Time Traveling Storytellers: A Conversation with Holygon

Many SketchUp users have an innate appreciation for historically significant structures. We may find ourselves pouring over pictures of the Greek Acropolis or staying up late to watch documentaries that hypothesize how our ancestors constructed their magnificent cities.

Our friends Anders Lyhagen and Felix Heuman found a way to take that same shared passion for the past and combine it with their skillful use of SketchUp. Their design firm, Holygon, specializes in creating historically-accurate digital models for visual and 3D printing applications.

Holygon recently presented their workflow, along with a section of their largest 3D model to date, at 3D Basecamp 2018.  We asked them to share their story with the entire SketchUp community.

Holygon’s latest commission: a printable SketchUp model of the Swedish city of Landskrona. Containing 35,000 parts in scale 1:1,000, it is Sweden’s largest public color-3D-printed city model.

What inspired you both to begin Holygon?

Anders: In the hot summer of 2013, I was relaxing in my orchard on the island of Gotland in the Baltic Sea. One day, apples began bombarding me from above. Seldom slow to notice Mother Nature’s attacks, I thought I probably ought to do something about this. I downloaded SketchUp Make and modelled an apple scratter for cider making: my very first 3D model.

Felix: During this time, I was busy drawing the structural glories of the past in Rome and Paris. I had received a grant to study classical architecture. Once back in Sweden, I showed Anders a sketch of a classical temple I had designed, asking whether it would be possible to recreate it in 3D. Anders replied: "I made an apple scratter, so why not a Tuscan temple?" One week later, our world had changed... we had a virtual standing temple we could not stop staring at.

After modeling for some years, we perfected our technique and noticed a commercial demand for printable 3D models. Thus, we launched Holygon–a company specializing in making printable, state-of-the art 3D models, especially of cities and architecture. Our latest finished project is Sweden’s largest full-colour-printed city model, commissioned by the city of Landskrona. All thanks to being hit by a falling apple.

A visualization of Landskrona modeled in SketchUp. A close-up of the final 3D-printed version of Landskrona.
From SketchUp to the 3D printer, Holygon’s detail wows at every turn.


Which one of you spends more time modeling in SketchUp, Felix or Anders?

Felix: I’m responsible for visual design.

Anders: I handle programming. But we both very much enjoy dual, hands-on modelling, which is effective for progress. If one is having a lousy day in 3D space, the other can always cheer him up with bad jokes that make nerds smile.

Felix: In practice, we tend to model in bursts. We are rapidly approaching 10,000 SketchUp hours, which has occasionally led to nights spent sleeping on the office floor.

You've really mastered the art of modelling complex architectural detail within SketchUp. Can you talk about this process? What's the hardest part of modelling classical elements?

Classical architecture is almost everywhere doubly curved. This means that surfaces simultaneously bend in two different dimensions, smoothly and irregularly. Even the apparently flat crepidoma (stepped platform) of a Greek temple is intentionally bulging both inwards and upwards. Double-curved elements, along with high quality 3D printing, require polygons sometimes numbering in the millions. Sometimes the hardest part is waiting for SketchUp to finish computing geometry operations.

The drama is in the details. Holygon’s mastery of double curves brings classical Greek architecture to life.

Can you tell us about your workflow?

We always start with quality references. Searching may take weeks, but having the highest-quality measured drawing is critical.

Once we have the reference, we discuss how we’re going to achieve a certain shape and the tools we’ll need to draw it. This all happens before even turning on the computer. We then simulate the upcoming modeling process in our heads.

Once in SketchUp, we try to stay modeling in 2D as long as possible. To bring designs into 3D, we extract copies of the 2D outlines and make them three-dimensional by push-pulling, sweeping, lofting, flowifying, and so on. Extensions are employed liberally. We often design in three or more concurrent SketchUp instances to keep files light and nimble while running SketchUp’s internal checks.

Holygon’s paper sketch of a stylized artichoke finial is imported into SketchUp, carefully 3D modeled, and finally rendered in gold.

You recently presented a section of your overwhelming 3D printed model of Landskrona at SketchUp's 3D Basecamp. How do you approach such a daunting modeling project?

Zooming in, we can see every pain-staking detail included in Holygon’s 3D printed model.

Being commissioned to create Sweden’s largest color 3D-printed city model was honoring and obligating. Our initial proof of concept proved we could do it. The daunting challenge was the time frame: three months. When we delivered the final model under deadline, the Landskrona commissioners smilingly said they were surprised we managed to pull it off.

Admittedly, we have a secret weapon: Holygon’s proprietary city-building extensions. These extensions are heavily specialized, growing beasts of code. They mainly do two things: speed up accurate 3D modelling from point cloud data, and batch-manage geometry.

Other “magic button” approaches, like auto-generating surfaces from point clouds remain underwhelming. Computers are bad at interpreting ambiguous data; bad at meaningful simplification; and, bad at aesthetic judgement. Unfortunately, this is precisely what good city models need. Holygon’s approach is essentially manual. Our customers feel that the premium quality of the results is worth it.

How many hours of work have gone into this model?

Beyond 1,000 hours. It’s a labour of love.

Can you tell me why documenting historical architecture in a digital 3D environment matters? Why should people take interest in the digital humanities?

Buildings are time travelers. Aging yet contemporary, they invite us to touch and feel the past. Documenting historical environments teaches us the achievements of our forefathers, appreciation for their technical skill, and a sense of continuity with mankind. Reconstructing lost environments in 3D instructs us to pay attention to the historical past while recreating it.

Reconstructing lost environments in 3D instructs us to pay attention to the historical past while recreating it.

Classical architecture is a suitable style for digital composition; it's based on repetition of identical parts, it's symmetrical along multiple planes, and it often employs rational ground plans. These factors facilitate historical reconstructions, for even if no part survives in its entirety, fragments complement each other.

Want to dig deeper into Holygon's process? Felix and Anders share their nine-step workflow.