It’s all good and well to decide you want to try something completely new (like photogrammetry in our case) as a core part of your game, but you have to then start with doing some tests. We looked online, did some research and read a lot of valuable methods that are used in the field already. For our case we have a very concrete and consistent thing that we want to scan though: cliffs, boulders and structures. This gave us a very clear goal and limitations. Time to test out the methods in practice!
First time we went out with our phones and took a bunch of pictures of some boulders. The results were surprisingly good, which gave us a lot of hope that we actually made a good choice.
Based on those first tests we were convinced that we would be able to use photogrammetry for creating the models, but if we want to scan a whole cliff it would take quite a while to climb every part of it with a phone in our hand. Therefore we decided that it would be a good idea to buy a drone and get the licenses to be able to legally and safely fly it.
Our drone of choice is the DJI Air 2S. It has a great sensor, really good image stabilization with a gimbal, it’s compact and light, and comes with actually decent software to control it. So Guido took it on himself to become our professional drone pilot. He actually didn’t have too many issues with getting the licenses. Honestly the hardest part was figuring out which licenses are required to have.
Now with the drone at hand or rather in the air we started looking into a good methodology for collecting the photos needed. We found an old brick factory close to our office with enough space around it so we can safely try out some things. We started by moving, shooting a photo, moving, shooting a photo, etc. It proved very inefficient! The drone needs to be fully stationary, else the photo gets blurred and the 3D result will only be worsened by that picture. And it is intensely time / energy consuming.
Next we tried shooting videos, because maybe the quality would already be good enough. We extracted the frames from the video at an interval. Better! And most importantly: easier! This allows us to move, keep the drone still for a moment, move, still, etc. Especially for the scale that we are capturing at having a more efficient process would save us potentially hours or even days of time. This would then balance out the lower quality photos by having a more consistent lighting on the location.
With a methodology tested and approved for quality we decided that it was time for the real deal. In the next part we will be talking about how we decided where to go, how to prepare for a photo scan of a cliff and how we applied our methodology at scale.