How to convert pruned global path into waypoints for external GCS

[peakyquest]

Hi, I’m using the Nav2 package for path planning, but my setup only uses the global planner (no local planner or controller). My goal is to get the global path after pruning and then convert that into waypoints that I can send to my custom Ground Control Station (GCS).
I have prune_path enabled so the global path stays updated and avoids obstacles dynamically. However, I’m not sure about the best way to extract the pruned global path and represent it as a set of waypoints that can be used externally.

Questions:
Is there a standard or recommended way to access the pruned global path as a list of waypoints? Does pruning modify the path in place, or should I subscribe to a specific topic to get the updated (pruned) version?
Any suggestions for converting this pruned path into a simplified list of waypoints suitable for a GCS interface?

Context:
Using global planner only prune_path = true

Want to export the updated path for a custom GCS that handles execution and visualization

Need to preserve obstacle avoidance behavior that comes from path pruning
Environment:

ROS 2 Humble (please adjust if needed)
Nav2 version: (e.g., 1.1.0)
Platform: Ubuntu 22.04
Any pointers, topics to subscribe to, or example nodes would be super helpful.
Thanks a lot for your work on Nav2! 🙏

[SteveMacenski]

What is "prune_path = true"? That is not a setting in which I am aware of in the planner server.

The planner server reports on the action response and on a topic that can be independently subscribed to the path from the start to the goal using your selected planning algorithm. This output is nav_msgs/Path which are simply a set of stamped poses that represent the path. You can pretty easily just convert those into waypoints or reduce the resolution if you want to have more sparse keypoints rather than a path that is relatively dense and continuous.