Advanced ROS Tutorials

Publish Update Part of Map

Often only a small portion of the map will be updated at a time. To increase performance and reduce the amount of data that has to be published between nodes, it is possible to define which part of the map should be published.

Publish Full Map to New Subscribers

If you followed the previous tutorial and now only publish the updated part of the map, you will notice that when nodes subscribe to the map at different times they will not receive the full map. In order to solve this, we have to detect when a new node is subscribing to our map and send the whole map to that node.

Another approach to solving this problem can be to publish the whole map every X seconds; however, when mapping at 5 mm the map will get huge, so this will eventually get slow.

Publish Multiple Depths

Mapping at a fine voxel size (2 cm or below) results in a lot of data. In a complete robotics system, different nodes require different map resolutions. It can therefore be beneficial to publish the map at different depths, and only publish at a specific depth if a node subscribes to the topic for that depth.