title: Why is OpenCV_FOUND set to false?
body: <p>To start off, I know this question has too many duplicates, but none of them work in my case.</p>
  
  <p>I have installed OpenCV 2.4.13.2 on my Ubuntu 16.04 system.  I followed the installation instructions outlined here: <a href="http://www.pyimagesearch.com/2016/10/24/ubuntu-16-04-how-to-install-opencv/" rel="nofollow noreferrer">http://www.pyimagesearch.com/2016/10/24/ubuntu-16-04-how-to-install-opencv/</a>.  As per step#6 mentioned therein, I could confirm that OpenCV was installed successfully.</p>
  
  <p>However, when I try to run <code>cmake ..</code> while building this project: <a href="https://github.com/andrewssobral/vehicle_detection_haarcascades/" rel="nofollow noreferrer">https://github.com/andrewssobral/vehicle_detection_haarcascades/</a>, I get an error saying:</p>
  
  <blockquote>
    <p>Found OpenCV Windows Pack but it has not binaries compatible with your
      configuration.</p>
    
    <p>You should manually point CMake variable OpenCV_DIR to your build of OpenCV
      library.
    Call Stack (most recent call first):
      CMakeLists.txt:5 (find_package)</p>
    
    <p>CMake Error at CMakeLists.txt:5 (find_package):
      Found package configuration file:</p>
    
    <p>/home/abhishek/opencv-2.4.13.2/cmake/OpenCVConfig.cmake</p>
    
    <p>but it set OpenCV_FOUND to FALSE so package "OpenCV" is considered to be
      NOT FOUND.</p>
    
    <p>-- Configuring incomplete, errors occurred!
    See also "/home/abhishek/opencv-2.4.13.2/vehicle_detection_haarcascades/build/CMakeFiles/CMakeOutput.log".</p>
  </blockquote>
  
  <p>As mentioned in other SO answers, I tried deleting the cache files, reinstalling, reinstalling in a different directory, etc., but none of them works.  So, how can I overcome this error?  I am going to use this vehicle detection project (developed majorly in C++) in an academic setting and I would greatly appreciate your help!</p>