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Mind your language

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architech - Will a single system ever be established to allow the movement of CAD data between different file formats?

Towards the end of the 19th century, a chap called Zamenhof decided that the creation of a new and universal language could reduce barriers between people by not favouring any one single people or culture.

Not wanting to waste any time, he promptly invented Esperanto.

Since then others have followed suit, and in the CAD world the Drawing Interchange Format (DXF) was developed for overcoming the hurdles encountered when trying to move CAD data from one proprietary file format to another. But in a world where the reuse of CAD data is now recognised as paramount to the success of collaboration, the dumbing down of data courtesy of the DXF 'smash and translate' process is no longer acceptable. Furthermore, as CAD models can now hold additional non-graphical information about geometry, it is desirable that this information also travels with the geometry when moving from one application to another.

Foreseeing this need, a group of people came together in the early '90s to form the International Alliance for Interoperability (IAI).

The plan was to create a new universal language for exchanging CAD data, and the result of their efforts to date is the Industry Foundation Classes or IFC descriptions. IFCs describe objects, rather than simple geometry like DXFs, and the IFC language is completely open to all. The latest incarnation of IFC is version 2x.

It can move data between applications for the following processes:

lstructural analysis;

lconcrete and steel structures;

lHVAC design and performance simulation - electrical design;

lpiped services;

lfacilities and property management.

This kind of inter-disciplinary data sharing is most certainly the way forward for moving 3D models between diverse systems, but I fear that another independent file format cannot be the way to go. I spoke to John Mitchell of Graphisoft, who is championing all things IFC, to get a better understanding of the IAI and the projects where IFCs are being used. One such project is in Singapore, where the equivalents of our building-control and planning departments have now mandated that all submissions be made online using IFCs.

However, the Singapore government's choice to mandate IFCs was not something that happened overnight. John Mitchell explained that the Singapore government first tried to mandate MicroStation and later AutoCAD, but both attempts to standardise the submitted files failed, allegedly for two reasons: the community was unhappy at the software application mandate; and the applications were not sufficiently robust.

Then, three years ago, the Singapore government joined the IAI and changed its mandate from DWG to IFC. Today the 13 building agencies are able to share the data submitted and the reports extracted from the models, leading to better intercommunication between departments.

Furthermore, with just a single submission, as opposed to the 13 required before, consultants' workload is also greatly reduced.

These submissions are now also made by logging on to a central IFC server, where the data is checked for consistency and integrity, and a report returned to the sender. While the Singaporeans seem to be leading the way, there is a groundswell of others following in their tracks. In the US, the General Services Administration (possibly the largest building owner in the world) has passed a motion stating that after 2006 it will only accept CAD data in IFC format. In Norway, Germany and France other government departments, construction companies, designers and savvy clients are also sharing data the IFC way.

Mitchell summed up a stimulating and enlightening conversation by saying that, as pressure is building for change in the industry, he expects this year to see an IFC explosion. My scepticism reminded both of us that in 1994 I was visited at my office by an exponent of the then recently formed IAI, who told me that within three to five years the whole industry would be working with IFCs. Ten years later, most people are still quoting the same figures. Sometimes I think being different is simply not enough (you have to be better too), even when your motivation for creating something different is to remove the differences that cause the problems in the first place.

I am not convinced Esperanto has achieved the levels of usage and acceptance within society that Zamenhof had imagined. Indeed, if you search on Google for 'Beckham' you will receive 50 per cent more hits than you would if you searched for 'Esperanto'. But what of the IFCs? Well, again using Google, 'DWG' returned nearly 900,000 and 'DXF' nearly 700,000, but ' IFC2x' managed a meagre 3,500 hits.

But the IFC is still young in comparison to the others listed, and somehow the charismatic Mitchell left me thinking that we have not heard the last of IFCs. I do hope he is right. Anything that effectively levels the playing field, and enables CAD users to vote with their feet where vendors are concerned, can only be good news for us all.

Joe Croser can be contacted via email at joe@croser. net

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