What is LOD and How Does It Affect 3D Modelling?
- PV Digital
- Apr 24
- 7 min read
By employing LOD as a reference framework, professionals in the Architecture, Engineering, and Construction (AEC) sector may produce reliable and understandable BIM workflows and models across a range of project life cycles.
The page discusses the six phases of development, which are LOD 100 through LOD 500. The geometric and informative detail of the model components increases steadily with each level. Additionally, we will examine the many stages of 3D modeling development.
What is LOD?
Professionals in the AEC Industry can create dependable and intelligible Building Information Models (BIMs) at various stages of their project life cycles by using the "Level of Development (LOD) Specification" as a guide.
The depiction of geometric information in an element of a 3D model is commonly referred to as Level of Detail (LOD). The LOD definition enables industry experts to precisely describe how the geometry and related data of an element have changed over time. It represents the extent to which various team members can depend on knowledge related to an element.
There are six levels of development, namely, LOD 100, LOD 200, LOD 300, LOD 350, LOD 400, LOD 500. In this case, LOD 100 indicates that the model contains less geometric information than LOD 200.
Concept and History of LOD
Marzia Bolpagni's paper "Many Faces of LOD" (MACE) provides a useful summary of the development and history of LOD. According to that article, the first time LOD was utilized was in 2004 by Vico Software, a construction analysis software company that is now a part of Trimble.
They employed a technique similar to LOD to link digital models to project costs.
Later, in 2008, the American Institute of Architects (AIA) coined the term LOD. In the Building Information Modeling Protocol Exhibit, it added five "Levels of Development" (LOD 100–LOD 500), which were later revised in 2013.
In a number of nations, including Australia, Canada, Singapore, China, Taiwan, Germany, and France, these documents became the standard. Other nations created their own specifications for their variants.
The Need for Standardising the “Level of D”
Standardizing the "Level of D" was necessary to prevent misunderstandings because this procedure was quite comparable across nations and building projects. Concepts like "level of detail," "model progression specification," and "level of development" were created for this purpose.
The "Level of Development Specification," which is based on guidelines from the American Institute of Architects (AIA) and is published and updated annually by BIMForum, is one popular specification for LOD.
Here are some of the most important concepts from the BIMForum specification:
Since several objects may be at varying stages of development inside a same model, the level of development is expressed at the object level rather than the model level.
Instead of using "detail," the word "development" is used to convey the level of reliability of the material, not its level of detail.
Although intermediate levels could theoretically be added if necessary, five primary levels have been initially specified using a numerical designation in steps of 100. Although the names themselves are relatively arbitrary, they do capture the slow evolution that usually occurs in a project.
The U.S. Army Corps of Engineers (USACE), BIMForum, and AIA are the three main LOD matrices currently in use in the US. Although each takes a somewhat different approach, they are all predicated on the same idea.
Benefits of LOD
Implementing BIM without establishing LODs or designating the appropriate staff to use the tools frequently results in needless field adjustments. Using Levels of Development in a BIM model has several advantages. Let's investigate a few of these:
It makes it easier for all project participants to collaborate so that there are no discrepancies that could jeopardize the project's chances.
Collaboration and communication are facilitated and accelerated when all parties involved are in agreement.
Designers can give instructions and data to those working downstream to guarantee flawless execution and maintenance with the aid of defined standards and comprehensive information about every component.
Design managers may more easily and effectively communicate to teams the needs from a 3D model at different stages of the design process thanks to LOD.
Additionally, LOD facilitates the establishment of a standard for contractors responsible for BIM execution.
Why adopt LOD for BIM Model?
Using Level of Development (LOD) in BIM modeling ensures accuracy, consistency, and clarity across project phases. By using it to specify the dependability of model parts, teams may better understand the amount of information and detail accessible at each level. Standardization improves decision-making, collaboration, and error-prevention, which ultimately leads to cost savings and successful project completion.
Difference Between Level of Detail and Level of Development
Aspect | Level of Detail | Level of Development |
Definition | The amount of graphical and non-graphical information associated with each element of the building information model. | The comprehensiveness of information attached to the BIM elements outlines the reliability of the data and how much can be expected from the model at various stages of the project. |
Focus | Primarily emphasises the visual accuracy and complexity of the model, detailing the graphical representation of elements. | Encompasses both the graphical representation and the depth of information attached to each object, such as structural or material data. |
Purpose | Helps communicate the appearance and shape of model elements, aiding in visualisation and design intent. | Provides a comprehensive understanding of the model’s development status, ensuring all stakeholders have accurate and reliable information. |
Application | Commonly used in the design and visualisation stages to convey the aesthetic and spatial aspects of the project. | Applied throughout the project lifecycle, from design to construction and operation, ensuring that each element is developed to the appropriate level for its intended use. |
Measurement Scale | Typically measured on a scale from LOD 100 (conceptual) to LOD 500 (as-built), indicating the progression from basic massing models to detailed representations. | Similarly measured on a scale from LOD 100 to LOD 500 but with a focus on the reliability and completeness of both graphical and non-graphical information. |
Level of Development vs Level of Detail
There is often a confusion between the two terms - Level of Development and Level of Detail. Let us understand the definitions of both to understand their differences.
1. Level of Development
The level of development of a BIM model refers to the amount of information which is relevant to the concrete development of the project. It 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.
2. Level of Detail
The level of detail designates the entire amount of information that the BIM element contains. It is essentially how much detail is included in the model element. If all this information is relevant to the setting-up of the construction project, the two concepts overlap.
3. Difference between Level of Detail and Level of Development
In short, "Level of Detail" relates to an object's graphical representation, whereas "Level of Development" refers to both the object's information (properties) and its graphical representation.
The quantity of information supplied to the model element is measured by the Level of Detail. Because it is merely a measure of quantity, the underlying assumption is that all presented information is relevant to the project and hence can be relied upon with certainty.
The degree to which the geometry and associated data of the element have been carefully considered is known as its Level of Development. Essentially, Level of Development is the element's dependable output, whereas Level of Detail can be regarded of as its input.
Various Levels of Development in BIM
There are six levels of development, namely, LOD 100, LOD 200, LOD 300, LOD 350, LOD 400, LOD 500.
1. LOD 100 - Conceptual Design
The complete building massing would be included in the model at LOD 100, and downstream users would be permitted to conduct analyses of the entire building (volume, building orientation, cost per square foot, etc.).
2. LOD 200 - Schematic Design
"Generalized systems or assemblies with approximate quantities, size, shape, location, and orientation" would make up this model. "Analysis of selected systems by application of generalized performance criteria" is one of the authorized uses.
3. LOD 300 - Design Development
In terms of amount, size, shape, placement, and orientation, the Model Element is graphically depicted as a particular system, object, or assembly within the Model. The Model Element may also have non-graphic data associated to it.
4. LOD 350 - Construction Documentation
It contains written definitions, visuals, and model details that illustrate how different building pieces interact with one another and with other systems.
5. LOD 400 - Fabrication and Assembly
In addition to exact amount, size, shape, placement, and orientation, model elements are modeled as individual assemblies, replete with manufacturing, assembly, and detailing information. It is also possible to attach non-geometric data about the model's components.
6. LOD 500 - As-Built
For operations and maintenance, elements are modeled as built assemblies. Non-geometric information is added to modelled elements along with precise and real size, shape, location, amount, and orientation.
Let's examine the structural kicker detailing procedure to gain a better understanding of this. This example is from the second edition of the book "BIM and Construction Management."
A structural engineer could draw the beams and kickers at LOD 100 in plan view and additional LOD 100 detail in elevation.
The structural engineer could employ a hybrid strategy in which he models the beams at LOD 200 or 300 while annotating the kicker locations in plan view and the LO D 100 information in elevation using LOD 100.
Both the beams and the kickers may be modeled by the structural engineer, who would then position the kickers at a general angle (LOD 200) but at the proper location.
The structural engineer might use BIM's parametric features to automatically create an elevation view equivalent by modeling the beams and kickers at LOD 300 (or higher).
Conclusion
To sum up, experts in the domains of engineering, architecture, and building need to understand and apply the Level of Development framework.
By adhering to established LOD standards, project teams may ensure consistency, improve stakeholder communication, and facilitate efficient project execution and maintenance.
The structured method of LOD not only makes the evolution of model elements easier to grasp, but it also increases the overall dependability and effectiveness of BIM installations.
Stay tuned with PrimaVerse as we share current insights and trends in the engineering industry, including the latest in generative design. Have a project in mind? Contact us today and let’s build a better world together!
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