How to understand the result of the "ros2 topic info /camera/color/image_raw" is 0
When I launch realsense_ros2_camera
,I use ros2 topic info /camera/color/image_raw
to print information about the /camera/color/image_raw topic,the result is :
Topic: /camera/color/image_raw
Publisher count: 0
Subscriber count: 0
In subscriber,it can't auto call the callback function.I want to know if it is because there is no publisher lead to can't auto call the callback function.
To be honest,I don't understand that there is no publisher why does the topic exist.
Thanks very much.