In order to determine the thickness of the final coating, it is necessary to have the reference geo-referenced surface of the first phase coating. It can be supplied in dxf or dwg format. The Figure illustrates an example of a spritzbeton intrados surface; the density of the points can be varied according to the needs of the project. Alternatively, the geo-referenced section of the first phase cladding can be supplied, again in dxf or dwg format, upon progressive request. Once the surface of the spritzbeton intrados is known, it is possible to calculate very accurately the volume of concrete necessary for a given casting at a given progressive, with the advantage of being able to then order the exact quantity of concrete, or in order to check that the quantity of concrete poured is correct.