Curating Architectural 3D CAD Models

Increasing demand to manage and preserve 3-dimensional models for a variety of physical phenomena (e.g., building and engineering designs, computer games, or scientific visualizations) is creating new challenges for digital archives. Preserving 3D models requires identifying technical formats for the models that can be maintained over time, and the available formats offer different advantages and disadvantages depending on the intended future uses of the models. Additionally, the metadata required to manage 3D models is not yet standardized, and getting intellectual proposal rights for digital models is uncharted territory. The FACADE Project at MIT is investigating these challenges in the architecture, engineering and construction (AEC) industry and has developed recommendations and systems to support digital archives in dealing with digital 3D models and related data. These results can also be generalized to other domains doing 3D modeling. The International Journal of Digital Curation is an international journal committed to scholarly excellence and dedicated to the advancement of digital curation across a wide range of sectors. ISSN: 1746-8256 The IJDC is published by UKOLN at the University of Bath and is a publication of the Digital Curation Centre. Curating Architectural 3D CAD Models 99 Computer-Aided Design in Architecture Use of 3-dimensional Computer-Aided Design (3D CAD) software is routine in most design professions, including architecture, engineering, archeology, conservation, and other disciplines that deal with the built world – past, present, or future. 3D modeling is also routinely used in science, technology and medicine to describe and visualize physical phenomena. 3D is increasingly used in interactive teaching tools and virtual environments like Second Life. 3D models describe the geometry and other attributes of physical objects, and are dynamically visualized with computer graphics. Compared with most other digital data formats, 3D models are very complex and the formats used to store them are typically proprietary to a particular software product, presenting further challenges to long-term curation. Despite the prevalence of 3D models among the data that digital archives are ingesting and the many challenges they present for long-term curation and preservation, very little research has been done on curating them. In the field of architecture, 3D CAD software is becoming the design tool of choice. There are many software vendors supplying the architecture, engineering and construction (AEC) industry, most notably AutoCAD and Revit from Autodesk, CATIA from Dassault Systèmes, and Bentley’s Microstation and GenerativeComponents. 3D models are increasingly employed across all phases of building projects, and are beginning to be seen as useful for ongoing product lifecycle management (e.g., for ongoing building or aircraft maintenance). The workflows that use 3D CAD in building projects are currently ad hoc and prone to translation errors between the varying products deployed by different parties involved in a project. This has led the AEC industry to define a “Building Information Model” as a standard way to model buildings in 3D. BIMs include the 3D CAD model plus significant properties of the model (e.g., features and materials) to facilitate communication between the different parties involved in the project and the future building owners. A few CAD modeling products claim support for BIM (e.g., Revit, GenerativeComponents) but the standard is still evolving so adoption by the industry is limited. In architecture projects, as with most projects, the 3D CAD models are just one of many types of files produced that are important for curating the collection over time. From the 3D model many more specific 2-dimensional drawings are produced for particular aspects of the building (electrical, HVAC, floor layouts, etc.). There are also artistic renderings produced for clients – photorealistic images, photographs and 1 Second Life http://secondlife.com/ 2 Two major projects exploring 3D models from the engineering sector are the “Immortal Information and Through-Life Knowledge Management (IITKM): Strategies and Tools for the Emerging ProductService Paradigm UK Knowledge” (https://www-edc.eng.cam.ac.uk/kim/ and the Digital Engineering Archives project directed by William Regli of Drexel University http://gicl.cs.drexel.edu/wiki/Main_Page#Active_Research_Projects 3 Autodesk’s website http://autodesk.com 4 Dassault Systèmes website http://www.3ds.com/ 5 Bentley Systems website http://bentley.com/ 6 The Building Information Model (BIM) standard is being developed by the National BIM Standard organization, described at http://www.facilityinformationcouncil.org/bim/index.php 7 Heating, ventilation and air conditioning The International Journal of Digital Curation Issue 1, Volume 4 | 2009