BIM Handbook: Chapter 3 - Interoperability
According to Merriam-Webster, interoperability is defined as “the ability of a system to work with or use the parts or equipment of another system” [1]. In terms of BIM, it is the process of exporting/import data between applications that describe the same object. The National BIM Standard (NBIMS) is being undertaken to standardize the data required for particular exchanges [2].
As described in Chapter 2 there are three types of BIM Applications: as tools, as platforms, and as environments. Using interoperability, you can address all three of these but on different levels by means of translation. Using BIM’s in-place tools, the user is informed of the results of the translation in case and of the copying needs to be checked for due diligence. Again, all this depends on the nature of the exchange format used.
2D CAD is one of the simplest exchanges and most common exchange format used and even then is there are different applications, specifically pairing design with monetary billing and breakdown of materials. During my time at PWD as a co-op, although there are paired programs to calculate these quantities, I had to calculate the engineering estimates by hand. When the design was initially submitted, the links to the quantities may have be working, but in most cases, when the design was modified, the program link between the two was not always updated properly. Once the schema and schema language are defined, the exchanges between programs can be classified in three ways: direct links, proprietary exchange format, or public product data model exchange format [2].
Going back to 2D vector formats, the common AEC Applications would be .DWG (AutoCAD) to .DGN (Microstation). At my most recent co-op in the private sector, I had a lot of work that involved converting between the two for various details and cross sections. Although a tedious process, overall it is effective in translating the same information into a different application format. Most times I ended up following the process that AutoDesk includes on their website forum [3]. To perfect this process, places like the IFC have come to fruition.
The IFC or Industry Foundation Class is a schema that was developed to define data format for a more consistent process and make data exchange easier. In the most current version (2010), there over 800 entities, 358 property sets, and 121 data types that can be easily used in any AEC application. Trying to reflect the plethora of intricacies using in building information is no easy task, but I believe the IFC is off to a great start.
References:
[2] Eastman, Charles M. BIM Handbook: A Guide to Building Information Modeling for Owners, Managers, Designers, Engineers, and Contractors. Hoboken, N.J: Wiley, 2008. Web.
[3] https://forums.autodesk.com/t5/autocad-2010-2011-2012/convert-dwg-to-dgn/td-p/2622921 EDIT: Comments lefts of Kai's and Cathelene's orignal post
Totally agree with you Danielle, During my first co-op, part of my job was to survey hole patterns in fabricated steel girders and then use that data to detect eccentricities with actual hole locations in CAD drawings done using MicroStation. The data obtained from the surveying instrument was not compatible in MicroStation hence those data were manually plotted and compared with actual CAD drawing which was time consuming and unnecessary repetitive work. During my second co-op, I did a similar surveying job however this time a software called PC-DMIS was used to import data from the surveying equipment which was compatible with MicroStation hence it saved me from doing the trouble from the previous co-op.
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