# Revision history [back]

Hi Dong_ym, I think that the reason why you cannot see in the /scan_multi the obstacles of the back is because you are using the default configuration of the ira_laser_tool. By default, the ira_laser_toolpackage does not produce the /scan_multi from -PI to +PI, but some other weird values.

The solution, is to use the rqt_reconfigure tool to set the angle_min and angle_max parameters to -PI and +PI respectively. To do that, open the tool with the command:

rosrun rqt_reconfigure rqt_reconfigure


You should see something like in the picture attached. Then, just change the angle values. I recommend you change that while watching the scan in rviz so you will see clearly how the scan changes based on your values.

I have created, too, a video showing how I did that for a Turtlebot with two lasers. Find the video here.

Hope it helps.

Hi Dong_ym, I think that the reason why you cannot see in the /scan_multi the obstacles of the back is because you are using the default configuration of the ira_laser_tool. By default, the ira_laser_toolpackage does not produce the /scan_multi from -PI to +PI, but some other weird values.

The solution, is to use the rqt_reconfigure tool to set the angle_min and angle_max parameters to -PI and +PI respectively. To do that, open the tool with the command:

rosrun rqt_reconfigure rqt_reconfigure


You should see something like in the picture attached. Then, just change the angle values. I recommend you change that while watching the scan in rviz so you will see clearly how the scan changes based on your values.

I have created, too, a video showing how I did that for a Turtlebot with two lasers. Find the video here.

Hope it helps.

Hi Dong_ym, I think that the reason why you cannot see in the /scan_multi the obstacles of the back is because you are using the default configuration of the ira_laser_tool. By default, the ira_laser_toolpackage does not produce the /scan_multi from -PI to +PI, but some other weird values.

The solution, is to use the rqt_reconfigure tool to set the angle_min and angle_max parameters to -PI and +PI respectively. To do that, open the tool with the command:

rosrun rqt_reconfigure rqt_reconfigure


You should see something like in the picture attached. Then, just change the angle values. I recommend you change that while watching the scan in rviz so you will see clearly how the scan changes based on your values.

I have created, too, a video showing how I did that for a Turtlebot with two lasers. Find the video here.

Hope it helps.