Thread by @emmanuel_2m

So last WE, I went down into the Catacombs of Paris. If you're not familiar, it's an insane anthill-like network of 200 mi. of galleries and chambers, centuries-old, 60 ft beneath the surface. @NewYorker wrote about it in 2019: newyorker.com/news/dispatch/…. Here's a short story.

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The goal was to 3D scan as many places as possible, using only the iPhone 12 Pro/LiDAR (and two powerful LED lights). And so we spent 12 hrs underground, walking (or crawling) more than 20 miles, and scanning 30 different places using @Scaniverse, @PolycamAI, and @Sitescape

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All scans were uploaded to @Sketchfab and the whole series is available here: sketchfab.com/edemaistre/col…. Interestingly I was able to process all the scans immediately on the device, down below (without service). Cool way to demonstrate the power of LiDAR scanning w the iPhone

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This provides an interesting 3D view of a hidden and secret part of Paris that very few people will ever visit. It's not quite legal and it can be pretty risky. This is the realm of the "cataphiles", experienced urban explorers cultivating a unique and secretive culture.

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Here's a scan of some spiral entrance stairs. Scanned with @Scaniverse, uploaded to @Sketchfab: skfb.ly/o66Gy

Entries into the catacombs are pretty rare, often locked, and always kept secret.

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This is the "Fontaine des Chartreux", an underground fountain built 200 years ago under a former Carthusian monastery. @Scaniverse: skfb.ly/o66KN. Also scanned with @SiteScapeAI as a point cloud: skfb.ly/o66KP

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Another nice place is the "Salle des Fêtes", also called "Salle du Cochon", a room where explorers gather to party or just take a rest. Captured with @Scaniverse: skfb.ly/o66GH. I met a famous TV journalist right there (won't say who :).

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The catacombs are home to old shelters and bunkers that were used in former conflicts (especially by the German Luftwaffe and then by French Resistance). Here's an old nuclear fallout shelter ("Abri Falco"), that could host 100 ppl. W. @Scaniverse: skfb.ly/o66JZ

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Catacombs were originally ancient underground quarries. After 1770, ossuaries were created to eliminate the city's overflowing cemeteries. 6 million people are buried there. This scan is the "Carrefour des Morts" (crossroad of death): skfb.ly/o66NL (w/ @PolycamAI)

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"Cataphiles" like to create their own rooms. We stumbled upon this little room called "Our Lady of the Catacombs" with benches, an altar, and a wooden cross. Maybe some underground masses were celebrated here. With @Scaniverse, on @Sketchfab: skfb.ly/o66N8

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Some places are REALLY tight. It's not for claustrophobic people. They are called "chatières" (only a cat - "chat" - can squeeze in). This one was 12m long and 50cm high. No turning back is possible. Scanning it with @Scaniverse was a challenge! skfb.ly/o66GV.

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Check out other amazing 3D scans on the @Sketchfab collection (skfb.ly/o66XP). I've met a couple of other "scanners" that night. One wants to create a whole scan of the place. Another one is thinking about a VR game. Who knows what's next with this technology...

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