1. A method for measuring mechanical workpieces having a defined rotationally symmetric structure, the method comprising the steps of: providing a radiation source for generating radiation; providing a detector array for receiving the radiation, said detector array defining a two-dimensional imaging plane; positioning a workpiece between the radiation source and the detector array, so that the radiation penetrates the workpiece before it impinges on the detector array; moving the radiation source and the workpiece relative to one another in a step-by-step fashion; generating a number of two-dimensional images of the workpiece by means of the detector array for a plurality of movement positions of the workpiece; and computing a three-dimensional image of the structure from the two-dimensional images, wherein the step of computing comprises: detecting a high-contrast transition, which may correspond to edges of the structure, in said two-dimensional images; registering points at said high-contrast transition from at least two two-dimensional images generated at two different movement positions; and determining a three-dimensional geometric equivalent body using the registered points; and comparing said equivalent body to a predefined nominal structure; wherein the geometric equivalent body only parameterizes said rotationally symmetric structure.