Technical University of Munich
Munich, Germany
An approach to enrich and validate IFC models by translating given data into EIR
The project aimed to improve the semantic quality of a BIM model by preparing it for automatised downstream processes such as model-based QTO or model-based Energy Analyses. Therefore, the project proposes a novel approach to enrich IFC models by mapping provided information with internally standardised Exchange Information Requirements (EIR).
This approach covers several aspects:
- A data model (IMIR) that stores EIR and allows for mvdXML export
- Mapping semantic information from an IFC model with the IMIR
- Model validation and export of BCF issues referencing the missing information
Eventually, the project introduces a prototype covering the features.
This approach brings value to openBIM. It shows how to integrate bs standards into a coherent workflow. The solution can
- define information requirements using mvdXML
- validate IFC models
- export BCF issues automatised
BIM models comprise extensive data that the project team can use to automatise BIM Uses based on algorithms. However, such an algorithm queries and analyses information regarding their labelling. As various stakeholders may label the same information differently, project participants need to update their algorithms for every data exchange manually. What one may name ‘compressive strength’, one may call ‘resistance class’ and another may label ‘concrete class’. Thus, a contractor receives a model and wants to execute automatized cost estimation. Their algorithm refers to elements with a ‘resistance class’ of ‘C30/37’. However, the model author labelled it differently. For that reason, the contractor must edit the algorithm. What may seem as a little issue becomes significant considering that there are thousands of properties in a model. These adjustments especially result in a high workload when applying multiple BIM Uses on one BIM model. Even though the buildingSMART datqa dictionary tackles this issue, the problem is present in construction industry. The bsdd lacks completeness and therefore lacks acceptance.
This research project presents a novel approach to enrich BIM models, in the form of IFC, by translating provided information into internally standardised information requirements that base on Exchange Information Requirements (EIR), but extend them by another dimension: the labelling requirements. The author proposes the model of Internal Model Information Requirements (IMIR) to store and maintain both dimensions. Additionally, it introduces hierarchically structured information requirements. The hierarchy is essential as different data triggers different requirements. For example, the material Concrete requires different information than the material Timber. The IMIR-model eventually allows for mvdXML export.
Afterwards, the IMIR-model functions to assign data from an IFC model to data from the IMIR itself. The Enrich-IFC-model stores these assigned pairs and derives an enriched IFC model containing both, the original information and the internally standardised information. Moreover, the Enrich-IFC-model allows for model validation and export of model-related errors for collaboration in the form of BCF files. The exported BCF files support the communication with the model creator. Therefore, the files contain information about the missing attributes and components. Moreover, they colour the components according to the test result. For example, instances defining a material are stored with green colour. Instances that fail the requirement are displayed in red while components that do not require this information are not attached.
The author converts the approach into a prototype that provides core functionalities of the Enrich-IFC-model, including a graphical user interface. The thesis compares the innovative approach with a conventional approach applying them to the BIM Use Cost Estimation to prove the value. The Enrich-IFC approach does not yet decrease the workload. However, developing the usability of the prototype and applying it to multiple BIM Uses is expected to minimise manual work intensively. Compared to the conventional approach, the main benefits of the novel Enrich-IFC-approach are:
- Coherent and flexible structure of information requirements
- Comprehensible model validation supporting BCF communication
- The expert only needs to work with one application instead of multiple as downstream processes work automatised
The project shows how to integrate the three standards IFC, mvdXML, and BCF into an open-based software tool. This tool helps a stakeholder to maintain their information requirements, validate models and prepare BIM models for fully-automatised BIM Uses. This is where the proposed solution innovates. A stakeholder can fully automatise downstream processes such as Cost Estimation. They prepare the Cost Estimation and only use the information from their internal EIR. Instead of changing all algorithms in the Cost Estimation, the stakeholder can translate the given information according to their requirements. After that, the IFC model complies with the EIR. Thus, the stakeholder imports the model into the Cost Estimation algorithm that now can interpret all data and execute the Cost Estimation automatised.
Software vendors handle the BCF standard differently. The standard shall define optional and mandatory fields more clearly.
