To demystify the concept of LOD BIM, let's explore this innovative approach in detail: LOD (Level of Development or Level of Detail), by definition in the field of BIM(Building Information Modeling*), represents the level of development of a digital model.
Because LOD has a major influence on the size and complexity of a BIM model, it's useful to distinguish between LOI (Level of Information), LOG (Level of Geometry) and to distinguish between several levels such as LOD 100, LOD 200, LOD 300, LOD 350, LOD 400 and LOD 500.
LOD can be interpreted as the degree of reliability of your BIM model. It's the degree to which an element's geometry and associated (non-graphical) information have been developed, including a certain level of LOD detail. We explain exactly how this works with a kiwi :
LOD = LOG + LAW
For this simplified representation of LOD = LOG + LOI, we've taken a kiwi as an example. Our LOD-kiwi is divided into LOG (geometry level) and LOI (information level) information.
LOG (Level of Geometry): Geometry level in LOD BIM
LL'extérieur, the visible part of LOD-kiwi, is the geometry level. It tells us about the appearance (geometry) of a product in the BIM model. The LOG, as in the construction model, gives us the level of geometric detail.
For example, EMCS 4.0 distinguishes 5 different levels or geometries, with LOG 1 representing a schematic or symbolic representation of a product, and LOG 5 a detailed, manufacturer-specific representation, including each LOD level of detail in BIM.
LOI (Level of Information) : Level of information in LOD BIM
The invisible, non-geometric part of the kiwi represents the LOI or level of information. In the LOD BIM example associated with the kiwi, these are non-physical aspects such as taste, color, smell, price and expiration date.
In BIM, LOI represents non-metric information, but rather the technical information of a digital model. Content with a high LOI, for example, contains manufacturer-specific information such as pricing and stock information.
Working with the LOD
Normally, the LOI and LOG develop as the project progresses. But there can be major differences between LOG and LOI: a component may have a symbolic representation, yet the information may be fully specified, including manufacturer-specific properties. Distinguishing between LOI and LOG helps to drive expectations and agreements, promoting efficiency and communication within BIM projects.
In general, as the project progresses, both LOI and LOG evolve. However, significant differences may exist between them. For example, a component may have a schematic representation (low LOG), but be accompanied by detailed, manufacturer-specific information (high LOI). This distinction between LOI and LOG is essential for directing expectations and reaching agreements, thus promoting efficiency and communication within BIM projects.
By taking into account non-graphical information as much as specific geometry and assembly details, the LOD BIM concept has been widely adopted, notably by the American Institute of Architects (AIA), which has defined each LOD level of detail to standardize BIM practices.
* In French-speaking regions, expressions such as "maquette numérique", "modèle BIM", or "maquette BIM" refer to a single concept, which is "Building Information Modeling".
Want to know more about LOD and how you can deal with it? Find out here how different levels of LOD impact BIM models.
