title: Finding distance between camera holder and wall using optical flow
body: <p>Is it possible to exactly determine the distance between a wall and a smart card holding person who is walking at normal speed ? There is just a single camera in the smart phone. Can it be done through optical flow ? I am asking that because on google search I found out that calculating distance can be misleading . Read the comment of Peter Meijer <a href="http://www.linkedin.com/groups/How-get-distance-information-from-37629.S.46330803" rel="nofollow">here</a>.</p>
  
  <p>Also, I wanna know is there any other option that I can have to calculate distance traveled by walking person given only resource I have is a smart phone with camera and accelerometer . Just mentioning algorithms or giving links would be suffice. </p>
  
  <p>Information available with me :-</p>
  
  <ol>
  <li><p>Maximum distance of the camera from wall</p></li>
  <li><p>Acceleration from Android accelerometer to find out approximate
  velocity of user</p></li>
  </ol>
  
  <p>Please comment if I am unclear in asking my question.</p>