When bringing an existing real-world building or structure into the digital environment, no software solution is perfect. In general, the BIM modelling tools are designed for use as design origination tools rather than tools ideally suited to modelling the as-built condition. Typically this means that walls are never straight, parallel or plumb, slabs are never level, perfect or near perfect right angles are rarely encountered.
Inevitably that means that the modelling process is a matter of creating elements which are a ‘best-fit’ to the data captured on site.
However, here at Benchmarq we maintain an ongoing programme of development of in-house tools for BIM modelling, not only for our own benefit but also in the interests of delivering a much more usable 3D model to the Client.
For example, in a structure such as this one, if walls which are not perfectly parallel to one another are modelled with absolute accuracy the resulting element will not report its location to adjacent elements. In simple terms, it means that distances between adjacent walls are not automatically annotated/dimensioned, meaning that the 3D model is rather less usable to the Client than it should be.
If the Client is planning to use the model as the basis for further design development, this can create a significant productivity issue.
Our solution has been to develop a series of in-house routines which consider how ‘out-of-parallel’ walls actually are and, within tightly controlled (mm) tolerances, generate a model where the walls are parallel and therefore can be automatically annotated with the distance to adjacent walls.
The images below illustrate the point: