Computer-implemented method for identifying a geometry of a portion of an object in a three-dimensional digital representation of the object on the basis of reading a storage medium, on the basis of a computer tomography measurement, an optical measurement or a measurement by means of fringe projection or on the basis of a measurement method which outputs data that can be used to ascertain material interfaces of the examined object, the digital representation having a multiplicity of pixels, the pixels of the digital representation representing at least one material interface of the object, the method including the following steps: a) ascertaining the object representation, b) presenting the object representation on at least one display means, c) receiving at least one first user input, the user input specifying at least one first position in the object representation as a starting point, d) ascertaining a first set of pixels in the surroundings of the starting point, the first set of pixels representing the geometry of the portion in the region of the starting point, wherein the ascertainment of the first set of pixels includes the ascertainment of at least one first parameter of the material interface of the object at the location of the starting point, the respective first parameters of the material interface at the positions of the pixels of the first set of pixels corresponding to the at least one first parameter at the location of the first pixel, wherein mentioned correspondence of parameters is given when the parameters of the further pixels found are within a defined value interval around the parameter of the starting point, wherein the at least one first parameter is a curvature value that indicates how strongly a material interface of the presented object is curved at the position represented by the pixel, e) ascertaining a test geometry on the basis of the first set of pixels by fitting at least one geometric element to the pixels of the first set of pixels, f) ascertaining a second set of pixels in the surroundings of the starting point, the second set of pixels representing the geometry of the portion in the region of the test geometry, g) inserting the second set of pixels into at least one target set of pixels, h) displaying the pixels of the target set of pixels in the object representation on the at least one display means, i) receiving at least one second user input after displaying the pixels of the target set of pixels in the object representation on the at least one display means, the second user input indicating whether the displayed pixels correctly reproduce the geometry of the portion of the object, j) should the second user input indicate that the geometry is correctly reproduced, determining at least one dimension of the geometry and outputting the dimension, k) should the second user input indicate that the geometry is not reproduced correctly, repeating steps c) to i). a) ascertaining the object representation, b) presenting the object representation on at least one display means, c) receiving at least one first user input, the user input specifying at least one first position in the object representation as a starting point, d) ascertaining a first set of pixels in the surroundings of the starting point, the first set of pixels representing the geometry of the portion in the region of the starting point, wherein the ascertainment of the first set of pixels includes the ascertainment of at least one first parameter of the material interface of the object at the location of the starting point, the respective first parameters of the material interface at the positions of the pixels of the first set of pixels corresponding to the at least one first parameter at the location of the first pixel, wherein mentioned correspondence of parameters is given when the parameters of the further pixels found are within a defined value interval around the parameter of the starting point, wherein the at least one first parameter is a curvature value that indicates how strongly a material interface of the presented object is curved at the position represented by the pixel, e) ascertaining a test geometry on the basis of the first set of pixels by fitting at least one geometric element to the pixels of the first set of pixels, f) ascertaining a second set of pixels in the surroundings of the starting point, the second set of pixels representing the geometry of the portion in the region of the test geometry, g) inserting the second set of pixels into at least one target set of pixels, h) displaying the pixels of the target set of pixels in the object representation on the at least one display means, i) receiving at least one second user input after displaying the pixels of the target set of pixels in the object representation on the at least one display means, the second user input indicating whether the displayed pixels correctly reproduce the geometry of the portion of the object, j) should the second user input indicate that the geometry is correctly reproduced, determining at least one dimension of the geometry and outputting the dimension, k) should the second user input indicate that the geometry is not reproduced correctly, repeating steps c) to i).