This article explains what Level of Information means in BIM-based projects. Also, it describes how the Level of Information (LoI) rule type works and how you can configure a rule based on the LoI rule type.
The purpose of this rule type is to determine the information content of the target components - i.e., to check whether individually defined attributes or properties are present and/or meet specified criteria.
The article covers the following topics:
- Level of Information and BIM
- Description of the Level of Information Rule Type
- Level of Information Rule Logic
- Level of Information Rule Requirements
- Level of Information Rule Check Results
Level of Information and BIM
In a BIM-based project, it is vital that building models contain the exact amount of information required for the use cases to be applied. For example: if you want to start with quantity take-off and cost calculation for your project, materials must be assigned to all building components.
Model information can be divided into geometric (description of the shape) and semantic (description of the meaning) information. The desired information content of a model is called Level of Development (LOD), and it describes the degree to which the information levels should be developed: LOD = LoG (Level of Geometry) + LoI (Level of Information). The LOD is usually formally recorded and can even be added as a part of the contractual documents (e.g. as a spreadsheet or as mvdXML).
Although there are some generic templates for how to set up the LOD for your project, the individual demands and use cases in a project require that there is a project-specific definition of the LODs. The specifications for the model are, therefore, project-specific and change over time. In addition to geometry, the availability, completeness, and integrity of the semantic information of the model play a vital role.
In the IFC schema, each element (component) has a precise definition and a list of precisely defined Attributes. The IFC schema also has Properties, which you can assign to components. Both attributes and properties can be checked to verify the correct level of information in the model.
Description of the Level of Information Rule Type
A Level of Information rule checks the depth of information in one or more target components. The LoI rule can check the information in both component attributes and properties. Here are some examples on how to use an LoI rule:
- Common practice: Ensure that all components have a Name that is not Empty.
- General specifications, e.g., according to BIM Basis ILS: Ensure that all wall components have a Property “LoadBearing” and “IsExternal” defined.
- Project-specific specifications: Ensure that all components that are relevant for QTO have a custom PropertySet “QTO”, and the Properties “Volume”, ”Area” and “Length”.
Level of Information Rule Logic
An LoI rule consists of one or many requirements regarding the information content a component can have. When the rule is applied, each target component found in the model is checked against these requirements. For each violation of a single requirement found, an error is documented.
Level of Information Rule Requirements
The IFC schema provides a clear framework of which IFC entity can have which information - information outside this framework cannot be mapped into IFC and therefore it makes no sense to specify requirements for this.
Therefore, the dialog is structured in such a way that at any time, depending on the IFC entity to be checked, only the information requirements which can actually exist for the component according to the IFC schema can be formulated.
You can configure the following requirements for an LoI rule:
- Targets: Select one or more target components that will be checked by the rule. Only targets with the selected IFC Schema can be selected.
- Drag and drop the item from the left to the space on the right. You can use the basic attributes, property sets and custom property sets you have created yourself.
The rule requirements depend on the selected target (more spefically, the target’s IFC Entity). Here's an example where the target is All Walls, and the IFC Entity is IfcWall.
Level of Information Rule Check Results
For each violation of a single requirement found, an error is documented.