The <remap> tag allows you to pass in name remapping arguments to the ROS node that you are launching in a more structured manner than setting the args attribute of a <node> directly. The <remap> tag applies to all subsequent declarations in its scope (<launch>, <node> or <group>).
- Name that you are remapping.
- Target name.
For example, you are given a node that says it subscribes to the "chatter" topic, but you only have a node that publishes the "hello" topic. They are the same type, and you want to pipe your "hello" topic into the new node which wants "chatter" by simply:
<remap from="chatter" to="hello"/>