[ros-users] Why the SLAM have more than one maps in RVIZ?

Hello, everybody!
When I'm using gmapping to be SLAM in rviz, with the robot running there
will generate more than one maps in RVIZ?

Thank you for your attention.
Best regards.

--
Gong Shujun
Shenzhen Institute of Advanced Integration Technology
Chinese Academy of Sciences
The Chinese University of Hong Kong
No. 1068 Xueyuan Avenue, Shenzhen University Town,
Nanshan District, Shenzhen, China