title: Kinect intrinsic parameters from field of view
body: <p>Microsoft state that the field of view angles for the Kinect are 43 degrees vertical and 57 horizontal (stated <a href="http://msdn.microsoft.com/en-us/library/jj131033.aspx">here</a>) . Given these, can we calculate the intrinsic parameters i.e. focal point and centre of projection? I assume centre of projection can be given as (0,0,0)?</p>
  
  <p>Thanks</p>
  
  <p><strong>EDIT: some more information on what I'm trying to do</strong></p>
  
  <p>I have a dataset of images recorded with a Kinect, I am trying to convert pixel positions (x_screen,y_screen and z_world (in mm)) to real world coordinates. </p>
  
  <p>If I know the camera is placed at point (x',y',z') in the real world coordinate system, is it sufficient to find the real world coordinates by doing the following:</p>
  
  <pre><code>x_world = (x_screen - c_x) * z_world / f_x
  y_world = (y_screen - c_y) * z_world / f_y
  </code></pre>
  
  <p>where <code>c_x = x'</code> and <code>c_y = y'</code> and <code>f_x, f_y</code> is the focal length? And also how can I find the focal length given just knowledge of the field of view?</p>
  
  <p>Thanks</p>