title: qt_visualizer tutorial pointcloud doesnt appear
body: <p>I compiled PCL1.10.1 against VTK 8.2.0 and try to start using PCL in my QT Gui Project like pcl
  s qt_visualizer tutorial.
  <a href="https://pcl.readthedocs.io/projects/tutorials/en/latest/qt_visualizer.html#qt-visualizer" rel="nofollow noreferrer">https://pcl.readthedocs.io/projects/tutorials/en/latest/qt_visualizer.html#qt-visualizer</a></p>
  <p>The pointcloud doesnt appear. The renderwindow works. I could change backgrundcolor and add a coordinateaxis.
  <a href="https://i.stack.imgur.com/z4Eia.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/z4Eia.png" alt="enter image description here" /></a>
  I copied the code from doc/tutorials/content/sources/qt_visualizer</p>
  <p>I used cmake 3.16.3. According to</p>
  <pre><code>dpkg -s libboost-dev | grep 'Version'
  </code></pre>
  <p>boost version is 1.71.0.0ubuntu2</p>
  <p>Any ideas?</p>