by Chuck Eastman and Manu Venugopal
What is SEM?
A SEM is a structured, modular subset of the objects and relationships required in each one of multiple BIM exchange model definitions. It has two raisons d’être: ( 1) to enable BIM software companies to code import and export functions in modular fashion, such that a function written to export or import model objects according to any given SEM can be tested and certified once, and then re-used to fulfill multiple exchange model exports/imports without modification; (2) to provide a common high-level specification structure that allows non-programmers to compose an MVD at run-time by defining it in terms of SEMs, allowing multiple heterogeneous platform users to specify an SEM and to facilitate automatic compilation of the MVD on both sides to the exchange.
The central theme of this research is: “How can an improved model view development methodology be supported that reduces the inconsistency and redundancy of model views developed by parallel development teams, thereby improving the overall interoperability of BIM tools?”
There are two major research questions raised in this research and investigated as follows:
A. How can we develop model views consistently across research teams and domains?
In order to support IFC implementations, the consistency of model views designed is an important criteria. Lack of which causes an overhead to software developers and inhibits new IFC implementations.
B. What should be the building blocks of model views for semantic information exchanges?
The current approaches to model view development create redundant information that is spread across several domains due to lack of reusability. Defining the building blocks of model views and packaging them in an object-oriented, modular and reusable manner is needed.
A SEM Roadmap
A SEM can be defined as a binding to a set of IFC entities, attributes, relations, and functions and a corresponding set of Native model structures that carry the information associated with the IFC SEM definition. The SEM also carries the functions (methods) needed to reliably map data between the Native and IFC structures and other methods to integrate the two structures with associated SEMs. Once fully implemented, the SEM based approach can reduce the model view generation - implementation from the current 2 to 3 year period to that of three to six months. The SEM based approach has resulted in the static and domain specific model views to be converted into more dynamic and industry wide workflow specifications, thereby redefining the manner in which interoperability is addressed in the AEC/FM industry. A logical framework on the basis of well-defined and unit tested SEMs, thereby following a modular approach can be the future direction for creating exchange specifications and implementing them in a standardized and reusable manner, cutting across all domains and providing better interoperability.
National BIM Standard development projects currently supporting SEMs.
- Precast/Prestressed Concrete Institute (PCI) ►
- American Institute of Steel Construction (AISC) ►
- American Concrete Institute (ACI) ►