modified README

README.md

@@ -1,8 +1,25 @@
+Installation:
+
 ```
 cd /opt/ros/indigo/stacks/
 git clone https://github.com/laboshinl/loam_velodyne.git
 cd loam_velodyne
 cmake .
 rosmake
+```
+
+Running:
+```
 roslaunch loam_velodyne.launch
 ```
+
+In second terminal play sample velodyne data from rosbag (http://www.frc.ri.cmu.edu/~jizhang03/Datasets/nsh_indoor_outdoor.bag):
+```
+rosbag play ~/Downloads/nsh_indoor_outdoor.bag 
+```
+
+Or read from velodyne pcap (http://midas3.kitware.com/midas/download/item/215411):
+```
+roslaunch velodyne_pointcloud 32e_points.launch calibration:=/home/laboshinl/calib.yaml pcap:="/home/laboshinl/Downloads/velodyne.pcap"
+```
+