updated readme

README.md

@@ -243,17 +243,23 @@ Useful for debug output are:
 
 ## 3.2 LSD-SLAM Viewer
 The viewer is only for visualization. It can also be used to output a generated point cloud as .ply.
-Start it using
+For live operation, start it using
 
     rosrun lsd_slam_viewer viewer
 
 You can use rosbag to record and re-play the output generated by certain trajectories. Record & playback using
 
-    rosbag record /lsd_slam/graph /lsd_slam/keyframes /lsd_slam/liveframes -o file.bag
-    rosbag play file.bag
+    rosbag record /lsd_slam/graph /lsd_slam/keyframes /lsd_slam/liveframes -o file_pc.bag
+    rosbag play file_pc.bag
 
 You should never have to restart the viewer node, it resets the graph automatically.
 
+If you just want to lead a certain pointcloud from a .bag file into the viewer, you 
+can directly do that using 
+
+    rosrun lsd_slam_viewer viewer file_pc.bag
+
+
 
 ### 3.2.1 Useful Hotkeys