There has been much discussion lately on the use of Building Information within the heritage sector. Through our sister company…
There has been much discussion lately on the use of Building Information within the heritage sector. Through our sister company Digital Surveys we have over 30 years’ experience of carrying out surveys for historic building to the English Heritage Metric Survey specification.
Trying to convert these surveys into BIM has a number of Inherent issues. First and foremost BIM software such as Revit, ArchiCAD or Vector works is not designed to model old buildings.
Old buildings have walls which are out of plumb, deformation, bowing, unlevel and uneven floors and a host of shapes and items which are unique to each property.
This makes modelling them very challenging, although not impossible. When looking at having a BIM survey carried out of a historic building a clear scope of work needs to be identified clearly stating modelling tolerances.
When the building is scanned, reality is captured creating an exact scale recreation of the environment. To convert this data to a BIM, an experienced modeller must interpret the scan data and best fit standard shapes and families of components to the point cloud. This is where a highly skilled modeller is essential and a lot is down to the modeller’s interpretation of the data.
If budget was unlimited then it would be possible to accurately model even the most complex buildings, however it would be incredibly time consuming and labour intensive. Also a lot of the ways of modelling items require hacks to get the software to accurately show something that it assumes should be straight and orthogonal. This means that the models become very heavy and unusable in many of the ways and benefits that BIM provides.
Until the software catches up with required functionality there needs to be half way point that combines the best use of BIM with the accuracy required from traditional surveys and mediums.
This could be that the BIM is use to accurately record the quantities of items in a building, for example windows, doors columns etc. This way all the benefits of quantity take off and scheduling can be utilised. However when more accurate information is required then the model links to detailed 2D drawings, line work, ortho photos etc.
There is still some way to go before the integration of historic buildings into the BIM workflow is perfect. The onerous is now on the software companies to make the required functionality available to accommodate these ever more complex demands.
eBIM™ is Digital Surveys dedicated building information modelling solution for existing buildings and infrastructure. We operate nationally and across Europe from offices in London and Newcastle.