AEC

AEC Tech News #159

19 Jan, 2006 By: Michael Dakan


Cadalyst AEC Tech News

So Many Acronyms, So Little Time

NIST explores 3D file-exchange formats: VRML, CIS/2, IFC, STEP and more

NIST (National Institute of Standards and Technology) has a section on its Web site titled, “CIS/2, IFC, VRML and X3D Product Data Standards Research for Structural Steel,” which summarizes the state of interoperable 3D file formats currently available. The page includes many links to resources and information about viewing and working with 3D content. It offers extensive background about the CIS/2 format, which has become a relatively new standard information-exchange format for structural steel models -- and could potentially integrate with other file formats.

VRML
VRML (virtual reality modeling language) is the oldest 3D modeling file format around -- it has been used for all sorts of 3D modeling for many years, including the earliest immersive computer game environments, as well as various scientific and engineering modeling and viewing applications. Many software systems still support it, including some CAD and rendering programs that export directly to VRML World files (WRL).

NIST offers several links to sites where you can download tools for working with VRML, including file converters and viewers, many of them free. Most viewers operate in Web browser software and are automatically supported in your browser if you’ve installed the correct browser plug-in for WRL files.

CIS/2
CIS/2 is a relatively new file format developed to facilitate data exchange among various types of software for working with construction structural steel, including analysis and design software and 3D modeling software. AISC (American Institute of Steel Construction) has adopted CIS/2 as a standard data-exchange format. CIS/2 also is the standard data import and export format in most structural-steel programs.

The original CIS (CIMsteel Integration Standards) file format was developed as a standard for CIMsteel (Computer Information Manufacturing for Constructional Steel) information, which originated in Europe to facilitate “bridging the information islands” -- that is, the various software applications in use at the time. CIS/2 denotes the second version of the standard, which is in use today.

IFC
IFC is a massive undertaking by the IAI (International Alliance for Interoperability). It attempts to describe a database structure schema for a complete building information model. It is similar to CIS/2 in that it’s an XML data schema, but CIS/2 is aimed at only the structural-steel components of a building and was developed to smooth the information flow between various structural-steel software applications. IFC is intended to eventually incorporate all elements of the building information model, including structural steel.

Because CIS/2 and IFC have been developed independently and have different legacies and histories, the two are not integrated and interoperable at this point. But CIS/2 developers and IAI have committed to work together to unify the two data schemas in a single data format in the near future.

STEP
STEP, also known as ISO 10303, is the ISO (International Standards Organization) standard for sharing data among all segments of the construction and manufacturing industries. ISO 10303 is currently an “umbrella set of standards” for data, meaning that it encompasses a number of building element description standards to form the complete ISO building and manufacturing information model. IFC and CIS/2 are being developed using many ISO standards and methods.

The hope is that eventually the CIS/2 structural-steel information will be incorporated into the overall IFC model, and both will be rolled into a version of an ISO 10303 AP (application protocol), a process that will likely take ten years. At that time we will reach acronym nirvana, and most of this alphabet soup can fade away. We will finally have that fully integrated 3D data model for buildings that everyone has talked about for more than a decade.

Adobe U3D and Google Earth KML
Also shown on the NIST site are some demonstrations and information about a couple of other 3D file formats that have come on the scene recently, sparking some interest among content creators who want to incorporate and view 3D content.

Adobe U3D is that company’s interactive 3D model format that can be inserted into an Adobe PDF using Adobe Acrobat 7.0 Professional. PDF recipients can then view and interact with the 3D data using Adobe Acrobat 7.0 or the free Adobe Reader 7.0. This should be a very useful tool for transmitting and using 3D content among design professionals.

So far, few companies have developed U3D translation and creation tools. However, the potential and popularity of PDF files as a standard information-exchange medium in many industries, as well as the enhanced functionality found in Acrobat 7.0 Professional, could well encourage more support for U3D over time.

Google Earth and Google Maps are generating a lot of interest on the Web, and several program developers have created file translators to bring 3D models into Google Earth KML format files. KML is the file format used to save Google Earth views, or folders that contain places and imported data, which comprise My Places in Google Earth. Users can place a building model, for instance, in any location in the world represented by a Google Earth 3D image to view how that building would appear in its real-world setting. Among the latest translators I’ve run across is a plug-in for inserting AutoCAD models into Google Earth: Avatech Earth Connector is available from Avatech Solutions.


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