The technology of information modeling is being used more and more actively. However, for its full use, not only special software tools are needed – we also need a common language that will allow customers, designers and contractors in the field of architecture and construction to understand each other. This language is the level of detail – LOD and LOI.
There is some terminological confusion regarding LOD One of the versions of the interpretation of this abbreviation is Level Of Detail. The second version is the Level Of Development or the level of study. It's easier with LOI: I is usually understood here as Information, respectively, interpreting this term as a level of information processing – not the whole, but a non-graphical part of it.
Image 1 – LOD detail levels
But no matter how LOD is deciphered, we are talking about the requirements that determine the completeness of the detail and elaboration of each of the elements that make up the information model. In fact, in this way, the partners who will work with the BIM model agree on a certain amount of data that the model will contain: geometric, spatial, attributive, etc.
It is especially important that not only geometric data is written, but also alphanumeric. Among them:
- technical specifications,
- variants of execution,
- service option, etc.
It is so important to agree on common rules that some experts even introduce additional terms: Level Of Accuracy (LOA, also known as accuracy level), Level Of Geometry (LOG, geometry level). And in total, all this is called the Level Of Model Definition (LOD, the level of model development).
Depending on the stage at which the model will be used, different levels of detail are required. Somewhere minimal is enough, and somewhere all possible data is needed. Therefore, numbers are written next to the abbreviation – from 100 to 500. The larger the number, the higher the detail.
- LOD 100. This level of detail assumes only a general idea of the object, i.e. it actually represents a sketch. Based on the data contained, preliminary technical and economic calculations can be carried out.
- LOD 200. At this level of detail, the size and shape of the elements correspond to reality, but the degree of conditionality is still great. But still, this is a basic requirement for project documentation.
- LOD 300. In this case, the geometric shape and dimensions of all the elements included in the model, and their location and number are completely correct. At the same time, there is no accurate information about the manufacturer, suppliers, cost, etc. For the project documentation of stage A, the project documentation of the LOD 300 level is sufficient.
- The intermediate level is LOD 350. It is distinguished by the presence of accurate information about the connection of elements and their interaction with each other and other systems on the object.
- LOD 400 – it is relevant for Stage C project documentation. All elements are presented in the assembly taking into account their various parameters, dates of manufacture and installation, including information about the manufacturer.
- Maximum detail is achieved at LOD 500. In such a model, the actual location of the elements is indicated, and not the option provided for by the project. At the same time, the information is provided in full – this can include, for example, manufacturer's data, batch numbers, articles, information about the timing of installation or replacement, etc. This detail is especially useful when operating an object.
How to choose the correct LOD?
It is necessary to be guided by expediency and sufficiency. If we are talking about using an information model at the operational stage, then the LOD should be high. If the tasks are different, then the level of elaboration should not be too high. I.e., first of all, it is necessary to determine what a BIM model is needed for.