Thank you David for directions.
Generally I need to calculate volume between two triangulated surface A and B.
Requirements:
1. Each surface has different shape and size.
2. Surfaces can intersect (cross) each other (so the volume with sign +/ should be considered)  the surfaces can form something like "X" sign.
3. The volume between surface is limited.
What does mean word "limited" in point 3. Let me explain. When you make projection on XY plane of two surfaces A and B, then we can calculate two 2D convex hulls (for surface A and B). Then volume should be calculated based on the region formed
from intersection of convex hull A and convex hull B.
Have you some direction how to calculate the volume taking requirement into account?
(I can describe problem in details and send you an email  if you agree).
Thanks you for earlier reply!
Best regards
Simon
