title: xfeatures2d not found in OpenCV on Ubuntu
body: <p>I am using OpenCV version 3.2.0 and xfeatures2d is not found on this. Is there any way I can install this to the same version of OpenCV?</p>
  
  <pre><code>&gt;&gt;&gt; import cv2
  &gt;&gt;&gt; help(cv2.xfeatures2d)
  Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
  AttributeError: 'module' object has no attribute 'xfeatures2d'
  </code></pre>