LaserScanLayer overlapping when I subscriber the topic “/scan”

edit

First step:

In PC (Ubuntu 14.04) , I ssh to the kobuki and bring up it with this command line

roslaunch turtlebot_bringup  minimal.launch --screen &

and then start the gmapping with this command line

roslaunch turtlebot_navigation gmapping.launch

then the Turtlebot is normal start.

Second step:

In PC ,start the new session in terminal，echo the "/scan" topic, scan data is well,but the problem like this.Left side of laser scan visualization on android gets weird

This is the LaserScanLayer code: LaserScanLayer

Could you help me?

Thanks!