I am running ROS Indigo on Ubuntu 14.04. I am doing a mono-camera calibration and trying to follow the camera calibration tutorial on the ROS Wiki.

I give the following command:

rosrun camera_calibration cameracalibrator.py --size 8x6 --square 0.108 image:=/my_camera/image camera:=/my_camera

I get the following error:

ImportError: numpy.core.multiarray failed to import Traceback (most recent call last): File "/opt/ros/indigo/lib/camera_calibration/cameracalibrator.py", line 47, in import cv2 ImportError: numpy.core.multiarray failed to import

I thought it was to do with updating numpy and did a rosdep update but no difference.

What is a possible way to solve this problem?

UPDATE: I uninstalled and reinstalled ROS completely from scratch. I still get the same error. Should I have to look somewhere outside ROS?


Install OpenCV-Python, it will solve the import cv2 error.

You can refer the following link for installation, Install OpenCV-Python in Windows.


Are you doing stereo or mono camera calibration? Can you post more code? (Please update the question, don't post code in a comment on this answer)

I ask because there's a few things to check. Highlights from the tutorial:

Start by getting the dependencies and compiling the driver.

$ rosdep install camera_calibration

$ rosmake camera_calibration

Make sure that your monocular camera is publishing images over ROS. List the topics to check that the images are published:

$ rostopic list

This will show you all the topics published, check to see that there is an image_raw topic. The default topics provided by most ROS camera drivers are: /camera/camera_info /camera/image_raw If you have multiple cameras or are running the driver in its own namespace, your topic names may differ.

  • $\begingroup$ Hi. So I am doing a mono-camera calibration. There is no more code to post since I am using the default ROS node. You are right about the topic names since uvc_camera pulishes in the topic /image_raw but that will not solve the error and does not as I checked it. Regarding repos, they are up to date. $\endgroup$ – Nagsaver Oct 7 '15 at 1:31
  • $\begingroup$ @Nagsaver - What is the namespace of the camera you are using? Does it match the definition you are using? (camera:=\my_camera) What do you get when you list topics? Do you get any errors when you install/make camera_calibration? $\endgroup$ – Chuck Oct 7 '15 at 1:41
  • $\begingroup$ I get /image_raw and /camera_info as the topics when I do rostopic list. I tried with the new topic names and it gives the same error as expected because the error is related to numpy. Regarding the camera_calibration package,it builds successfully without any errors when I do rosmake. $\endgroup$ – Nagsaver Oct 7 '15 at 1:50

Did you try updating numpy directly? rosdep does not care about pip packages.

sudo pip install numpy -U

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