title: GDB to debug OpenCV in ROS
body: <p>I used OpenCV in my ROS codebase. I saw a segmentation fault in a function in OpenCV. It may not be a problem in OpenCV, but it'll be helpful for me to debug if I know what exactly the error is.</p>
  
  <p>However, the symbol table is not available:</p>
  
  <pre><code>(gdb) bt full
  #0  0x00007ffff633eefe in CvANN_MLP::predict(cv::Mat const&amp;, cv::Mat&amp;) const () from /opt/ros/hydro/lib/libopencv_ml.so.2.4
  No symbol table info available.
  </code></pre>
  
  <p>I have linked OpenCV in the CMakeList.txt.</p>
  
  <pre><code>find_package(OpenCV REQUIRED)
  target_link_libraries(agentlib debug ${OpenCV_LIBS})
  </code></pre>