Road Network Description File Annotation

1. Course Content

• Use the route_tool tool to annotate the .geojson format file describing the road network

Course Objectives

• Master the methods of road network file annotation, editing, and modification

2. Road Network Annotation

ros2 launch microros_v2_bringup toolbox_location_nav.launch.py rviz_config:=roadnet_edit

• Rviz will display the map and two coordinate frames: map is the map coordinate frame, and base_footprint is the coordinate frame of the projection point of the robot chassis center on the ground. Through base_footprint, we can know the robot's exact position on the map in real time

2.1 Adding Waypoints

• Click the Publish Point tool in the Rviz toolbar to enter waypoint selection mode

• Then click the left mouse button on the small blue dot at the center of the base_footprint coordinate frame. The position field in the Route Tool tab at the bottom left will automatically be filled with the coordinates of the current point, and then click Create to create a waypoint

• Next, move the robot to the next position where a waypoint needs to be marked. In this demonstration, the robot is directly moved to the next position to be marked

[!TIP]

The robot can be moved via keyboard control, gamepad control, 2D Goal Pose navigation in rviz, or even by physically carrying the robot to the next position to be marked, because the pose map allows the robot's global position to be quickly and accurately located

• As you can see, because the robot was physically moved, the global localization was lost, and the laser contour no longer matches the map environment features. Here we can use the pose map to quickly relocalize

• Click the 2D Pose Estimate tool in the Rviz toolbar

• Then give an estimated pose near the approximate position of the robot

• Afterwards, the robot's accurate position on the global map will be restored immediately

[!TIP]

• The principle of quick relocalization here is to use slam_toolbox pure localization and the pose map for fast scan-map matching
• Note: If, during subsequent waypoint annotation, you observe a deviation between the laser contour and the map environment features (due to odometry cumulative error, wheel slippage, manual displacement, or other factors causing local localization errors), you can use this method to quickly restore the robot's accurate position.

• Repeat the above steps until all waypoints that need to be marked are done (annotate waypoints according to the user's actual needs)
• After finishing the annotation, you can first turn off the TF and LaserScan on the left to check the waypoints

3.3 Adding Edges

• Select Edge in the Route Tool tab

• Fill in the starting waypoint of the edge in Start Node ID and the ending waypoint of the edge in End Node ID, then click Create to create an edge between waypoints

[!IMPORTANT]

Note!!!

A road network is a topological structure composed of points and edges, and edges are directional. For example, the edge 0---->1 created here is one-way. If a bidirectional edge is needed, you must also create the edge 1---->0.

• Then we also create the 1-0 edge so that waypoints 0 and 1 can be traveled in both directions

• Repeat the above steps to create all edges (whether the edges created here are one-way or bidirectional depends on the actual scenario requirements)

4. Saving the Road Network Description File

• Click save in the Route Tool tab, then in the pop-up window select the path where the file will be saved. Here we select the ~/map path, fill in the file name in the File name field (it is recommended to keep it consistent with the grid map name for easy distinction), and the file suffix must be .geojson. Finally, click save to save the road network description file

• After saving successfully, the terminal will print a confirmation message

• Afterwards, we can directly view the map.geojson road network description file from the ~/map path on the host machine. The file contains a JSON-format description of the waypoint and edge information

5. Loading and Modifying the Road Network Description

5.1 Loading the Road Network Description File

• If you need to modify a previously created road network description file later, for example adding, removing, or editing points and edges, you can load the previous road network description file for editing

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ros2 launch microros_v2_bringup toolbox_location_nav.launch.py rviz_config:=roadnet_edit

5.2 Editing the Road Network

• If you need to add new waypoints and edges, the operations are the same as the previous steps
• Click Edit to re-edit the information of an existing waypoint or edge

• Click Remove to remove an existing waypoint or edge