Object segmentation in meaningfull parts is an important research topic as these have become a part of many mesh and object manipulation algorithms in computer graphics, geometric modelling and computer aided design. In particular, tasks that were before realized by experts are more and more assumed by people without particular formation in geometric or computer graphic problems. So there is a need to have some ergonomic tools that have expert know-how while user keep control on specific constraints to its particular application. Here, we present how for segmentation purpose we model expert know-how and two algorithms that can be used to make segmentation task. One is generic and the other is specialized for glasses segmentations.