Modelling in a Digital Dimension

27 January 2010 (Last Updated January 27th, 2010 18:30)

The art of traditional 3D modelmaking by hand is giving way to an array of new digital technologies. Lisa Delgado takes a look at how they can be used to boost efficiency.

KPF interns used to be all too well acquainted with the task of meticulously cutting cardboard to make models by hand. These days, however, they're working on digital models like everyone else, and using a 3D printer to create precise replicas of those computer-based creations, according to James Brogan, the company's director of firmwide technology.

With the rise of digital design, it's no wonder that physical modelmaking is increasingly going high-tech, too, boosting efficiency. Some firms such as KPF have invested in relatively affordable 3D printers and made them an integral part of their design process; others, meanwhile, haven't taken the plunge to buy their own machine, but when they need highly detailed and durable models for exhibitions or client presentations, they commission specialists to make models using higher-end rapid-prototyping techniques such as selective laser sintering (SLS) and stereolithography (SLA).

Printing processes

All of these technologies rely on additive manufacturing, which builds up objects layer by layer, replicating cross-sections of a digital model. Some companies, such as KPF, use 3D printers from Z Corp, which have printheads that spread binder over layers of powder to create models in a matter of hours. Z Corp's technology, which is similar to inkjet printing, was first developed at the Massachusetts Institute of Technology. By comparison, SLS and SLA tend to be slower and more costly, but produce models that are stronger and can therefore have finer details, and are better suited for postprocessing.

"3D printers can create precise replicas of computer-based creations."

SLA machines typically employ a UV laser to harden layers of photopolymer resin, and one advantage of SLA is that it can create transparent parts if desired. SLS machines, meanwhile, use a laser to fuse powder made of materials such as nylon. The powder supports the model as it's being built, obviating the need for extra support materials, making SLS good for complex structures, according to Stuart Offer, sales manager of rapid-prototyping firm 3T RPD.

Naturally, companies with a strong bent for digital design have been more prone to embracing the technologies early and enthusiastically, as a convenient way of accurately replicating CAD models in physical form. Thom Mayne initiated the purchase of Morphosis's first Z Corp printer in around 2001, says IT director Marty Doscher. "The primary use is as a kind of 3D sketch paper," he says. "It's a medium for the design team – even from day one on projects, when we're doing conceptual design – to really quickly and through rapid iterations study [form] and massing at a schematic level."

KPF also uses its in-house Z Corp printers extensively for early study models, but it has found that a 3D print can also be quite useful in explaining a design to clients. "The tangible qualities of it, I think, are really important – that a layperson can pick it up and move it around," says Brogan, adding that clients sometimes grow so enamoured with a 3D print that they ask to keep it.

Despite the advent of in-house 3D printers at KPF in 2004, the need for traditional modelmaking hasn't gone away, says Brogan. Combining techniques is quite common, and sometimes, for example, a rapid-prototyped building or element will comprise just one component of a larger model that's partly made by hand. And although they've improved incrementally over recent years, the technologies still have a way to go. Architects are still waiting for the breakthrough that combines the speed and low cost of a Z Corp printer with the strength and polished look of models made with techniques such as SLA and SLS.

Highly anticipated but also still elusive is the day when architects will be able to use related technologies to rapidly manufacture full-scale buildings. "Formula One cars use a rapid-prototyping system, ie., depositing material, to produce actual components of racing cars very, very quickly," says Cristiano Ceccato, an associate at Zaha Zadid Architects. In the future, perhaps architects will be able to do something similar, but, says Ceccato, "I think it's very early days."

Foster + Partners, Central Market, Abu Dhabi

Z Corp's 3D printers can create models in colour, so Foster + Partners took advantage of that to display solar data for tower façades in the Central Market. First, the architects used environmental-analysis software to create a colour map of where the sun and shade would fall on the façades to help determine the best design to maximise views from within, while also creating overshading and figuring out the best spots for placing photovoltaics.

Using custom programming, they mapped those colours onto CAD data in Bentley MicroStation. Next they changed that CAD data into STL, the format needed for printing, and created the physical model. "If you put that model down with a client or any consultant, it's much easier to understand than just looking at a rendering that displays the analysis through a typical colour gradient," says Xavier De Kestelier, associate partner at the company's Specialist Modelling Group.

"Z Corp printers have printheads that spread binder over layers of powder to create models in a matter of hours."

Morphosis, Cahill Center for Astronomy and Astrophysics at the California Institute of Technology, Pasadena, US

Morphosis delights in uncommon geometries, but sometimes their complex designs aren't easy to portray. A 3D section model helped the architects to visualise and explain a labyrinthine atrium stairway area in a university building. The architects began by slicing up their digital 3D model in Microstation, to divide it into parts that would fit into the printbed of a Z Corp printer in their office, explains IT director Marty Doscher. Working further in Microstation, they thickened certain surfaces and deleted some fine details, so the physical model would be strong enough not to break.

Once they printed the model, they found it proved helpful for architects and contractors alike in understanding how various parts of the stairwell area would go together, and Martin Bros, which performed the metal framing and drywall work, kept it in its field office for reference.

DeltaSync, Floating Pavilion, Rotterdam

With a tight two-week deadline to create an exhibition model of this floating pavilion, DeltaSync turned to rapid-prototyping specialist Freedom of Creation (FOC). DeltaSync creative director Bart Roeffen prepared the Maya model for printing by ensuring that it had volumes, not simply surfaces, and that no parts that would be too small to print. FOC oversaw the preparation and made some refinements to the digital model before a manufacturing partner did the actual SLS.

Water is difficult to portray in a static model, so Julian Sing of FOC came up with the idea of using animations of water that play on a screen that the model sits atop. Harbour sounds add further realism, and an onscreen information display helps educate exhibition visitors about the pavilion.