Abstract
In geometric modeling two main technologies have been successful and are continuing their development: solid modeling and surface modeling. These techniques are still used separately while being complementary in their advantages: a solid modeler is able to describe objects with a clear distinction between inner and outer parts, whereas a surface modeler is better suited in the description of free form objects, but leaves the model validity to the user responsibility. The integration of the two technologies is therefore an important topic of the current research in the field. This paper presents a new technique to perform booleans with trimmed curves and surfaces; such a technique is not based on point set classification, but exploits geometry orientation; this makes it able to deal with non closed topologies, thus extending the classical concept of boolean operators. According to this approach several valid operators can be defined, which behave like booleans in the case of closed topologies but differently with non closed ones.