Architectural BIM modeling: Comparison of different LODs

Architectural BIM modeling: Comparison of different LODs

Level of Details (LOD) is a factor that determines what kind of data is required to be put in a model. It is one of the most important components of  BIM technology. LOD standards were developed by VICO software, a company that produces construction costing software. It enables professionals in the architectural, engineering and construction (AEC)  industry  to distinguish and articulate with a high level of lucidity, the content and dependability of Building Information Models (BIMs) at assorted levels in the design and construction process. LODs depict and define the elements that a particular model can be relied on for, and allows users to clearly comprehend the usability and confines of the models that are relied on. It identifies how the 3D geometry of the building model can achieve various levels of refinement. This is also used as a measure of the service level required.  The  objective of this component is to assist elucidation of the levels of detailing or development framework and homogenize its use, so that it turns into a more constructive communication tool. This specification does not negate the requirement of a project BIM execution plan (BIMXP), rather it is intended to be used in conjunction with such a plan.

DIFFERENT LEVELS OF DETAILING

  • LOD 100 ( concept design) : the element in the model with LOD 100, can be graphically represented using a symbol or a more generic representation. Information associated with the model element like cost, will need to be resultant from other model elements.  Only conceptual models can be created with this level of detailing.
  • LOD 200 ( schematic design): the element in the model with level 200, is represented graphically, as a generic system, assembly or object, with approximate quantity information regarding the size, dimension, orientation etc.  Non-graphic  or non- geometric information might also be added to the model element.
  • LOD 300 ( detailed design) : in this level of detailing, accurate modeling and shop drawings are made with specific information regarding the assemblies, quantity, shape, location and orientation. Here we can add non-geometrical or non-graphic information can be used too.
  • LOD 350 ( construction documentation): the model element is represented graphically either as a specific system, or as an assembly in terms of shape, size, quantity orientation and other building system orientations. It depicts how building elements interface coordinate with various systems and other building elements.
  • LOD 400 ( fabrication and assembly ): like the name suggests, this level of detailing deliver complete fabrication and assembly, providing detailing information in addition to the shape, size, quantity, location, orientation. Non- geometric information can also be attached.
  • LOD 500 ( as-built) : modeled like constructed assemblies the model elements, requiring this level of detailed information is a field-verified representation of shape, size, quantity, orientation etc.  Non- graphic or non- geometric  information might also be attached.

Therefore, as the levels of detailing, goes up, more and more information is stacked on to the model element.

There is no such clear characteristic distinction between level of development and level of detailing, because no amount of development is possible without the right amount of detailing. There have been confusions between level of detailing and level of development, so most BIM planners and guides use other terminologies for LODs :

  • CIC (Penn state)
    “Information Level of Detail” – AKA “Info”
    A – Accurate size & location, including material and object parameters
    B – General size & location, including parameter data
    C – Schematic size & location
  • USACE M3
    “Grade”
    A – 3D + facility data
    B – 2D + facility data
    C – 2D, part of an assembly or text description
  • AEC (UK) BIM Protocol
    “Graded Component Creation”
    G0 – Schematic
    G1 – Concept
    G2 – Defined
    G3 – Rendered

An LOD model is an imperative record of approved tasks around a BIM model.  It only relates to the BIM model and not other deliverables or responsibilities. For every part of the BIM model and different stages of detailing, it is important to know the following :

  • the author and the responsible party.
  • things declared and not declared in the BIM model.
  • to what degree the information entrenched can be used with certainty.

Thus, in the industry, LODs render more clarity in the BIM model concerning the project that is to be taken  and the everyday strategies on how to ensue  it. LODs also help in distinguishing and specifying responsibilities of a number of people in charge for an assortment of works needed to be done .And thus, it helps professionals to have a premeditated approach to a project, thus reducing time during the construction , eventually reducing costs and maximizing profit margins.

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