“So, there, with just a brief look at this building, you immediately understand that this building has had a history. It has been reconstructed and rebuilt in different designs and different periods and that's what we are here to study.”
The study is using the latest techniques in 3-D mapping. The process, known as structure-from-motion, involves taking thousands of digital photographs of the baptistery and then using them to build up a virtual recreation in three dimensions.
“We can make a very high resolution texture out of the building that the archaeologists can use for really close up interpretation and analysis of the building,” says Håkan Thorén of the Swedish Heritage Board.
“I think it is possible that we have so far taken about 4,500 pictures of the building. And we still have some to take. So I think we'll end up with about 6,000 images that we use to compute a 3-D model out of the building.”
The team sees the baptistery project as particularly significant, describing the building as “one of the most important Christian buildings in the world.” Founded by Pope Sixtus III in 440, it is built upon an earlier structure dating from the time of the Emperor Constantine in the previous century. In fact, it’s sometimes claimed he was baptized in its octagonal font. For many generations afterward it was the only baptismal font in Rome.
“It was built together with the Lateran cathedral, which is also still standing, but the ancient building is invisible because it is covered by Baroque decoration, while, as you can see, the Lateran baptistery is not,” says Olof Brandt.