Alban Denoyel allowed us to repost an amazing article on his first drone 3D capture experience.
Alban Denoyel allowed us to repost an amazing article on his first drone 3D capture experience.
As some of you know, I’m a big advocate of 3D capture. I believe it’s the next big capture medium. I 3D scan a lot of things, you can see some of my favorites here. When I first heard about drone 3D capture, with examples showing up on Sketchfab in the early days, I immediately wanted to give it a try. It took me a number of years to get to it, and I finally just made my first drone 3D capture! It’s not a capture of a random thing, it’s the capture of the latest mural pasting by JR, one of my favorite street artists. This is a story about JR, photogrammetry, and drone 3D capture.
JR
JR is a french artist known for his massive collages of portraits all over the world. My favorite work from him is the guy walking on Flatiron plaza, which made the cover of the New York Times. His latest work, called “Guns in America”, is a collaboration with TIME magazine, about what hunters, activists, parents, students, politicians, police officers and other Americans say about gun ownership and gun violence in America. He made a huge mural of it on an disused building in the Navy Yard, right in my own street in Brooklyn. It was the first time I saw the actual process of making this happen, with a crate and people spending hours pasting huge pieces of paper on an immense wall, which got me to realise how intense the process was. As soon as I saw that, I naturally wanted to make a 3D capture of it.
Photogrammetry
My go to 3D capture method is to take a number of photos with my (regular) phone, and process them with a photogrammetry software. Photogrammetry is simply the process of stitching a number of overlapping photos together, it does automagically all the hard work of reconstructing them into a 3D file and texture. It’s longer and more tedious than using a depth camera (like the kinect or the depth sensor of the iphone X), but the resolution is typically much higher, and the capture part is hardware agnostic (any camera can do the job). There are a number of photogrammetry software out there, my go-to solution is Photoscan, which is in the high end of software which can run on mac. So I did do a first capture this way, just using my iPhone (6s) and 50 or so photos to make a capture, below. As you can see, the capture is not great because it’s all done from the ground, so I had to find something better. Plus the pasting was still in progress and some of the mural was missing.
“Guns in America” collage by JR by alban on Sketchfab
My first attempt, using just my phone from the ground
Drone 3D capture
The solution was naturally to use a drone to be able to shoot from above. I had never done it myself, but we had a DJI Phantom 4 at the office, and Corentin from my team had made a few experiments with it (shooting the house of our team event last year, and a building from the Bushwick collective). Drone photogrammetry is not too different from regular photogrammetry, it’s just that the photo input is taken with a drone. There are a number of specialized aerial 3D mapping software like Pix4D, helping you define a capture path, and taking care of the 3D reconstruction. In my case, I just manually took photos 1 by 1, and processed them with Photoscan. I synced with Marc, JR’s studio manager, who asked the building owner for permission to do it, and was able to get on the building to make it happen. I took 82 photos of the mural, you can see below a screenshot of Photoscan showing the different camera angles:
Photoscan showing the 82 camera angles of my 3D capture
And here is the final result. The texture is 8k and the model is 500k polygons, so it might take a little while to load.
Guns in America by JR & TIME by alban on Sketchfab
My first done 3D capture
As you can see, it’s not quite perfect yet. I wish I had taken many more photos from more angles, to have a better end result. I’m still pretty happy with it given it’s my first try, and can’t wait to make more!
Alban Denoyel, 3D Artist
The article was originally published on Medium.