What Does LOD Actually Stand for in BIM? (And Why People Get It Wrong)

If you have spent any time around a BIM project, you have heard the term Level of Development (LOD) thrown around with reckless abandon. Ask ten individuals in a room what LOD means, you'll likely get ten different answers. In fact, it is one of the greatest sources of confusion across the AEC world, and it can have a real impact on your ability to communicate on a project.

What Is the LOD Full Form? BIM Level of Development

LOD stands for Level of Development, not Level of Detail (a common misconception that is easy to understand). As you may be able to tell from the phrasing of these terms, the proper term has more to do with the extent of development of a 3D model element rather than the amount of detail.

Why Does Everyone Assume It's "Level of Detail"?

As mentioned, most who are unfamiliar with the distinction between the two concepts will mistakenly believe that Level of Detail and LOD refer to the same thing. Detail is the simpler-sounding phrase, and it is much more intuitive to think of a 3D model's "level" in terms of its visual complexity than its reliability for use on a project. In other words, we think of a model's level in terms of how much geometry or texture is put into an element, rather than how much we can rely on it to represent reality accurately.

What's the Difference Between the Two Concepts?

Level of Detail refers to the amount of visual or graphical information that a 3D model element contains or its percentage of completion. Level of Development, on the other hand, refers to how reliable a piece of information is for use by the project team. The difference between the two phrases can best be summarized as one being an input to a 3D model and the other being an output of one.

How Does the Difference Between the Two Terms Impact Me?

If your contractors assume that a model element has been developed to a higher level than it actually has, it could cause issues for a project. Quantity takeoffs, assumptions made about the cost of a project, and potential clashes that need to be resolved in the field could be impacted. The BIM Level of Development specification attempts to standardize the language of 3D modeling and ensure that each party involved with a project has a shared understanding of the information within a model.

Where Does This Standard Come From?

This standard, which was established in 2008 by the American Institute of Architects, is kept up to date by the BIM Forum LOD specification and is used throughout the industry by professionals.If you want more information on the full scope of the Level of Development specification (and an explanation on how a model element can have multiple levels of development simultaneously), you should read this post all about BIM Level of Development from LOD 100 to 500, which goes into more detail about the standard as defined by the AIA and BIM Forum.Understanding the difference between the two terms Level of Development and Level of Detail is crucial on a BIM project.