reverse architecture

Reverse architecture1) is a term used to describe the art of building a digital mockup2) from an existing building. This can be compared to reverse engineering but is applied to architecture. The production process of a digital mockup might be based on geomatician point clouds –Lidar / 3D scan– or on 2D documentation if it includes a sufficient set of plans, sections and elevations. 

The purpose of reverse architecture is to simulate a spacial or structural transformation. The pertinence of a digital mockup in the planing process, is the algorithmic extraction of 2D plans plans wherever necessary for the transformation project. 
The mock-up consists of objects or entities that include geometry and alphanumeric information. The entities on one hand must be structured in order to produce plans and sections according to the norms in force (i.e. in Switzerland SIA 400). 

On the other, they must contain accurate alphanumerical information (i.e. the entity wall has the information: made of bricks, is structural, resist to fire for 90 min…). In a similar way to the algorithmic extraction of geometry form the mock up, the information according to a specific model view definition will differentiate the entities from another i.e. to generate a fire security plan (see example of algorithmic generated fire security plan) or for the civil engineer to simulate a structural transformation.

1) The term of reverse architecture was used by by R.L. Krikhaar (Amsterdam 1997, ISBN: 0-8186- 8013-X) referring to software maintenance. This term was used by the team Vallorbe Gare to describe one of the three phase of the eponym pilot project (see exemple project below).
2) A digital mockup (maquette numérique in French) is to be differentiate from a 3D digital model as this last one only contains geometry.