title: Explanation of rho and theta parameters in HoughLines
body: <p>Can you give me a quick definition of <code>rho</code> and <code>theta</code> parameters in <a href="http://docs.opencv.org/3.1.0/dd/d1a/group__imgproc__feature.html#ga46b4e588934f6c8dfd509cc6e0e4545a" rel="noreferrer">OpenCV's HoughLines</a> function</p>
  <pre><code>void cv::HoughLines (   InputArray  image,
      OutputArray     lines,
      double  rho,
      double  theta,
      int     threshold,
      double  srn = 0,
      double  stn = 0,
      double  min_theta = 0,
      double  max_theta = CV_PI 
  )
  </code></pre>
  <p>The only thing I found in the doc is:</p>
  <blockquote>
  <p>rho: Distance resolution of the accumulator in pixels.</p>
  <p>theta: Angle resolution of the accumulator in radians.</p>
  </blockquote>
  <p>Do this mean that if I set <code>rho=2</code> then 1/2 of my image's pixels will be ignored ... a kind of stride=2 ?</p>