APPLIED DRONE PHOTOGRAMMETRY
APPLIED PHOTOGRAMMETRY
Generating the first successful point cloud is arguably one of the more exciting moments after buying a drone, especially as an architecture student. Finally, something useful to act as a stepping stone for the upcoming design.
From the simple to the more complex, here are some reasons to consider photogrammetry for your practice as a student, freelancer, or even a practicing professional.
3D OBJECTS (trees, rocks, custom elements)
Small objects are a good start at the beginning of your photogrammetry journey. They are fast to process (no need for hundreds of images), in proximity (less stress about dropping transmission connection), and easy to integrate in a design.
Recently I scanned the International Primary School in Montreal, and there were several large rocks at the main entrance which needed to be temporarily displaced for site work, and later potentially relocated and reordered . Exact location, sizes, and orientations are incredibly easy to obtain. At the end of the day, each stone became a separate mesh object which could be placed and rotated based on the design proposal.
Needless to say that once you have your 3D object in place, rendering is a piece of cake… a realistic piece of cake.
SITE PLANS & MAPS
It may vary between architecture schools, but during my masters, we had to spend a lot of time understanding transects of places in Canada we never visited. This kind of research requires a lot of digging into GIS archives and compiling maps on top of each other in order to make sense of a particular area. Drone photogrammetry, and yes, I am sure it isn’t photography, comes in handy as it can generate a lot of the information we need. Taking several hundred photos from a bird’s eye view allows you to generate orthomosaic images (simply put a high-resolution version of Google Maps in Satelite View) and a 3D topography. Needless to say that this type of information, especially in 3D is useful in the initial stages of design: understanding the surroundings and mapping the existing conditions.
VR
This was a new one for me. It turns out the pipeline from taking the drone photos to being inside a 3D model in VR is quite straightforward. It is so straightforward that 90% of it can be automated in Metashape. In my master’s, I had the opportunity to explore and develop a project in Wadi-Salib, a neighbourhood in Haifa, Israel. War had left the area devastated and in ruins. One of the Israeli professors had sent us 800 drone photos of the area which made it possible to generate a fairly detailed and textured model. Mind you, since the model is coming from a drone, the resulting texured mesh is to scale and properly oriented towards the north. From there it is easy; export as an .fbx file, bring it to Rhino, fire up Enscape and enjoy the model.
There is the pipeline I was talking about earlier. Metashape is capable of executing predefined sequenced commands. Pressing the start button does all the rest while you enjoy a coffee or a nap.
From the Batch Process menu, add the following functions - Align Photos - Optimize Cameras - Generate Dense Point Cloud - Generate Mesh - Generate Texture.
LARGE SCALE BUILDINGS
This point in particular is what sold photogrammetry to me. Even having a LiDAR Scanner can’t compete with the speed and accessibility photogrammetry provides. In the lecture at Syracuse I speak of scanning the Molson Brewery Building in Montreal. Scanning the whole complex wit LiDAR would have required me to have access to the building, which I didn’t since it was being deconstructed from the inside, and to have easily a full day of moving the scanner around to make sure I get everything. None of this is needed with a drone a total of 60e in was enough to take over 1500 photos to reconstruct the side. Even places Which appeared darker in the photos were reconstructed effortlessly. At larger scales photogrammetry simple saves time .
INSPECTIONS (facade and roof)
It should come as no surprise that having eyes in the sky is a valuable asset. Similarly to my previous point, inspections can be done in the absence of access to a roof or a facade. This makes it easier to inspect buildings at odd times of the day without the necessity of having another person open doors for you. If you’re using a better drone, say a Phantom 4, you can create missions, or predetermined flights, which ensures the constant capture of equal amount of photo during each inspection. Talk about tracking progress over time, wink wink. something worth mentioning is that the model coming out of the scan will automatically have more information than someone’s manually taken photos with their phone. This ensures that small details behind corners, or under metal flashings is always captured and can be discovered dots, if, if not weeks after the inspection.
TELLING STORIES
Let me drive something home: having eyes in the sky IS A VALUABLE ASSET. As architects we build narratives and stories. We don’t simply put materials together and call it architecture. Different perspectives captured from a drone can help you tell a better story of your creation. Not good enough? How about making a short documentary for your clients. Video of their building well positioned in its surrounds only complements our intentions as architects and attest to their success. A drone laying around (hopefully in the air) is an additional tool to tell stories and share your message.
Here is one of my favourite architects talking about the subject better than I can: