title: How to merge bounding boxes with groupRectangle?
body: <p>I have an image with bounding boxes like so:</p>
  
  <p><a href="https://i.stack.imgur.com/zENnC.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/zENnC.jpg" alt="enter image description here"></a></p>
  
  <p>I want to merge overlapping bounding boxes. </p>
  
  <p>I tried: <code>cv::groupRectangles(detected, 1, 0.8)</code></p>
  
  <p>My expectation was that I get a single box for each cluster. </p>
  
  <p>But I got this:</p>
  
  <p><a href="https://i.stack.imgur.com/k8J6Q.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/k8J6Q.jpg" alt="enter image description here"></a> </p>
  
  <p>As you can see, <strong>the problem is, there is no box for the dartboard in the middle and for the right one</strong>.</p>
  
  <p>How do I resolve this? I would preferably like to use the OpenCV api rather than coding my own merging algorithm. </p>
  
  <p>I see that it eliminates regions bounded by exactly one box. I want it to not  do that. </p>
  
  <p>I have tried tweaking the parameters randomly but I've gotten much worse results. I would love some guidance in the right direction. </p>