ROS RVIZ: How to visualize a point cloud that doesn't have a fixed frame transform

rviz is missing the transformation from its given Fixed Frame (i.e. map) to the frame of your point cloud data (i.e. base_link). If you are working with ROS by means of measurement data, kinematics and dynamics, I highly recommend the tf-tutorials on that.

However, there are two options two fix your issue:

1. You can create a publisher which tells rviz how to transform the base_link frame into the map frame by typing the following command into your command line:

rosrun tf static_transform_publisher 0 0 0 0 0 0 map base_link 50

This command, explanation here, publishes the information that both frames coinside, with 50 Hz.

2. Another option is to tell rviz that its fixed frame should be base_link. So just alter map to base_link as proposed in the image below.