title: Algorithm for calculating the volume of the part of point cloud
body: <p>I am taking part in the project studies associated with clouds of points. </p>
  
  <p>We have to create a web application. Whose task will be displaying point cloud  from .ply file. And then select an area and calculate its volume. The algorithm of counting the volume is to be implemented in C ++. The only things we have is a file in .ply format and file with the XYZ-coordinates of all points. The cloud of points we get, is generated from a picture taken by a drone. For example, it is a cloud of points representing a mountainous area . Our task is to be able to select such one mountain and calculate its approximate volume taking into account an error +/-. The measurement does not have to be perfect but it has to be even close to the real volume of mountain. The volume has to be calculated from the flat surface at the lowest point of the mountain.</p>
  
  <p>I have two questions for you.
  -First, could you give me a clue, link or anything that would help me to find such an algorithm and the reasons why he is the best.
  -Second, do any of you have idea what would be the best way to select some area from the rendered  point cloud?</p>
  
  <p>I was looking for this information . But I can not find anything that would be useful enough to use it in our project. Any tip or a document on the subject would be very useful ;)</p>