title: OpenCV aruco, Z-axis doesn't draw properly
body: <p>I have a problem with function drawAxis in aruco module. Z axis flip and general aren't at 90 degrees (X and Y works fine).</p>
  
  <p>The problem is illustrated by the screen:
  <a href="https://i.stack.imgur.com/8X58H.jpg" rel="nofollow noreferrer">flip axis</a></p>
  
  <p>I tried changed camera, detect another markers and do many recalibration (i tried different configuration of photos, between 15 and 100)</p>
  
  <p>When I printed vector of rotation (rvec) I noticed that angle 0 and 1 (x, y?) had small fluctuation, but angle 2 (z?) are in general constant:
  <a href="https://i.stack.imgur.com/4wvTP.jpg" rel="nofollow noreferrer">rvec print</a></p>
  
  <p>Where could be a problem? If X and Y axis work fine, code should be correct? It's normal that rvec_2 is constant? Or maybe t's my fault with calibration?</p>
  
  <p>Please for any clues!
  Regards!</p>