title: Cmake GUI could not find boost (missing: system python3) (found version "1.72.0"), on Windows 10
body: <p>I am trying to install <a href="https://github.com/FORTH-ModelBasedTracker/PyOpenPose" rel="nofollow noreferrer">PyOpenPose</a> on Windows 10, using Cmake GUI. It requires OpenCV so I downloaded the prebuild OpenCV for Windows. Then I cmake the repository, import the OpenCV directory, everything is ok, until it required Boost. I downloaded the latest Boost version 1.72.0 and copy it to <code>C:\boost\boost_1_72_0</code>, since the installation manual tells me to do that to get CMake to detect the Boost. But its detection was like this:</p>
  
  <p><a href="https://i.stack.imgur.com/oEvfB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oEvfB.png" alt="enter image description here"></a></p>
  
  <p>By reading it I guessed Cmake has detected the Boost but it could not detect the python, the missing is <code>system python3</code> and the Boost 1.72.0 has been found. So I add a <code>DPYTHON_EXECUTABLE</code> and set its path to <code>C:\Users\abc\AppData\Local\Programs\Python\Python38\python.exe</code> but the problem still remains.</p>
  
  <p>Those <code>DBOOST_LIBRARYDIR</code> and <code>DBOOST_ROOT</code> were added by me. Cmake exports the same errors even without those arguments.</p>
  
  <p>So that I am stuck here.</p>