# About the descriptions of base surface setting.

Hello
I am wondering about the base surface setting part, and I am confused about the descriptions from the website as shown below:
Triangulated: Connects all the vertices and triangulates the volume above and below the base surface. Recommended option when the entire boundary of the stockpile is visible and the surface is relatively flat.
Fit Plane: Fits a plane to the vertices, so that all vertices are at the minimum distance from the base surface. Recommended option when the entire boundary of the stockpile is visible and the base surface is a hard surface, a slop or flat with the same altitude.
First at all, what does the ‘’vertices’’ mean? Is that means the green points which I made for calculating the volume? Does the vertices setting influence the form of base surface is?
Secondly, what is the difference between the Triangulated and Fit Plane? What does the ‘’ the volume above and below the base surface” and ” so that all vertices are at the minimum distance from the base surface “mean? Could you use the picture or specific example to show how they work.
Thirdly, I found the volumes are diverse that depends on the amount of green points, is this caused by the base surface setting?
Finally, in my case, I want to obtain the volumes of crater each time (The ground is compacted by dropping a heavy weight repeatedly so becomes the concave crater on the ground). In this case, which base surface is suitable for this case.
Sorry for many questions, Thank you so much.

Hello,

The word “vertices” refers to the green points of the polygon that you draw for the volume calculation.

The base surface is defined according to the definition of the vertices of the polygon. If the base surface is defined as Triangulated, the vertices of the base surface will be the same as those drawn; if the base surface is defined as Fit Plane, the vertices of the base surface might differ from those drawn and the base surface will be the plane interpolating the drawn vertices, with the least squares principle (at the minimum distance).

I can add some screenshots I got when calculating a volume on the Cloud, as there you can visually see the base surface (in transparent color). I have created a volume that starts on the ground and intersects a stockpile.

If you evaluate the volume with the Triangulated method you will obtain something like this:

If you evaluate the volume with the Fit Plane method you will obtain something like this:

The red area represents the cut volume, which is the volume that is above the base surface, while the blue area represents the fill volume, which is the volume that lies below the base surface.

Relatively to your project with the crater, I would suggest drawing the base surface along the crater and using the triangulated method. The fill volume will tell you the amount of volume contained in the crater.

Let me know if it’s clear.

That is clear.Thank you so much.