Semiautomatic Parametric Modelling of the Buildings on Town Scale Models

摘要

This article presents the semiautomatic parametric method we have conceived and developed for the 3D modelling of town parts of physical town scale models. On one hand, most photogrammetric and lasergrammetric methods do not use parametric models to assist the 3D modelling. On the other hand, architectural parametric models do not use automatic photogrammetric and lasergrammetric methods to position and dimension the parametric models. This article brings both techniques together to provide an entirely automatic system for the 3D modelling of the buildings of physical scale models. In a previous experience, our method was not completely automatic and not parametric. This led to a time-consuming process and some difficulties for the handling and adjustments of the buildings arose. Town scale models realised between the 16th and the 19th centuries are used as an application of our method. These physical models are made out of wood and paper with a scale of around 1:600. From textured meshes obtained from pictures with 123D Catch software, we automatically extract the relevant features. We also identify the type of parametric building before determining the parameters' values to be assigned to the building model. Around 95% of the scale model's buildings are of the most common types of building and can be easily modelled with parametric components. The remaining are unique and/or complex cases that can be treated as before or described by a specific parametric model added to the library by the user. Indeed, the parametric models are described by the user in a specific part of the software, so that the library is easily extendable by a non-computer science developer.