BIM stands for – building information modelling – in addition to 3D CAD model being a spatial representation of an object, BIM models add certain information, one could call a database. Each element is defined (walls, windows, floors etc.), and the model is a parametric result combining all of those elements. 2D plans, sections and elevations can be generated automatically from any defined position or direction.
BIM models may also contain other than structural elements – mechanical, electrical, plumbing installations, etc. commonly referred to as MEP.
Exchanging data between BIM formats proved to be changeling and it could cause some problems, We can create native BIM models in two leading formats, namely Revit (from AutoDesk) and AECOSim (from Bentley Systems).
Same as on the ‘standard’ models deciding on the level of detail is crucial.
While the BIM process in its conception was a tool for new construction, as we are all aware a significant percentage of projects are concerned with the redevelopment of existing building stock. Throughout the life cycle of a project 3D laser scanning becomes a key application. The foundation of any BIM process is the data that the design will be built upon. An appropriate scan to BIM model will provide the basis of this foundation.
At 3Deling we are highly experienced in the collection and processing of accurate point cloud data. 3D parametric models can be produced directly from the point cloud, typically in Revit format, however, if required, we can deliver the models in Bentley AECOsim.
Based on the model 2D sheets can be produced at any specified location for plans, sections or elevations. It should be noted that these sheets will not produce the same level of information as would normally be supplied on a typical 2D survey, however, should it be required, we can enhance this information manually if specified at the outset.
As with any survey data, the specification is all important. In the BIM environment, due to an almost infinite number of variables available, this becomes critical. We will work with our clients to define specification at the outset. Due to the collaborative nature of the BIM process, it may be necessary to consult a number of key stakeholders within the project before producing a definitive specification.
THINGS TO CONSIDER:
LOD (Level of Detail) How many details do you need in the model? Think about what the plan for the building is. You may need high detail level on a retained facade, for example, but low detail level on internal partitioning if all you require is to quantify the volume that will be removed.
LOI (Level of Information) How much intelligence do you need from the modelled elements? Be aware that in an existing structure the surveyor may be unable to access all fragments of the building, and will not have an in-depth knowledge within all related disciplines. Discuss any possible limitations at the outset.
Which coordinate system will be used? This is often overlooked but can be critical. Decide at the outset, protect it on site, ensure that all stakeholders are aware of it, and use it.
Basepoint of the model. Again, often overlooked but difficult to change later. Decide on a location and ensure that all stakeholders are aware of it. This will make a federation of models from the various disciplines much easier if its consistent from day one. BIM is a collaborative process. To gain the maximum benefit of it, in terms of time and cost savings, just as with any other building, it is important to start on firm foundations.
THINGS WE DO TO KEEP AS-BUILT BIM MODEL EASY TO USE:
All families created from the point cloud have a word “SURVEY” as a prefix in their name. This indicates that particular element was created from the point cloud data only.
Our models are positioned with real-world coordinates in mind, but we use a Project Base Point to reposition each building to local coordinates or to match some particular orientation (like from the existing drawings).
All models are created in collaborate mode. We can provide both detached (local) model as well as central model. We can continue to work on received central file and send it back for synchronisation.
All elements or areas that are not possible to recreate from the point cloud are marked up or described as assumed (by project parameters, scope boxes, dedicated set of section views or in any other way suitable for our client).
Special set of filtered views are provided in every model to indicate that certain elements in the model require clients’ attention.
We always take into account the client’s’ requests.
We use the same set of shared project parameters to provide extra survey information within the model.
Project examples – BIM models:
Central London mansion – BIM modelArchitecture & Constructions, BIM, Registered Point cloud
As-Built verification and BIM modelling2D CAD documentation, Architecture & Constructions, BIM
Drone Survey of larger rural estateBIM, Truviews, Urban planning
Milton KeynesArchitecture & Constructions, BIM, Registered Point cloud
Historic Elevation in PłockBIM, Heritage, Orthophoto, Registered Point cloud
Villa Zgorzelec2D CAD documentation, Architecture & Constructions, BIM, Truviews
Newcastle School2D CAD documentation, Architecture & Constructions, BIM, Registered Point cloud, Truviews
Manchester LibraryArchitecture & Constructions, BIM, Panoramas walk through, Registered Point cloud, Truviews