Introduction

According to Wikipedia:

Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring and interpreting photographic images and patterns of electromagnetic radiant imagery and other phenomena.

First of all, I like to say that I am not an expert in the field, I’m only a developer trying to do more interesting things with my drone. With that said, to create a 3D model using photogrammetry it’s necessary a bunch of photos that overlap each other.

This is going to be our final result. And here is the code.

The code is pretty simple but a very cool set of libraries and services is necessary to achieve our goal. The steps are as follows:

Flight planning

Every drone comes with a proprietary mobile app and within it intelligent flight modes options. I have a FIMI X8S2, and I am going to use its app here as a reference, but the options are pretty much the same for all drones.

First, you need to choose your target. Here, it will be an old church in my neighborhood.

This is a good youtube video explanning the whole flight planning and capture. It’s in Portuguese, my language by the way, but is possible to activate subtitles in any language.

The idea is to take overlapped photos of the target from different angles. You can use two different flight modes to do that: Orbit or Waypoints. Waypoints is the most used one, but I chose Orbit because it’s more straightforward. In Orbit mode, it's necessary to put the drone at the target's center and choose a radius. The camera must always be pointed at the target.

With the flight plan configured, go to the camera options and choose “Lapse, 2 seconds.” Another important thing to configure it’s the drone velocity during the flight I chose 3 m/s. The combination of velocity and lapse will give us overlapped photos. There are fancy calculations for this, but these are good defaults.

All right, put your drone to flight, fire the photo button, and keep an eye on the camera angle. It should have a good vision of the target. One more thing, the more pictures, the better. I took 241 photos.

Image Processing with OpenDroneMap (ODM)

ODM is an amazing open-source tool; it will take your drone photos and create lots of useful outputs.

The only thing necessary to run ODM is docker. ODM also has good documentation that’s definitely worthy the read. I’m gonna leave the GitHub here. There, you will find more detailed instructions.

So, put your SD card on the computer and take a good look at the images. Delete images that are not pointed to the target. It’s necessary to create two folders for the project, like this: