Object-based parametric modelling

Object-based parametric modelling is the paradigm beneath BIM: digital objects — organised into families or classes — whose geometry and properties are driven by parameters, rules and constraints rather than manipulated by hand. It originated in 1970s–80s manufacturing and became the engine of BIM.

In practice a parameter is a value that reshapes geometry the moment it changes. Objects are defined by relational rules — alignments, distances, angles, constraints — and by conditional "if-then" logic, so that editing one value regenerates the dependent components automatically. The objects also carry non-graphical data (materials, performance) and emulate the behaviour of real elements — doors, walls, ducts.

This is the technical foundation that separates BIM from drafting. In CAD you manipulate static lines with no intelligence behind them; here the model is generated by data-driven logic, components reference external information, and clash checking is intrinsic — the difference between drawing one object and defining a whole class of them. It rests on the 3D model and is what makes semantic enrichment possible. In Italian it is modellazione parametrica a oggetti.