A collection of tools for making complex "selections" in RVIZ with a lasso tool ala photoshop or blender. This works by recording the polygon that the user drew along with the pose of the users camera. This info is published over ROS and external nodes can use it.
Try the demo:
rosrun rviz_lasso_tool rviz_lasso_tool_demo _pcd_path:=PATH_TO_YOUR_PCD_FILE
And in another thread, run Rviz, load the rviz lasso tool and go to town. Press control to add to the current selection and shift to remove from it.