The Model View Definition (MVD) is an essential basis for describing transfer requirements and their technical implementation. The implementation and certification of IFC in BIM applications is based on MVDs.
Benefits of MVD
An MVD is created in the context of a transfer requirement, e.g. the coordination of various specialist models. It defines a coordinated restriction (subset) of the IFC specification (IFC schema). This restriction focuses on the requirements (exchange requirements) of the creator and recipient of the information. The requirements are collected on the basis of an IDM (Information Delivery Manual) in accordance with ISO 29481. Limiting the IFC specification using an MVD can affect the following content:
- Element classes and types and
- QuantitiySets, Psetsandfeatures.
The integration of infrastructure requirements into the IFC specification results in an increase in the number of element classes required. It is becoming increasingly impossible to implement the entire IFC specification for BIM applications. The limitation of an MVD is a relief in this respect. It enables the functional scope of a BIM application to be tailored to the relevant requirements in the context of the MVD. The buildingSMART certification process for BIM applications is therefore based on MVDs. MVDs have a harmonizing or consolidating effect on the software market, as they represent a kind of template for the required range of functions in the creation, transfer and interpretation of information. MVDs are published by buildingSMART International.
Established MVDs and their objectives
Coordination View 2.0 (CV 2.0) is the first MVD to establish itself on the BIM application market. It was created in the context of IFC2x3 TC1 (2.3.0.1). The scope of CV 2.0 focuses on the provision of specialist models (architecture, structural design, building services engineering) for the overall coordination of building construction projects during the planning process.
The geometric transfer options are not overly restricted and allow for flexible adaptation. Model content can be transferred both with extruded geometry and with precise geometry (BREP – Boundary Representation). The transfer with extruded geometry allows the best possible native reuse in the target application. In contrast, transfer with precise geometry (BREP) enables exact geometry reproduction in the target application. In BREP mode, components can be broken down into their constituent parts (e.g. wall layers) and output as individual parts (components). In this way, it is possible to evaluate/analyze a model layer by layer. A complex geometry is transferred triangulated in IFC2x3.
CV 2.0 has been certified for many BIM applications on the market and is currently the most widely used MVD. Due to a lack of alternatives, it is sometimes also used on an interim basis for transport infrastructure projects, in which IfcBuildingElementProxy is still being improvised intensively due to infrastructure element classes that are not yet available or implemented in advance in the BIM application. The mere alignment of the location (SpatialStructure) to the building construction or the imprecise handling of the coordinate system of the BIM applications (in interaction with IFC) often poses a problem.
Reference View 1.2 (RV 1.2) is the second established MVD. It was created in the context of IFC4 ADD2 TC1 (4.0.2.1). The scope of RV 1.2 focuses on the provision of specialist models as a reference (architecture, structural design, building services engineering) for the overall coordination of building construction projects during the planning process.
The geometric transfer options are limited (in contrast to CV 2.0) and are geared towards the use case of model coordination. Model contents are transferred with precise geometry (BREP – BoundaryRepresentation). This enables exact geometry reproduction in the target application. In BREP mode, components can be broken down into their constituent parts (e.g. wall layers) and output as individual parts (components). In this way, it is possible to evaluate/analyze a model layer by layer. IFC4 ADD2 TC1 (4.0.2.1) now also offers the geometry description for BREP using NURBS. This is much more precise and space-saving (data volume) than the triangulation methods in IFC2x3.
RV 1.2 has now been certified for a large number of BIM applications on the market. RV 1.2 is also sometimes used for transportation infrastructure projects due to a lack of alternatives. The pure orientation of the location (SpatialStructure) to building construction often poses a problem. The certification of RV 1.2 is less tolerant of errors, which is why the implementation of RV 1.2 certifications takes more time than for CV 2.0. However, it can also be assumed that the implementation quality of BIM applications is significantly more homogeneous.
Future MVD and its objectives
As RV 1.2 implements the use case of model coordination in a much more focused way than CV 2.0, at least a second MVD is required for IFC4 that supports the use case of model transfer(interoperability). This is necessary, for example, for the provision of the architectural model to the structural engineer so that he can build his structural model. This is also necessary for the model transfer to the client at the end of the project so that the client can subsequently update changes to the structure in the model.
The Design Transfer View 1.1 (DTV 1.1) was developed for this purpose. It was created in the context of IFC4 ADD2 TC1 (4.0.2.1). The scope of DTV 1.1 focuses on the transfer of technical models between two BIM applications – but only in one direction and not in a round trip. The geometric transfer options are limited (in contrast to CV 2.0) and focused on the use case of model transfer. Model contents are transferred with extruded geometry and a limitation of their functionalities. This enables native reuse in the target application. DTV 1.1 is not yet certified for BIM applications (as of 01/2024).
Quantity Takeoff View 0.1 (QV 0.1) is an MVD that is aimed at the use case of model-based mass and cost determination. This is currently under development(status draft) and is not yet certified for BIM applications (as of 01/2024).
The Basic FM Handover View (FM) is an MVD that is aimed at the use case of transferring model information to FM (facility management) at the end of the project. It was created in the context of IFC2x3 TC1 (2.3.0.1). FM has official status, but is not yet established on the market and is not yet certified for BIM applications (as of 01/2024).
Product Library View 0.1 (LV 0.1) is an MVD that is aimed at the use case of transferring digital product information(DataTemplates). This is currently under development(StatusDraft) and is not yet certified for BIM applications (as of 01/2024).
Other MVDs under development can be found on the buildingSMART International website(link).
Publication from Eichler, C.C., Schranz, Ch., Krischmann, T., Urban, H., Hopferwieser, M., Fischer, S.: BIMcertHandbuch- Grundlagenwissen openBIM. Issue 2024. Mironde-Verlag, Niederfrohna, 2024. DOI: 10.34726/5384
URL: https://repositum.tuwien.at/bitstream/20.500.12708/192612/3/Eichler-2024-BIMcert %20Handbuch%20basic-knowledge%20openBIM-vor.pdf
Status: 23.01.2024