Unit5 & Unit6 first launch commands throwing errors and rviz not showing any map

In unit5 the first launch command is throwing errors and the potential field is not being rendered in rviz. Same problem in Unit6 , no map is rendered in rviz.

Hi @nayakluckykant01 ,

could you be more specific and tell us which command have you tried on Unit5 and on Unit6?

Could you paste here the errors you are getting?

If the command you have executed is the one below:

roslaunch unit5 unit5_exercise.launch

I suppose you have the unit5 package, and the unit5_exercise.launch created, right? If you definitely have this package and this launch file in your ~/catkin_ws/src, please make sure you source your workspace before trying it just to make sure:

source ~/catkin_ws/devel/setup.bash

Also, if the error messages are not clear when calling roslaunch, you can use the –screen parameter so that the logs go to the screen. Example:

source ~/catkin_ws/devel/setup.bash

roslaunch unit5 unit5_exercise.launch --screen

Please keep us informed.


after trying the last launch command , I’m getting the errors below :

And I’m not able to get the expected result in rviz by using 2D Nav Goal after the ready to accept command appears . the potential field is not getting rendered in rviz. Same thing happening in unit6 also.

Hi @nayakluckykant01,

according to the logs, the error is when trying to execute a file named costmap_to_gridmap that is expected to be in the unit5 package.

If it is complaining about this file, the reasons for this are possibly the following:

  • You have not created this executable by compiling your workspace with cd ~/catkin_ws; catkin_make
  • You have not modified the CMakeLists.txt file in order to compile that file.

Have you followed any instructions to create that costmap_to_gridmap file?

In order to see if the file really exists, you can run the following command:

find ~/catkin_ws -name costmap_to_gridmap

If that doesn’t show any file, then the file definitely does not exist and you have to create it following the instructions of the notebook.


Hello @nayakluckykant01 ,

as @ralves pointed out, you need to build the catkin workspace before running the exercise.

The course has been updated to remind about this step.

I hope you are enjoying the course so far, many thanks for your feedback!