LOD is more than just an acronym for levels of detail; it's the methodology that precisely defines the degree of maturity of a BIM (Building Information Modeling) model. It is a common language that makes it easier for all stakeholders to understand and manage a project. At various stages of the construction process, from the conceptual phase to physical completion, LOD plays a key role. We tell you all about it.
What is LOD?
LOD, an acronym for Level of Detail, has been defined by the BIM Forum. The term refers to the segmentation of a
3D model
the LOD challenge? To standardize the way in which the geometric information and attributes of a BIM model take shape throughout the design and construction stages of a project.
Are Level of Information and Level of Detail different?
The LOD does not denote a degree of maturity; it responds to a need to
precision
. A low LOD is not to be confused with a lack of information. In fact, the term Level of Information (LOI) is commonly used. It should be noted, however, that LOI is not intended to replace Level of Detail
non-graphical information attached to 3D objects.
By combining LOD and LOI, we obtain the so-called " Level Of Development ". Abbreviated "LOD's", it refers to both the geometric and informative levels of detail in the digital mock-up.
To remember
Level of Detail + Level of Information = Level of Development
LOD levels
Depending on the specifics and needs of each project, a 3D model encompasses various objects. These represent :
the general structure of the building, both inside (floors, walls, posts and beams) and out (walls, doors, windows and roofs);
architectural trades (doors, windows, partitions and roofing);
networks and terminals (HVAC, electrical, plumbing and SSI);
industrial equipment (machines, production lines).
As you move up the LOD levels, you increase the geometric detail of the objects and the information they contain. Each object type follows a standardization process that enables the software to adapt to the level of detail required for the 3D model's components.
The LOD hierarchy
The continuum of LOD levels can be broken down into several stages, each providing an additional layer of information to the model. There are 6 stages:
LOD 100: conceptual building modeling - used to visualize the approximate shape, size and position of elements, but without geometric precision or detailed information (in 2D);
LOD 200: more precise geometric information included in the BIM model - the shapes, sizes and approximate locations of the elements accompanied by basic information on their composition;
LOD 300: constructible level of detail - elements shown with exact dimensions, specific shapes and detailed information on their manufacture and installation;
LOD 350: intermediate between LOD 300 and LOD 400, provides element-specific information - manufacturing details, connections and installation information;
LOD 400: individual building elements used for site coordination and conflict management - specifications, exact dimensions and construction details ;
LOD 500: " as-built " information corresponding to the precise installation and construction details carried out in the completed building.
The level of detail of the LOD: a key to precision
At the heart of a BIM digital mock-up, several players with different roles are involved at different levels. Each responsibility is assigned to an appropriate level. The objective behind this work? To meet the
need for organization
architectural projects! And since all the necessary information is available, the LOD can be used in several phases:
design,
construction,
operation.
If we take the example of a simple door handle: by documenting it down to reference detail, if it needs replacing, the process is facilitated. The BIM model is therefore an invaluable tool for anticipating such changes and facilitating their execution.
Combining LODs
Note that not all mock-ups require the same level of detail. It is by defining specific levels upstream of modeling that it is possible tooptimize the costs and production times of a mock-up.
The example of network and terminal detail
When modeling networks (electrical, HVAC, plumbing or SSI), LOD 200 or 300 is often used, rarely LOD 400.
In order to guarantee a usable final rendering in every phase of your projects, it's essential to carefully study the needs of all the stakeholders involved in the digital building model. Want to find out more about managing levels of detail in BIM projects?
