Brunelleschi’s Dome

The city of Florence began building its cathedral, Santa Maria del Fiore, in 1296 as a means of establishing itself as a major European economic and cultural capital. But by 1418 the cathedral still had no dome, mainly because the massive hole in the roof presented a formidable engineering challenge.

Inaccurate Octagon

No one was able to develop a workable plan for building a dome nearly 150 feet across that would have to rest 180 feet above the ground on top of the existing walls, which were built to form an approximate octagon without a true centre. No one was certain if a dome could be built at all over the octagonal floor without allowing the masonry to collapse inward as it arced toward the apex. Moreover, the architecture prevented the use of traditional Gothic flying buttresses and pointed arches familiar to builders working at that time.

They also needed a way to support the dome while under construction, weighing tens of thousands of tons, and timber for scaffolding and templates to shape the dome’s masonry. Consequently, in 1418 Florentine authorities announced a contest for the ideal dome design with a cash prize of 200 gold florins for the winner.

Filippo Brunelleschi, a goldsmith and clockmaker, became the successful Florentine dome designer, but the engineers, architects and historians of today still do not agree on exactly how he constructed the resulting dome atop Florence's cathedral. Brunelleschi planned to overcome the building’s inaccuracies with a double layered construction comprising an inner and outer shell held together with brick arches and interlocking rings of stone and wood. The rings prevented outward expansion. Further innovation allowed the masonry to support itself during construction - Brunelleschi interlaced the bricks in a herringbone pattern as he built the domes from bottom to the top.

Graphic Potential

When National Geographic planned to publish an article about Brunelleschi’s dome, written by Tom Mueller and photographed by Dave Yoder, as their February issue cover feature, Senior Graphics Editor Fernando Gomez-Baptista spent more than four months on research and design work to create the supporting graphics.

“Usually I begin working on the graphics for an article about six or seven months ahead of publication, but this case was special,” Fernando said. “About a year ago National Geographic TV was working a documentary about the dome and I was asked if I thought that a feature on the structure had graphic possibilities for a magazine feature. The idea was that if we published a feature on the dome, the graphics would be an important part of telling its story. After a quick look, I saw a huge potential.”

Once the magazine decided to move forward with a graphic feature, he hired a researcher, Fanna Gebreyesus, to begin gathering information. He also needed to travel to Florence to see the dome and meet the experts. “Because my colleagues were already in there working on the TV special, I arranged my trip in less than a week to meet them and we were able to share contacts and resources. So essentially, work began nearly twelve months out from publication, but we spent a period of four months honing the final graphics,” said Fernando.

Florentine Specialists

“I did a great deal of  research in the few days before I headed to Florence, preparing questions, diagrams and drawings about Il Duomo - Santa Maria del Fiore’s dome -  to be confirmed by the experts. I spent five days in Florence where I met with three specialist architects, some of whom have spent their whole careers studying Brunelleschi's dome, who sketched for me their understanding of all the details of constructing and designing the dome.”

Fernando’s own background has given him some experience in creating architectural design graphics. He said, “Twenty years ago I worked as a freelance designer and did a lot of technical drawings. I also have some experience with technical drawing from a previous design work at the magazine. Two years ago, for another National Geographic feature, I worked on the graphics depicting the architectural details of La Sagrada Familia in Barcelona. I’ve also contributed graphics for Nat Geo’s features on Jerusalem and one on Gobekli, a temple in Turkey.

Fernando visited Il Duomo museum where the models attributed to Brunelleschi and the tools used in the construction are kept. A special part of the research was seeing a 1/5 scale model that one of the specialists was building in a park in Florence. Seeing this model helped him to better understand and visualise the structure of the double shell of the dome. “Of course I visited the dome itself,” he said. “Over the course of the week, I went four separate times and spent hours going up and down within the walls of the double shell and getting into restricted areas—a neat perk of doing this research.

To make the animation, hundreds of frames were drawn. This segment, which shows Il Duomo architect Brunelleschi walking, featured more than 100 frames.  Art: Fernando G. Baptista, NGM Staff

Back to the Drawing Board

“I took around 500 images of the dome and of the scale model and finally, with all of this material, I returned to Washington DC. The curious thing was that the more I learned about the dome design, the more questions I had. Instead of sophisticated engineering techniques like LIDAR scans, photogrammetry or survey, this project was carried out using observation and abundant, careful research.

“We had ongoing back-and-forth communications with our specialists, who helped us to verify every detail to ensure the elements were as accurate as possible. I also relied on their own resources - for example, architect Riccardo Dalla Negra has compiled plans, complete with diagrams and measurements and cutaways that proved invaluable. “

Fernando’s two resrearchers, Fanna Gebreyesus and Elizabeth Snowgrass, were critical to his work, particularly for an in-depth project like this one. They are responsible for getting information, checking that it is correct, and serving as an ongoing link with the experts. “The two researchers worked tirelessly on this project. They communicated with more than 15 experts and probably exchanged hundreds of emails to be sure we got every detail just right,” Fernando said.

“Making all the pieces come together - not only graphics but also text and photos - was a big process as well. The overarching idea was to create an informative package with photos, text and graphics, trying to cover as much as possible without repeating the information.

“The writer, Tom Mueller, shares a fascinating narrative that offers a background of the times, of Florence, and of the many facets of Brunelleschi, a fascinating character and a technical genius. Dave Yoder’s photographs provide a modern context of this incredible structure. And the graphics themselves, which look into the construction of the dome itself, were a group effort, right down to the carefully crafted captions.”

600 Layers

Fernando works with a mixture of traditional tools and a computer, always starting with a pencil sketch, although sometimes his early sketches are fairly abstract. Then the main idea is embodied in a computer sketch, which he makes using Adobe Illustrator.

“For this particular graphic,” he said. “I also made a small-scale model with cardboard, which I photographed to help determine the best viewpoint, the real proportions and how the light fell on the dome. For me, understanding the light is very important because that's what makes objects work visually on the page and it gives a sense of nuance and texture that is difficult to achieve if you’re just looking at a 3D computer model.

“Then I add colour and details to the picture and refine it with several layers of texture using Photoshop. I make the texture layers with watercolour or by scanning and overlaying different materials, such as paper. I also use Illustrator to add the technical lines and secondary diagrams. For the Il Duomo illustration I created more than 600 layers in Photoshop which I merged and made into a single graphic.”

Fernando worked on the graphics and the animation for about three and a half months, but emphasizes that the researchers, staff and interns helped him with so many parts of the illustration. He said, “It was like a big puzzle of information, illustration and text, and what you see as the final product was shaped dramatically over the course of those months. In fact you’ll notice the long list of names in the credit line for all the graphics.”