3D Scanning Paris' Catacombs with iOS LiDAR

About

I’m the co-founder and CEO of Scenario, a newly founded startup working on location-based metaverses (running stealth for now). We’re based out of San Francisco, Paris, and Santiago de Chile.

Prior to this new venture, I was the co-founder and CEO of Redbird, a drone-powered analytics provider for the construction industry (later sold to Airware). I spent 8 years in the drone industry (2012-2020) and witnessed the evolution of both aerial capture using drones and all the associated 3D reconstruction techniques (both photogrammetry and LiDAR).

LiDAR scanning

Redbird was focused on enterprise use cases (construction, mining, utilities). Drones were the main capture tool but I got interested in ground-based mobile scanning early on. When Apple launched the LiDAR sensor on their devices in mid-2020, I immediately felt this was the start of a profound revolution for consumer-led 3D scanning. I joined Alban in the “1scanaday” challenge in early 2021, and I haven’t been able to stop scanning my environment ever since. I live in the Bay Area and San Francisco is an incredible playground for scanning.

Right now, my daily scans are mostly a passion (similar to photography). However, I see 3D scans becoming completely ubiquitous when our devices (phones and wearables) will constantly capture their environment and become spatially aware. This will help build a 3D map of the world, which will lay the foundation for ubiquitous augmented (or mixed) reality.

The catacombs project

Regarding this “catacombs” project: I was spending a couple of weeks in Paris and called a “cataphile” friend (i.e., an experienced urban explorer visiting the catacombs for 15+ years). I had been there a few times before, and I asked if he could take me down below so we could scan some of the most interesting places. That’s how it started. I would just insist on this: the catacombs are no place for inexperienced “tourists”. Cataphiles are a very special type of people. Most of them have a deep knowledge of the catacombs, they show passion and respect for the place and care about preserving it for the future.

I use the iPhone 12 Pro with various scanning apps, including Scaniverse, Polycam, Sitescape, and 3DScannerApp. The output is either meshes or point clouds, depending on the purpose of the model. During the “catacombs project”, I also used a rig with two powerful 3,000 Lumen LED lights attached. View the TikTok post.

Challenges

The catacombs are pitch black. You have to plan your capture in advance, because you only see what’s in the beam of your lights… Also, the place is exiguous and doesn’t always allow for a perfect scan. We had to re-do some captures. This is why I love LiDAR (vs. photogrammetry). The processing was done immediately on-device with no internet connection needed.

Sketchfab

Sketchfab is the easiest way to save different models captured with various apps (or my phone would blow up). It’s also the easiest way to slightly edit the models and share them widely. The editing features (filters, lightning, etc.) are very valuable since no capture is perfect.

Getting started with LiDAR scanning

If you want to get started, just buy an iPhone/iPad with the new LiDAR sensor, download some scanning apps (most of them are free, by the way), and start scanning. It’s the cheapest and easiest way to start. It’s super easy, fun, and most people around you will be blown away by your results. Then get into photogrammetry to generate higher quality models. Practice, practice, practice.

Looking ahead

3D is just inevitable (like digital photography was inevitable back in 2000). 3D will completely change the way heritage organizations communicate to their local and remote audiences. VR visits will be commonplace. “AR guides“ will help visitors get additional information about the places they visit (like audio guides do… but visually, in 3D).

A favorite model on Sketchfab

I was pretty impressed with the Sainte Chapelle in Paris! That city has amazing scanning opportunities by the way. This scan is near perfect with so many details of the stained glass windows.