Abstract: A method for measuring the 3D surface (15) of an object (14) in order to describe its form digitally. The object is pressed down on a membrane (6) so as to make an imprint to be transferred to a medium (4) below. Said medium can at the same time be exposed to a pressure for controlling the submerging therein. The imprint under the object (14) is scanned from below, through the medium (4), and particularly the transparency of the medium is registered in each scanning point to give a base for estimating the height up to the imprint and thereby the third dimension (z) of the surface (15). The pressure applied to a medium (4) can as an example be useful by the production of foot beds when said object (14) is a foot, together with a scanning result of an imprint where the imprint is made by an even pressure distribution at the downward-facing surface.