One common data source are 3D faces. You can always combine multiple data sources in order to build a surface, however 3D faces provide the benefit of exactly replicating the triangulation from the 3D faces.
Surfaces can be built from points and breaklines. In these cases, the software reads layers of data in the drawing - users select the layer/s containing AutoCAD points and layer/s containing 3D polylines (or 2D polylines at elevation).
Toggle display lets you turn on/off multiple surfaces - display tirangles, major or minor contours.
Surfaces volumes lets you select any two surfaces and output cut and fill volumes, including applying cut and fill factors.
As well as generating reports with the volume outputs, you can also create a volume surface from the comparison. The boundary will need to be applied to the volume surface that is created.