LOD, LOG, LOI, and LOIN: Terms that are widely used in the building industry. But what concepts do these terms represent?
To date, there are no definitions provided by regulations from authorities. Therefore, each company is free to establish its own definitions for these terms, leading to the emergence of several, sometimes slightly differing, definitions over time.
In collaboration, especially in complex projects, clear communication plays a crucial role for project success. While the introduction of LOIN (Level of Information Need) in 2021 aimed to replace the existing concept of LOD, it was indeed positive and helpful in this regard but for the Scan to BIM process, it hasn't been formulated comprehensively enough. This is why we have decided to create our own guideline for the "Scan to BIM" process and the existing model, focusing primarily on the various development stages from LOD100 to LOD400.
This document is intended to serve as a tool for orientation and communication among the client or planner, surveyor, and as-built modeler.
The terms LOG, LOI, and LOD are closely interconnected. At Miviso, we model buildings in 3D based on point clouds, thus primarily focusing on the geometric elements of a structure, referred to as the Level of Geometry (LOG). Depending on the requirements, we also incorporate alphanumeric material information (LOI) of a building. As most projects include alphanumeric data as well, our guideline addresses the Scan2BIM LOD Definition rather than LOG.
The distinctions between LOG, Level of Detail and Level of Development
As mentioned at the outset, there is no legal definition for these terms; nevertheless, some trends have emerged: Most commonly, in the "Scan-to-BIM" process, the term LOD is used and is then divided into four to five additional categories.
The origin of LOD lies in the term "Level of Detail." Over time, the term Level of Development has gained prominence, encompassing both geometric (LOG) and alphanumeric (LOI) information.
LOG + LOI is not equal to LOD
Simplified, it can be stated that the geometry and the information about the building together determine the Level of Development. However, LOD is defined on a project-by-project basis. This means that sometimes more geometric information (LOI200 + LOG300) is required, while other times more alphanumeric data (LOI300 + LOG200) is needed. Hence, LOG is independent of LOI.
LOIN: Level of Information Need
LOIN is an extended term derived from LOI, which is gaining increasing significance. The Level of Information Need pertains to the information content provided to the model by the owner or operator, addressing the project-specific requirement for information. This information encompasses both the planning and construction phases, as well as the operation and maintenance of the building. Only when the model is equipped with all data from LOIN (including both geometry-specific and information-specific data) can the individual BIM model be created.
The determination of LOIN involves at least three dimensions:
Geometric Information (LOG): individual components, representation, parametric behavior, dimensionality
Alphanumeric Information: Non-geometry-related, technical details, usage purpose, construction year, energy efficiency class
Other Informations and Dimension: Cost estimation, construction schedule, reports,…
What does Level of Geometry (LOG) mean for Miviso?
At Miviso, we are experts in 3D modeling of existing buildings. A 3D model is not automatically a BIM model according to LOD standards, but to create a BIM model, a 3D model adhering to a defined LOG standard—meaning geometry—is necessary as the foundation.
The precision with which we model geometry from point clouds depends on the Level of Geometry and the associated client requirements. Our tolerances typically range between 1 and 5 cm. Occasionally, we achieve tolerances below 1 cm, though it's important to note that this is feasible only for small spaces due to file size constraints and the need for highly accurate point clouds.
The LOG doesn't solely describe the maturity of geometry but, in our perspective, can also denote the tolerance of how much the geometry deviates from the actual building. The following illustration depicts the same component, a roof truss, from LOD100 to LOD400, effectively showcasing the differing levels of detail and the evolution of geometry.
How is the decision made regarding which LOD (LOG) to model during collaboration?
Typically, the client specifies the Level of Development in advance; however, we commence modeling only when we are certain that the client shares the same understanding of LOD/LOG as we do. To simplify this step in the future, we have developed the Scan2BIM LOD Definition.
Still uncertain about which LOD is suitable for your project? We are more than willing to take the time to advise you. "Having successfully executed numerous diverse projects, we have amassed a wealth of experience and are always eager to assist with our expertise."
Are there different LODs within a model?
When creating a building model according to a specific LOD, it's important to always consider the relevance of different levels of detail for individual spaces and components. Some of our case studies use descriptions like "LOD200 and LOD300," for instance.
This confirms that a level of detail doesn't necessarily apply uniformly to the entire model; it can also be determined individually for specific components. This is necessary because certain areas require higher or lower accuracy levels.
That's why we created the Scan2BIM LOD Definition.
The integration of geometry and information significantly influences the course of a project. At Miviso, we place great emphasis on ensuring that our clients and we are speaking the same language. Since a clear, legal definition of LOD is lacking, we have developed our own guideline, the Scan2BIM LOD Definition. The BIM approach is multifaceted, making a shared understanding of the concept fundamental to the successful execution of projects and forming the basis for a collaborative partnership on equal footing.
Please note that the Scan2BIM LOD definition currently exists only in German. The English version is still in progress and will be online soon.
Are you interested in the topic of 3D modeling (BIM) and want to learn more about it or do you have specific questions? We would be happy to have a conversation about it.
Michael Danklmaier
Miviso Co-Founder
Email: michael.danklmaier@miviso.com
Tel.: +43 664 4563309