OpenCv2: Using HoughLinesP raises " is not a numpy array"
For me, it wasn't working when the environment was of ROS Fuerte but it worked when the environment was of ROS Groovy. 
As Alexandre had mentioned above, it must be the problem with the opencv2 versions. Fuerte had 2.4.2 while Groovy had 2.4.6
Using HoughLinesP raises  "<'unknown'> is not a numpy array", but my array is really a numpy array.
It works on one of my computer, but not on my robot...