I am following this tutorial (http://gazebosim.org/tutorials/?tut=ros_depth_camera) to include the Kinect camera with plugin model (sdf file) in the Gazebo world directly. However, in Rviz fixed frame in the left panel, I cannot find the "camera_link".

The rostopic related to camera can be published successfully:

/camera/color/camera_info
/camera/color/image_raw
/camera/color/image_raw/compressed
/camera/color/image_raw/compressed/parameter_descriptions
/camera/color/image_raw/compressed/parameter_updates
/camera/color/image_raw/compressedDepth
/camera/color/image_raw/compressedDepth/parameter_descriptions
/camera/color/image_raw/compressedDepth/parameter_updates
/camera/color/image_raw/theora
/camera/color/image_raw/theora/parameter_descriptions
/camera/color/image_raw/theora/parameter_updates
/camera/depth/camera_info
/camera/depth/image_raw
/camera/depth/points
/camera_ir/parameter_descriptions
/camera_ir/parameter_updates

However, I cannot see the kinect camera image in Rviz because of the missing camera_link frame.

I am using Gazebo 9.0.0 with Ros Melodic (Ubuntu 18.04). Can anyone help me with the error?