In a perfect world there would be one 3D model that is sufficient for all aspect of a building throughout its life, but currently is not the case. In most families there are more than one purpose to serve, often with conflicting requirements.
Families need to be modeled simply to display properly on council submission drawings. On a 1:100 drawing, 0.35mm thick lines will merge if they are modeled 35mm apart. Symbols may be embedded for views like electrical layouts.
Families also need to be modeled in detail for Virtual Reality as well as still, panoramic and movie renders. In addition they should also be able to be 3D printed for manufacture or modelling. Such detail typically displays horrendously in plan, elevation and section views used for council submission. Then again, excessive detail will even not display well in Virtual Reality (too many polygons to process).
The AEC (UK) BIM Technology Protocol, Version 2.1.1 of June 2015 discusses families in terms of their Level of Detail (LOD).
Typically families will conform to LOD 3 – Generic
- A generic model, sufficiently modelled to identify type and component materials.
- Typically contains level of 2D detail suitable for the “preferred” scale.
- Dimensions may be approximate.
The following piece of advice should be carefully noted:
“When in doubt, users should opt for less 3D geometry, rather than more, as the efficiency of the BIM is largely defined by the performance of the components contained within.”
If you have any questions regarding your modeling of families or their management within your project, don’t hesitate to give Micrographics a call so we may advise you appropriately.