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Diamondback Users Please Note

With the release of Diamondback, the Python Camshift function in OpenCV somehow got broken and will crash with the following error:

TypeError: <unknown> is not a numpy array

right after selecting a region with the mouse to track. The only fix at the moment seems to be to overlay the C-Turtle version of the vision_opencv stack and then set your ROS_PACKAGE_PATH and PYTHONPATH environment variables to pick up this version before Diamondback's version. To do this on your machine, follow these steps:

$ sudo apt-get install ros-cturtle-vision-opencv
$ cd
$ echo -e "\nexport ROS_PACKAGE_PATH=/opt/ros/cturtle/stacks/vision_opencv:$ROS_PACKAGE_PATH" >> .bashrc
$ echo -e "\nexport PYTHONPATH=/opt/ros/cturtle/stacks/vision_opencv/opencv2/lib:$PYTHONPATH" >> .bashrc
$ source .bashrc

(The last command is only necessary in any currently open terminal windows. The path changes will be automatically picked up in any new terminal windows you launch in the future.)


Please see external documentation at

Wiki: pi_head_tracking_tutorial (last edited 2011-06-17 16:09:02 by Patrick Goebel)