A paper, a description of a software application is given, which allows to generate tridimensional models of buildings, directly inside a geo referential context, following a parametric approach, in which the volume of the building is put in direct relation with forces/law bonds emerging from the urban context. The user is, therefore, able to interactively operate within a project process, in which, by changing the parameters values and by verifying in real time, the results of the changes, he/she is able to evaluate all possible infinite scenarios. The system, thought for Trentois (Italy) urban context, may also be applied on other cities.