Abstract: A three-dimensional component (1) with an external geometry and an internal geometry is digitized in a destructive method. Three-dimensional marking bodies (30) are applied to the outer surface of the body (1). The external geometry of the component (1) with the marking bodies (30) is then digitized using a suitable method and a reference data record is created. The component (1) is disassembled into segments so that all contours of the internal geometry are exposed, after which these segments are digitized. The digital data records of the segments are finally correctly aligned in space and to one another with the aid of the reference data record of the component (1) with the marking geometries (30) and combined. The method is particularly suitable for digitizing components (1) made of materials which are difficult to penetrate with radiation and/or have a high wall thickness.