Multi-scale geometry in civil engineering models: Consistency preservation through procedural representations

For the planning of large infrastructure projects, such as tunnelled inner-city carriageways, completely different scales have to be considered – ranging from the scale of several kilometres for the general routing of the carriageway down to centimetre scale for the detailed planning of track nodes. However, today’s planning software hardly supports multi-scale approaches. The paper presents a new methodology for creating and storing multi-scale geometric models for infrastructure projects which explicitly defines dependencies between the individual levels-of-detail (LoD). These explicit dependencies allow for automated consistency checks and even automated consistency preservation. The methodology relies on parametric modelling technologies, including the use of dimensional and geometric constraints for defining flexible 2D sketches, as well as the procedural definition of complex 3D models through the sequential use of geometric operations such as extrusion, transformation and Boolean operations. Applying the methodology presented in this paper ensures that modification on coarse LoDs are automatically propagated to all finer LoDs, thus providing means for an automated preservation of consistency and, at the same time, significantly reducing the effort required for re-elaboration.