As BIM authors become more adept it quickly becomes apparent that a more hybrid understanding of 3D graphics is required. This new level of modeling takes the technical drafter down the road closer toward a visualization or animator role. Therefore a more specific description of Level of Detail/Development is required. (Each RPF or BIM Implementation needs to have a section defining LoD as it’s specifics mean different things to different people.)
It it important to note that Level of Detail and Level of Development are different things… Level of Development outlines what a model is authorized to be used for while Level of Detail describes the model’s graphical properties and goes together with Level of Appearance Quality (LoAQ).
Level of Detail in General
LoD1: Buildings are represented by their footprint or the roof outline with a constant height value. Inclusion of some density data or distances are possible.
LoD2: Buildings are represented by massing models.
LoD3: Buildings are represented by geometrically simplified exterior shell. Analysis of the materials is possible leading to an estimated ‘R’ value of the wall assembly & energy conservation performance.
LoD4: Buildings are represented by geometrically exact exterior shells.
LoD5: Building interiors are included.
Geometric Level of Detail (GLoD)
GLoD1: Buildings are represented as 2D surfaces inserted into 3D space.
GLoD2: Buildings are represented as simple 3D geometry.
GLoD3: Buildings elements that are 15cm and larger are included.
GLoD4: Buildings elements that are 5cm and larger are included.
GLoD5: Buildings elements that are 1cm and larger are included.
Level of Appearance Quality (LoAQ)
LoAQ0: No minimum appearance quality is specified.
LoAQ2: Buildings are represented as “shaded with edges” and indicates true colour. Includes shadows
LoAQ3: Building on the requirements of LoAQ2 but is expanded to include material mapping.
LoAQ4: Building on the requirements of LoAQ3 but is expanded to include full texture mapping (bump maps, transparency, luminance, reflectance…) to produce a photo real environment.
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