title: marker follow polyline when scroll on Google map api
body: <p>I came to this fantastic site and I would love to know how to create it.
  Here is the website:
  <a href="http://seidenstrasse.srf.ch/de/home.html" rel="nofollow">http://seidenstrasse.srf.ch/de/home.html</a></p>
  
  <p>Anyone know or can point me on how to move that circle to certain positions in the map following the polyline? Also, how can you do such smooth zooming? I have been searching this answer for days. Any suggestions is appreciated. Please help. Thank you!</p>