title: OpenCV linking problems with ROS
body: <p>I'm trying to compile <a href="https://github.com/tum-vision/lsd_slam" rel="nofollow">this</a> project (following the instructions given). When building it with <code>rosmake</code>, I get a bunch of <code>undefined reference to cv::String::deallocate()</code> and <code>undefined reference to cv::String::allocate(unsigned long)</code>. I find curious that I'm getting an error just in those functions while the rest of the OpenCV functions seem to be working properly. </p>
  
  <p>I know this happens because the linker can't find the objects where these functions were compiled to, but I'm kind of new to the ROS build system and can't find what's wrong.</p>
  
  <p>I've tried using the <code>CMakeLists.txt</code> file provided, and also adding <code>find_package(OpenCV REQUIRED)</code> and <code>target_link_libraries(xxx xxx ${OpenCV_LIBRARIES})</code>, without that making any difference. I know OpenCV is installed and compiled properly (I've used it before), and I had installed ROS without any problems. </p>
  
  <p>I'm using OpenCV 3, ROS Indigo, Ubuntu 14.04</p>