Harmonization of the IFC View Definition Methodology BLIS - ProIT - IDM

1. Harmonization of theIFC View Definition MethodologyBLIS - ProIT - IDM Jiri Hietanen BLIS Technical Coordinator 30.05.2005 - VIRTUAL BUILDING LABORATORY

2. The Harmonization Team • Team • Jiri Hietanen, BLIS • Kari Karstila, ProIT • Jeff Wix, IDM • Efforts to date • Finding common approach (by email) • Finding technical solutions (half day workshop in Helsinki) • Generating content examples from BLIS and IDM - VIRTUAL BUILDING LABORATORY

3. Content Content Content Content Examples Harmonization of the methodology BLIS IDM ProIT Format Format Format Examples Examples IAI Format - VIRTUAL BUILDING LABORATORY

4. The Proposal(which was accepted by ITM in Madrid) • Clearly separate the format and content of an IFC view definition • IAI agrees on and publishes the official format for IFC view definitions • Creating IFC view definitions (content) is open to any organization/group • The IAI has the option to contract the development of view definitions • IAI endorses certification for IFC view definitions it considers to be valuable. These view definitions must follow the official format. • The IAI organize certification itself or can appoint, contract, or endorse an organization to administer official IFC view based certification of applications. • The cost of certification could be paid by the IAI or by the vendors seeking certification. • Only view definitions, for which there is an IAI endorsed certification, become official IFC view definitions • This will not delay any ongoing view definition or certification activities - VIRTUAL BUILDING LABORATORY

5. Managing all this it too much for any single organization/group! The Goal(as presented in Madrid) • “The Predictable Interoperability Experience” • Not perfect, but crystal clear • Reached through the combination of view definitions and certification …so the work has to be divided in a way that doesn’t lead to anarchy - VIRTUAL BUILDING LABORATORY

6. The Goal • The goal is to create a framework or methodology, which defines the requirements, methods and format for IFC view definitions, such that view definitions created by different parties are consistently defined and documented, and comparable. • Final deliverable will be “IAI Methodology for IFC View Definitions” - VIRTUAL BUILDING LABORATORY

7. General Considerations • The scope of the IFC Object Model is larger than that of any end-user application. • There is a need to define true, unambiguous subsets of the IFC Object Model, which are used in specific data exchange in support of a business scenario. • IFC view definitions are needed for making IFC based data exchange reliable and predictable. Users must know when and how IFC based data exchange can be successfully used in AEC/FM projects. • Because of this requirement, IFC View definitions must take into account the capabilities and limitations of currently available software. - VIRTUAL BUILDING LABORATORY

8. Audiences for IFC View Definitions • End users of software; information about the possibilities of IFC based exchange • Software developers; IFC interface implementation specification • Organizers of software certification; certification is done against view definitions - VIRTUAL BUILDING LABORATORY

9. How to get IFC view definitions accepted by the industry? • For software developers, identify the IFC capabilities required (both entities and property objects), attributes that must be set to achieve the objective of the view and document agreements made between software developers. Following view definitions should be the easiest way to implement IFC support in software. • For organizers or software certification, provide a clear and unambiguous technical documentation of the view definition, which can be easily used in the development of certification procedures and test cases. • For the user, provide a simple to understand plain language description of IFC view definitions, which address real and important industry data exchange cases. Certification should provide additional information specific to the capabilities and limitations of the individual certified software products. • In general, find a useful balance between the wishes of users and the possibilities of software developers, and document the outcome clearly. • Expectations should be set from the outset to usefulness, not perfection. - VIRTUAL BUILDING LABORATORY

10. Requirements for IFC view definitions1/2 • Relevance (and scope): View definitions should address real, important industry data exchange use cases • Unambiguous specification: a View definition should provide an unambiguous specification on how IFC is used to support a specific data exchange use case. I.e. View definition should not leave space for multiple interpretations. Implementer’s agreements are part of the view definition. • Follow IFC Object model and its principles: The solutions taken in the View definitions should be in coherence with the IFC Object model and its underlying principles. (Note: I.e. one should not take quick an dirty short cut agreements in View definitions, if there is a better way to do it with the IFC Object model). • Cross View definition consistency: Different View definitions should use the same representations structures to address the same exchange requirement. - VIRTUAL BUILDING LABORATORY

11. Requirements for IFC view definitions 2/2 • Multirelease support: The View definitions should take into consideration the evolving, multi-release nature of the IFC specification. • Re-use: The documentation structure of the View definitions should support the re-use of definitions, concepts, representations structures, documentation parts, ... • Implementability: The View definitions should not be unnecessary complex to implement. • Understandability: The View definitions should provide an easily understandable and useful description of the purpose and the scope of the View definition for the identified audiences. (Note: Different audiences need a different kind of documentation). • Software tools: It must be possible to create and document view definition content using readily available software. Standard diagrams should be used whenever possible. - VIRTUAL BUILDING LABORATORY

12. IFC View Definition Structure - VIRTUAL BUILDING LABORATORY

13. High Level Description • Audiences • End users of software • Organizers of software certification • Software developers (decisions) • Format • Textual description with diagrams • Requires template (MS Word) • Delivery as PDF - VIRTUAL BUILDING LABORATORY

14. High Level Description of an IFC View(example from BLIS – 1/2) Arch. design >> Indoor Condition Analysis / HVAC system design The view for 'Arch. design >> Indoor Condition Analysis / HVAC system design‘ defines the subset of the IFC model used for transferring data from architectural design applications to HVAC system design applications through indoor condition analysis (optional). The most important part of the model for this view are building geometry (walls, doors, windows, slabs) and spaces. The exchange of building element data relies on construction types, which are agreed upon separately in each building project. Thermal properties of building elements (U-values etc.) are not exchanged. Indoor condition analysis applications calculate space instance specific requirement values for HVAC systems, such as  the maximum required air flow rate for a space instance. This requirement data is written back to the IFC data as property sets attached to space objects. HVAC system design applications import the building geometry and spaces from the architectural design application and the requirement data generated by the indoor condition analysis (optional). The requirement data use typically used for dimensioning the HVAC systems. HVAC components are not exchanged in this view. - VIRTUAL BUILDING LABORATORY

15. High Level Description of an IFC View(example from BLIS – 2/2) Quantity Take-off Document - VIRTUAL BUILDING LABORATORY

16. IFC Independent Concepts • Audiences • End users of software • Organizers of software certification • Software developers (decisions) • Format • Textual description with standard diagrams • Requires templates (MS Word, MS Visio) • Delivery as PDF - VIRTUAL BUILDING LABORATORY

17. Constant and variable concepts • Some concepts are simple some more complex • Aggregation, opening elements, construction type, space… • Problem: Views consist of concepts, but some concepts have views • Proposed Solution • Walls, doors, windows, spaces etc. called ‘variable concepts’ (high level parts). Primarily dealing with subtypes of IfcObject. • Properties, classification etc. called ‘constants concepts’, ‘view independent concepts’ (low level parts). This includes the things we need to connect a-to-a or a-to-b, which are also ‘constant concepts’. Primarily dealing with resources and relationships. • The view definition first makes a selection of the ‘variable concepts’ used by that view. As a second step the view definition configures the selected variable concepts. • Example: How is the ‘variable concept’ of space is used in the view arch. design  quantity take-off Example - VIRTUAL BUILDING LABORATORY

18. IFC Binding of a View Definition • Audiences • Software developers (coding) • Organizers of software certification • Format • Textual description with standard diagram • Requires templates (MS Word, MS Visio) • Delivery as PDF Example - VIRTUAL BUILDING LABORATORY

19. IFC Binding of a Concept • Audiences • Software developers (coding) • Organizers of software certification • Format • Textual description with standard diagram (for variable concepts) • Requires templates (MS Word, MS Visio) • EXPRESS-G Diagram • Considering ifcUML and optional EXPRESS sub-schema • Instantiation diagram(s) • Requires templates (MS Visio) – format not decided • Additional Documents • Delivery as PDF Example Example Example - VIRTUAL BUILDING LABORATORY

20. Extending IFC View Definitions • Levels • Some things can be defined on a global level • Others need to be defined on a national / enterprise / project level • IAI International and international implementers work on the global level, but have to make the national / enterprise / project level possible. • Jeff has some documentation for this • Official IAI View Definitions are global • ProIT, IDM and Japanese PropertySets are examples of national efforts • Need to find balance between global and national / enterprise / project levels - VIRTUAL BUILDING LABORATORY

21. How does an IFC View become official? • Creation of a IFC View Definition • Endorsement by the IAI as ‘candidate for certification’ • Certification, in which the view becomes ‘official’. • The candidate may be modified until it becomes official. - VIRTUAL BUILDING LABORATORY

22. Remaining Tasks • Ratification of the proposed methodology • How does the format become the official “IAI Methodology for IFC View Definitions”? • Creation of templates • MS Word / MS Visio • New “IFC View Definition Review Board”? • IVDRB  • Promoting the development of IFC View Definition content • (Using the view definition methodology for IFC extension projects) - VIRTUAL BUILDING LABORATORY

23. Thank You Technical issues are easy, reaching agreement is difficult and takes time. - VIRTUAL BUILDING LABORATORY