Level of Detail

(See also Level of Development for comparison)

This is the amount of information and geometry provided by the content author or other project participant. There can always be a higher level of detail in a project model than what is realistic to be used by others in a downstream workflow but as the Level of Detail increases so does the amount of data stored and manipulated.

As an example ARUP propose their level of detail definition is based on an amended version of the guidelines set out in the AEC (UK) BIM Standard for Autodesk Revit.

The AEC(UK) document uses a chair as an example, and gives the following description of the grades…

Component Grade 1 – Concept

  • Simple place-holder with absolute minimum level detail to be identifiable, e.g. as any type of chair.
  • Superficial dimensional representation.
  • Generic in terms of manufacturer information and technical data.
  • Created from consistent material: either “Concept–White” or “Concept–Glazing”.

Component Grade 2 – Defined

  • Contains all relevant meta-data and technical information, and is sufficiently modelled to identify type of chair and component materials.
  • Typically contains level of 2D detail suitable for the “Preferred” scale.
  • Sufficient for most projects.

Component Grade 3 – Rendered

  • Identical to the Grade 2 version if scheduled or interrogated by annotation. Differs only in 3D representation.
  • Used only when a 3D view at a sufficient scale deems the detail necessary due to the object's proximity to the camera

MEP Level of Detail Definition as suggested by ARUP

The 3 AEC (UK) grades are appropriate for geometry, since there is too big a jump from grade 1 to grade 2, and that grade 3 should not be reserved just for rendering. For information (metadata) ARUP believe that an extra grade is necessary

Grade Geometry Information Indicative image
0 None - N/A None - N/ANone - N/A
1 Simple place-holder with absolute minimum level of detailMetadata restricted to object classification (e.g. Mechanical Equipment > Gas Fired Boiler) Image 1
Superficial dimensional representation. (including space for access/maintenance)MEP Connectors optional
Materials that represent the (sub)discipline, e.g. red for heating plant, blue for cooling plant, green for ventilation plant, purple for domestic water plant and yellow for electrical plant. Access space shown as transparent material
2 Typically contains minimum level of 3D detail suitable for the “Preferred” scale, with 2D embellishments where necessaryContains design performance related meta-data (e.g. Max Heat Output, Min Heat Output)
Materials as concept Connectors with correctly defined configuration, located in appropriate positions on plant
3 “Shrink-wrapped” manufacturers model – key functional components modelled, hangers and supports modelled. Fixings, internals etc. not modelledContains all specification meta-data, where necessary in the form of hyperlinks to manufacturers equipment sheets
Materials as manufacturer
4 n/a Meta-data extend to (possibly) include commissioning records, maintenance records, client specific FM data