Explaining the Difference Between Level of Detail and Level of Development in BIM Modeling

In the architecture, engineering, and construction (AEC) industry, confusion often arises between the terms Level of Detail (LOD) and Level of Development (LOD). Although both acronyms describe aspects of 3D Building Information Models (BIM), they are not interchangeable and have distinct meanings.

While both concepts refer to the information and detail within a BIM model, Level of Detail focuses primarily on the visual and graphical representation of an object. In contrast, Level of Development includes the graphical representation and further includes the depth of information attached to that object, such as structural or material data.

Understanding the differences and proper usage of LOD is essential for architects, virtual design consultants, and CAD professionals to communicate effectively, ensuring projects are scoped accurately and executed efficiently.

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There is a defined set of LOD specifications for both level of detail and level of development that help AEC professionals document, articulate, and specify 3D BIM models effectively.

Level of Detail vs. Level of Development

The difference between Level of Detail and Level of Development becomes clear in the context of 3D modeling, especially when working with laser scan data. Level of Detail emphasizes the visual accuracy and complexity of the model, while Level of Development goes further by defining how much information is attached to the model elements and how reliable that information is.

RELATED: Scope of Work & LOD

What is Level of Detail (LOD)?

Level of Detail refers to the graphical representation and non-graphical information of each element in the BIM model. The level of accuracy and detail in the visual depiction increases as the model progresses through different stages, categorized as LOD 100, 200, 300, 400, and 500. Higher levels indicate more precise and detailed representations.

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BIM Levels of Detail Explained

• LOD 100: This represents the basic massing or volume of objects. It’s a rough, conceptual depiction used for early-stage feasibility studies or initial design concepts.
• LOD 200: Elements are more defined but still generic, with approximate shapes and sizes. It's useful during schematic design phases where precise material or system specifications are not yet required.
• LOD 300: This level introduces more accurate shapes, positions, and dimensions. LOD 300 models provide enough detail for construction documents and project coordination.
• LOD 400: Detailed enough for fabrication, these models accurately represent not only the geometric aspects of objects but also the layers and materials of walls, ceilings, and other elements.
• LOD 500: This level provides an as-built model, capturing all dimensions and properties as verified in the field. It's often used for facility management and future maintenance planning.

What is Level of Development (LOD)?

Level of Development describes the comprehensiveness of information attached to the BIM elements. It outlines the reliability of the data and how much can be expected from the model at various stages of the project. Like the Level of Detail, Level of Development progresses from conceptual stages to highly detailed, as-built models, following LOD 100, 200, 300, 350, 400, and 500 specifications, as defined by the American Institute of Architects (AIA), and developed in part by the BIMForum working group.

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BIM Levels of Development Explained

• LOD 100 – Conceptual Design: Represents elements conceptually, using generic shapes with approximate geometry to provide an overall understanding of the spatial environment and design.
• LOD 200 – Schematic Design: Elements are modeled with rough dimensions and specifications as a generic system, object, or assembly, suitable for schematic designs, but always to be considered approximate only.
• LOD 300 – Design Development: This provides a precise depiction, including sizes, shapes, orientations, and installation data, used for construction and design planning.
• LOD 350 – Construction Documentation: 350 is similar to LOD 300, but also includes connections and interfaces with other building systems, making it useful for construction coordination.
• LOD 400 – Fabrication & Assembly: Models at this level are fabrication-ready, with highly detailed geometry and information about the materials, sizes, orientation, and installation data. This level includes everything you’d find in a 300-level model, plus the specifics on the manufacturer, costs, etc.
• LOD 500 – As-Built Model: Field-verified as-built models reflect the exact specifications and locations of all elements within the building. It is considered a close replica of the existing building and contains 100% of the information required for effective decision-making, so it is valuable to management through the building life cycle and operations and maintenance (O&M).

LOD and 3D Laser Scanning

Though Level of Detail and Level of Development weren’t initially designed with 3D laser scanning in mind, they provide a useful framework for organizing the data captured by LiDAR technology. Laser scanning creates a point cloud from which a BIM model is generated, and specifying the appropriate LOD ensures that project teams know the level of accuracy and detail required.

When developing a project proposal, it’s crucial to define the LOD expectations. The higher the LOD, the more detailed and reliable the model, allowing for better collaboration among architects, engineers, and other professionals.

For exacting LOD on your next as-builts, BIM model, or CAD deliverable development, call Existing Conditions. We're here to help you optimize your BIM projects and ensure every element is modeled to the precise specifications you need.

When you need to Start Accurate and Stay Accurate™, contact Existing Conditions today!

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