Thanks for your answer. Let me explain my problem. My explanation was really bad. I was in rush I apologize. I measured GCP (with GNSS GPS) to make my 3D model accurate. I have very accurate 3D model of surface in coordinate system. But other thing is. I have project from designer in CAD (microstation). This project is on the same coordinate system as 3D model. But points from this project are (let's say) under the ground. Level of these points is under the ground in real world And I need to know volume, how much ground we need to remove (dig) to reach the project level. I did not find software to be able to do this. Using points and measure volume above these points. It is difference between my 3D model and surface made from points in Microstation. We found the way throug microstation. It works but it is not accurate. If you have any tips, it could also help to your company to do volume calculations. I am going to check it and work for it. Many thanks for your answer.