~ Level of Development or Level of Detail
The subject LOD tries to define something about the phases of enrichment of information in a construction process. Originally, five levels are mentioned (LOD 100 to 500) on which a BIM can be located.
There are many misunderstandings and discussions about the term LOD. LOD is sometimes interpreted as Level of Detail rather than Level of Development. In general the concept of Level of Development is used. There are important differences. Level of Detail is essentially hów much detail is included in the model element. Level of Development is the degree to which the element’s geometry and attached information has been thought through – the degree to which project team members may rely on the information when using the model.
In essence, Level of Detail can be thought of as input to the element, while Level of Development is reliable output.
A formal definition of the LOD levels has never been set. Different initiatives all over the world have created their own dialect of LOD, or a different approach for model progression and information levels. As a result of this, many people make assumptions. If those assumptions are not matched in a project, misunderstandings arise.
In recent years, the LOD definition from BIM Forum seems to be the de facto standard that is used worldwide.
It is important to agree in advance which information should be modeled and when. In order to register this, each party must know (and realize) which information they need as a minimum in order to do their work. This is a matter that turns out to be quite difficult in reality. The BIM Execution Plan Generator tries to facilitate this process.