String volumes are ideal for quickly calculating spoil heap quantities. However, unless you know that the ground is one flat plane then only use this as an estimate as this won't be accounted for. Ensure that the Stockpiles have unique string numbers.
In the situation where there’s no available reference surface, an Inclined Plane can be used. The points in the reference string will be used to calculate a best-fit plane to which triangle will be projected to.
This is the preferred way of calculating volumes, using triangular prisms.
The convention is that Heights Above a Reference Surface are +ve (Material/Cut) and those Below are –ve (Void/Fill). This may appear obvious when written down like this but it may cause problems when working with real models.
This method means that the ground level does not need to be even as n4ce uses triangles from the DTM instead of a flat plane. This means that calculations are more accurate and precise compared to String Volumes. However, this method requires more time and effort as each stockpile needs to have an individual group created and associated with it. In addition to this, the more point n4ce has for that specific data than the more accurate the volume becomes.