title: Crowd video real time object recognition and collision detection library or tool recommendations
body: <p>We need to be able to analyse an HD video of a crowd scene from above (think train station) and be able to detect all moving objects and perform collision detection. A virtual object will effectively be superimposed on the image and must respond to the real objects. This needs to happen in real time.</p>
  
  <p>Ideally I am looking for a library that can be consumed from C# to do this. This is way out of my comfort zone so I am just looking for some pointers as to whether this is an easy or infeasibly difficult problem and what tools would be up to the job. Is OpenCV suitable for example?</p>
  
  <p>If there are performance limitations on how many objects can be processed what would these be?</p>