the horizontal distance up and down, and Z being the vertical distance. Note that this coordinate system follows the Left Hand Rule.

Info

Default node name: cam_to_depthcoords

Dependencies: rospy, ros_numpy, cv_bridge, geometry_msgs, sensor_msgs, numpy, pyrealsense2

ROS Rate: 30hz

Topics

Subscribes

  • /camera/depth/camera_info (sensor_msgs/CameraInfo): The intrinsic parameters from the overhead camera.

  • /camera/aligned_depth_to_color/image_raw (sensor_msgs/CameraInfo): The depth image frames from the overhead camera.

  • input_coords (geometry_msgs/Point): The 2D coordinates to deproject into 3D points.

Publishes
  • depth_coords (geometry_msgs/Point): The deprojected 3D points, measured in meters.

cam_transform.py

Broadcasts a static transform from the map frame to the camera base frame.

Info

Default node name: cam_tf_broadcaster

Dependencies: rospy, tf2, geometry_msgs

ROS Rate: none

Parameters

  • ~tf_pos ([float, float, float]): XYZ translation for transform. Defaults to [0, 0, 0].
  • ~tf_rot ([float, float, float, float]): Quaternion rotation for transform. Defaults to [0, 0, 0, 0].
  • ~map_frame (string): Name of map frame. Defaults to ‘map’.
  • ~cam_frame (string): Name of camera frame. Defaults to ‘_link’.

depth_to_mapcoords.py

Transforms 3D points in the camera coordinate system to the map frame.

It should be noted that ROS coordinates follow the Right Hand Rule whilst the camera coordinate system follows the Left Hand Rule, so the Z axis of the input points are flipped to account for this.

A transform between the camera frame and the map frame must be broadcast before this node starts, for example by starting the cam_transform node.

Info

Default node name: depth_to_mapcoords

Dependencies: rospy, tf2_ros, geometry_msgs, tf2_geometry_msgs

ROS Rate: 30hz

Topics

Subscribes
  • depth_coords (geometry_msgs/Point): The camera 3D points to translate.
Publishes
  • realworld_coords (geometry_msgs/PointStamped): The translated points, now in the map frame.

Parameters

  • ~map_frame (string): Name of map frame. Defaults to ‘map’.
  • ~cam_frame (string): Name of camera frame. Defaults to ‘_link’.
  • ~tf_timeout (float): Number of seconds to wait for a transform between the map and camera frame before timeing out.

goal_server.py

Sends 3D points in the map frame to the movebase Action server. Goals always have an orientation of [0, 0, 0] degrees.

Info

Default node name: goal_server

Dependencies: rospy, actionlib, move_base_msgs, geometry_msgs, tf

ROS Rate: none

Topics

Subscribes
  • goal_coords (geometry_msgs/PointStamped): The goals as 3D points in the map frame.

Parameters

  • ~map_frame (string): Name of map frame. Defaults to ‘map’.

Launch files

serve_goals

Starts and configures all nodes required to convert input camera pixel coordinates to movebase goals.

Does not start movebase or other navigation nodes.

Camera pixel coordinates can be input manually using the command rostopic pub -1 /input_coords geometry_msgs/Point "X" "Y" "0", where X and Y are replaced by integer values within the camera image width and height.

Info

Dependency Packages: realsense2_camera

Usage: roslaunch translate_coords serve_goals.launch

Arguments

  • serial_no (string): Serial number of overhead camera. Defaults to ‘’.
  • json_file_path (string): Defaults to ‘’.
  • camera (string): Camera name. Defaults to ‘camera’.
  • img_width (int): Width of depth and colour image from camera. Defaults to 848.
  • img_height (int): Height of depth and colour image from camera. Defaults to 480.

translate_tracker

Starts and configures all nodes required to track a 5x5 (size in squares) 50 (number of available IDs) ARUCO marker and translate the position into the map frame.

Does not start movebase or other navigation nodes.

Info

Dependency Packages: realsense2_camera, tango_tracker

Usage: roslaunch translate_coords translate_tracker.launch

Arguments

  • serial_no (string): Serial number of overhead camera. Defaults to ‘’.
  • json_file_path (string): Defaults to ‘’.
  • camera (string): Camera name. Defaults to ‘camera’.
  • img_width (int): Width of depth and colour image from camera. Defaults to 848.
  • img_height (int): Height of depth and colour image from camera. Defaults to 480.
  • marker_size (float): Width and height of the ARUCO marker which will be tracked in cm. Defaults to 7.3.