title: How would you find the height of objects given an image?
body: <p>This isn't exactly a programming question exactly. I just want to know what your approach would be to a common problem in Digital image processing. </p>
  
  <p>Let's say you have an image of a few trees in say jpg format. How would you go about finding the heights of each of these trees? The photo is the only input you have.</p>
  
  <p>I want to know the approaches you have not to code. So it doesn't matter if your answers are vague, or non DIP-ish. </p>
  
  <p>Small correction : 
  The height need not be the actual height of the tree. The height can be taken to any scale. But should be consistent to all objects in the pic.</p>