title: Opencv Repeatability Result not make sense?
body: <p>i'm trying to evaluate SIFT and SURF Detectors by Repeatability criteria.</p>
  
  <p>i find out that below method can find Repeatability ,Correspondence  of SIFT and SURF</p>
  
  <pre><code> cv::evaluateFeatureDetector(img_1c, img_2c, h12, &amp;key_points_1, &amp;key_points_2, repeatability, corrCounter);
  </code></pre>
  
  <p>some of the result are listed below:</p>
  
  <pre><code>Number  Repeatibility   Correspond  Keypoint 1st    Keypoint 2th    
  1to2    0.7777778            140        224              180    
  1to3    0.7125               114        224              161    
  1to4    0.704918              86        224              123    
  1to5    0.6853933             61        224               89    
  1to6    0.6521739             45        224               69
  </code></pre>
  
  <p>for first row repeatibility can compute as --> (correnspond)/min(keypoint1st,keypoint2th) = (140/180) =  0.7777778
  but for other rows it's value is different from what i compute with above formula.</p>
  
  <p>can somebody tell why is that happening?</p>
  
  <p>Regards.</p>