Project Alcatraz

Like any other national park site Alcatraz needs to be maintained.  The National Park Service (NPS) and an army of volunteers operate, maintain, and ensure a safe, enjoyable visitor experience on Alcatraz for well over one million visitors per year.  Yet the effects of time, the elements, climate change, sea level rise, and seismic activity all take their toll on The Rock.  Alcatraz is changing all the time.  Understanding how Alcatraz is changing over time is a high priority for the NPS. 

In January of 2023 I started asking about the possibility of scanning all of Alcatraz with people I knew at the National Park Service (NPS) and my friend and colleague, former NPS park historian at Alcatraz, Dr. Jim Delgado PhD.  This led to a key meeting with the park archaeologist at Golden Gate National Recreation Area, Peter Gavette. 

I proposed a comprehensive survey of the entire island, including every building, inside and out using terrestrial and drone-based LiDAR, photogrammetric and multispectral sensors.  The resulting dataset could serve as a baseline that all future surveys can be measured against.  Peter and the NPS agreed, and we set to work.

Reality capture is an industry term that, as the name suggests, is a collection of technologies and workflows that can create this survey data with a high degree of accuracy.  LiDAR, laser-based sensors, shoot millions of laser pulses per second and generate 3d, colorized point clouds of whatever they “see.”  Photogrammetry is a process that allows anyone with any camera to take a series of photos of anything.  The photogrammetry software then stiches those photos together into a photorealistic model.  Both LiDAR and photogrammetry can be drone based, ground based, fixed and or mobile.

Following a nine month wait for permits to be issued and the protected birds to fledge, in early December 2023, a team I put together assembled at Alcatraz.  The team brought a collection of hardware and software that had never been massed before.  Drone based LiDAR, photogrammetric and multispectral sensors, terrestrial laser scanners, SLAM scanners, RTK GPS surveying gear, SPOT the robot dog, and an AMD supercomputer.  There were fixed wing, VTOL drones, rotor wing drones, a drone in a cage that can access confined / dangerous spaces, terrestrial laser scanners with a 2.5km range, two SLAM scanners that we walked, crawled, ran with, and even got into tricky spaces with it on the end of a long pole.  SPOT took the SLAM scanners into spaces contaminated with lead and asbestos.  All of this technology had never been deployed together before, anywhere.  No single tool or sensor could access every space.  We needed it all.

The Tools

If ever there was an example of highlighting the toolbox instead of the tool – it’s this project.  There has never been a gathering of all these sensor types before – simply because there was no other way to complete the project without using all available resources.  These sensors included LiDAR sensors from Emesent, Phoenix LiDAR, Reigl, Pix4D and Flyability.  The entire island was flown using drone-based LiDAR and the interiors were all scanned with terrestrial laser scanners and SLAM scanners.  The island was also flown with drone based MSI (multi spectral imaging) designed to measure chlorophyl in plants.  Drone-based photogrammetry was also flown over the entire island.  The Flyability E3 drone can fly into dangerous, confined, and contaminated spaces and capture video and LiDAR at the same time.  Boston Dynamics robot dog, Spot, with a LiDAR sensor on its back, also went into hazardous spaces where the rotor wash from the E3 would have kicked up asbestos and lead contamination.

The Supercomputer

When asked what the most important piece of technology during the project was, it’s a simple answer.  The AMD Threadripper PRO 7995WX workstation with 96 cores, 512GB RAM, and 12TB of SSD storage.  The data we have collected has just passed 4TB in size.  Postprocessing all of this data would not have been possible on our laptops. Limited access to fast Wi-Fi speeds ruled out using cloud-based options. Our only option was processing locally on a workstation with exceptional capabilities.

The Team

I have never witnessed, or even heard of, a cooperative effort like this before.  Team members set aside their day-to-day competitive concerns and focused on the project.  Another first.  This, to me, is one of the most profound parts of the entire effort and speaks highly of everyone on the team and the organizations they work for.

The Place / The Experience

Alcatraz is layered in history and much of it is unpleasant.  From the earliest native American inhabitants having their land taken away, the civil war, through two world wars, and ending with the prison closing in 1963, it seems every space has a less than pleasant story to tell.  The isolation cells in A and D Blocks are particularly nasty.  No light. Next to no human contact.  The bullet holes in the north gun gallery where the Battle of Alcatraz occurred, and where guards and inmates were killed.  The photos of 19 Hopi tribal members locked away because they refused to send their children to government boarding schools.  The cellhouse itself seems to echo with the sounds of the past.  Echoes of violence, madness, hopelessness, misery. 

Sleeping on Alcatraz for almost three weeks was an interesting experience.  You hear everything.  My team members’ every move, every bodily function, snoring, bad dreams.  The sounds of the bay.  Fog horns, wind and rain, a distant bell buoy.  I slept well once I secured a mosquito net.  The first night the bugs ate us alive.  I wonder if the inmates suffered as well?  We were billeted in D Block on Alcatraz where the worst of the worst were kept.  My cell number was 31.  The Birdman of Alcatraz was a few cells down in 41.  Many asked about ghosts, apparitions, etc.  No, just bugs and the noise of my team.  I was typically first to go to sleep and first up in the morning.  My routine settled into up between 4:30 and 5am and then in bed between 8:30 and 9pm.  The bed was ok thanks to my camping gear.  Too narrow.  Too short.  But ok.  I got used to it after a few nights. 

Getting up in the morning and walking through the darkened cellhouse to the public restrooms outside the cellhouse was filled with the sounds of the team sleeping.  I tried to imagine what it must have sounded like 70 years ago with 250 inmates.  Stepping outside of the cellhouse way before the sun came up presented me with a stunning view of San Francisco – when the weather was good.  A few times the city was socked in with fog, or pouring rain, or 40 mph winds and rain making that walk to the restroom more of a sprint.  The gulls would start their cacophony of bellowing, screaming just before sunrise.  I don’t think they liked waking up on the island and having us for company.  Cold water on my face.  Brushing my teeth in a utility sink and water fountain, then into the office to see about breakfast.  Meals consisted of what we brought with us.  Mostly freeze-dried camping stuff, oatmeal, etc.  Running down the 212 steps to the ferry to grab a hotdog became a bit of an obsession after a few days of cereals, etc.  I ate A LOT of ferry hot dogs.

There are not many who can say they slept in a cell on Alcatraz.  Fewer still can say they did it for 19 nights.  I’m grateful for the experience and I’m glad it’s over.

All credit for this effort goes to my team. I cannot thank them all enough. Without each of them this would not have been a success. I think I can speak for all of them by saying we hope our body of work will help maintain and preserve this iconic place.