Drone Photogrammetry is the science of collecting physical information from 2D photos, often aerial images captured by drones. By combining enough overlapping images of the same features, photogrammetry software can be used to generate photorealistic 3D representations of topographic surfaces.
To understand how drones can be utilized in surveying, let us remind you quickly about drone photogrammetry. It involves taking multiple aerial images of a feature and using them to create digitized high-resolution 2D or 3D models from which accurate measurements can be deduced. This can be completed with specialized mapping software that looks for common features in images and uses them to stitch your photos together in a way that offers an accurate representation of a space. While typically a coordinate point, the exact common feature can vary based on what type of photogrammetry you’re using (more on that later). Depending on the scope of the project, a model made with photogrammetry may require anywhere from a couple hundred to several thousand separate images.
One of the key advantages of photogrammetric aerial photography is that it can be used to create multiple kinds of maps. Depending on the kind of photogrammetry software you have, it is possible to create a variety of outputs, like orthomosaic maps, 3D point cloud models, Digital Surface Models, and more. Other types of mapping, like LiDAR — which uses pulses of light to measure topography — will require a separate payload, however.
Photogrammetry can be broadly divided into two categories:
Metric photogrammetry: This method uses coordinate points on features to visualize an object with near exact measurements. Maps can then be built based on the location of coordinates relative to each other. These coordinates are usually physically set with what is called ground control points.
Interpretive photogrammetry: Rather than specific coordinates, interpretive photogrammetry takes a photograph and adds in topography by looking at indicators like the shapes, shadows, and patterns presented in an image, rather than coordinates.
Each style of photogrammetry can be used for land surveying, depending on the specifics of the job and attention to detail needed. Overall, however, metric photogrammetry is the more precise of the two and is recommended for surveying jobs that need centimeter-level accuracy. Both styles depend on specialized mapping software to stitch together images into a photogrammetric map.
Applications for drone photogrammetry
Construction: Surveying with photogrammetry can reveal information about the land being built on. In addition, aerial modeling with drones can assist in BIM and overall construction project management.
Real estate: Realtors are using drones to make accurate 3D models of homes for sale and offer virtual tours. This technique has taken off because of the COVID-19 pandemic.
Engineering: Engineers can use photogrammetric images to build a 3D model of both buildings and equipment
Energy: Oil and gas companies use drones to monitor the areas around pipelines for environmental changes over time. Land surveying is also commonly implemented in this sector.