1. A method for generating a simplified geometric model comprising a frame and lenses of a real pair of spectacles, the simplified geometric comprises a predefined number of surfaces and normals thereof, taking as an orientation of these normals an exterior of a convex envelop to the real pair of spectacles, the simplified geometric model been obtained in a phase in which: a set of views of the real pair of spectacles to be modeled is produced, with different angles-of-view and using different screen backgrounds with and without the real pair of spectacles, images of the real pair of spectacles are obtained at high resolution according to V different reference orientations; the simplified geometric model is constructed, consisting of the predefined number of surfaces and their normal beginning with a non-dense surface mesh and using an optimization algorithm that deforms the model's mesh so that projections of its silhouette in each of the views best match the silhouettes detected in the images; and wherein the number V of reference orientations is at least equal to nine.