Method and apparatus for determining a contour of a frame groove

An apparatus for contactless determination of a contour of a frame groove in a rim of a spectacle frame, the apparatus comprising:

• an illumination device configured to illuminate the rim of the spectacle frame;
• an image capturing device configured to capture a plurality of images of the illuminated rim from different predetermined perspectives;
• an image evaluation unit configured to evaluate the plurality of captured images, to determine the spatial curves describing the frame groove on the basis of the evaluated images, and to determine the contour of the frame groove based on the spatial curves,
• wherein the illumination device is configured to illuminate the rim simultaneously along an entire circumference of the rim with directed illumination;
• wherein the evaluation of the plurality of captured images includes recognizing portions of the spectacle frame contained in the captured images and an assignment of each portion contained in the captured images to a respective surface element of the frame groove based on a brightness and/or shading of the respective portion,
• wherein recognizing the portions includes:
• a rim segmentation;
• a detection of edges which bound the portions and surface elements within the segmented rim, with preference given to edges extending virtually parallel to the rim;
• and
• a completion of the edges with a first optimization method in which a cost function is minimized;
• and
• the image evaluation unit is further configured such that the determination of the spatial curves includes:
• to determine spatial points, which describe the frame groove and through which the spatial curves extend, based on the surface elements, the spatial points being located on edges which bound the portions and the surface elements;
• and
• to determine a relative position of the spatial points in space by triangulation, the triangulation being carried out collectively for all spatial points of a spatial curve of the plurality of spatial curves and a criterion of a smallest distance as an optimization goal in the form of a term of a cost function is included in an iterative optimization with a second optimization method.