title: openCV Gaussian blur/smoothing of 3D Matrix/Histogram
body: <p>I have a (3D) Histogram which I like to apply Gaussian smoothing on:</p>
  
  <pre><code>cv::MatND Hist;
  </code></pre>
  
  <p>In the 1D and 2D cases I blur it via:</p>
  
  <pre><code>cv::GaussianBlur(Hist, Hist, cv::Size(1,3), 1.0);// 1D case
  cv::GaussianBlur(Hist, Hist, cv::Size(3,3), 1.0);// 2D case
  </code></pre>
  
  <p>But I struggle to apply Gaussian blurring in the 3D case.</p>
  
  <p>Has anyone got an idea how to attempt this?</p>