What is photogrammetry?
Photogrammetry is a surveying method that uses photographs to determine the geometry and spatial position of objects and surfaces. When images are captured from the air using a professional drone, large areas can be surveyed efficiently while generating detailed and measurable spatial data.
Modern photogrammetric workflows can transform hundreds or even thousands of aerial photographs into orthophotos, point clouds, 3D models and digital terrain or surface models.
The result is far more than a collection of aerial photographs: it is a structured digital representation of the surveyed area.
How does a drone survey work?
A professional drone survey generally consists of several important steps.
1. Defining the survey area
The first step is to determine the exact area and purpose of the survey. The required accuracy and final deliverables also need to be considered at this stage.
2. Flight planning
The flight path and image acquisition parameters are planned according to the size and characteristics of the area. Appropriate overlap between photographs is essential for successful photogrammetric processing.
3. Aerial image acquisition
The drone captures a series of overlapping photographs while following the planned flight path. Depending on the project, additional surveying equipment or ground control points may also be used to improve accuracy and georeferencing.
4. Data processing
The collected images are processed using specialized photogrammetric software. The software identifies common features in overlapping photographs and uses them to reconstruct the geometry of the surveyed environment.
This process can produce several different types of digital outputs.
What can be created from aerial images?
Orthophoto
An orthophoto is a geometrically corrected aerial image in which distortions caused by terrain and perspective have been corrected. It can therefore be used as a measurable map-like representation of the surveyed area.
Orthophotos are useful for documentation, planning, site monitoring and spatial analysis.
3D point cloud
Photogrammetric processing can generate a dense 3D point cloud containing a large number of spatially positioned points.
The point cloud can be used for measurements, visualization, analysis and further 3D processing.
3D model
The collected data can also be transformed into a detailed 3D model of buildings, terrain or other objects.
This can provide an easily understandable digital representation of the surveyed environment and can be particularly useful for planning and documentation.
Digital terrain and surface models
Photogrammetric data can be used to generate digital models representing terrain and surface features. These models can support terrain analysis, earthwork calculations, construction planning and other engineering applications.
Where can drone surveying be useful?
Construction sites
Drone surveys can provide an up-to-date overview of large construction sites. Regular surveys can help document progress and create comparable datasets throughout the project.
Large areas and difficult-to-access locations
Surveying large or hard-to-reach areas from the ground can be time-consuming and sometimes difficult. A drone can collect a significant amount of spatial information efficiently while reducing the need for physical access to every part of the site.
Buildings and roofs
Aerial imagery can be particularly useful for surveying roofs, façades and other areas that are difficult to inspect from ground level.
The resulting data can support condition documentation, renovation planning and further analysis.
Terrain analysis
Drone photogrammetry can provide detailed information about terrain geometry, making it useful for earthworks, infrastructure projects, construction planning and site analysis.
Investment and project preparation
Before starting a larger construction or development project, up-to-date spatial information can help establish a reliable basis for planning and decision-making.
What are the advantages of drone surveying?
One of the main advantages of drone-based data collection is efficiency.
Aerial imagery makes it possible to survey relatively large areas in a short amount of time while collecting a large volume of spatial information. The same dataset can then be processed into different outputs depending on the project’s requirements.
Another important advantage is repeatability. The same area can be surveyed at different stages of a project, allowing changes to be documented and compared over time.
Drone surveying and traditional surveying methods
Drone surveying does not necessarily replace traditional ground-based surveying methods.
In many professional projects, the two approaches complement each other.
Ground surveying can provide highly accurate control measurements and detailed information at specific locations, while drone photogrammetry can efficiently capture large areas and provide a comprehensive visual and spatial overview.
Combining these methods can therefore provide a more complete dataset than relying on either technique alone.
Accuracy depends on the quality of the data
Professional drone surveying is not simply a matter of taking photographs from the air.
The quality and accuracy of the final results depend on several factors, including:
- flight planning,
- image quality,
- image overlap,
- ground control,
- positioning,
- weather and lighting conditions,
- and the quality of the photogrammetric processing.
For this reason, professional planning and data processing are essential when the resulting models and measurements are intended for engineering, surveying or construction purposes.
The real value is in the digital data
One of the biggest advantages of photogrammetry is that a single survey can produce multiple types of useful digital data.
The same aerial survey may provide an orthophoto for visual documentation, a point cloud for measurements, a 3D model for visualization and a terrain model for engineering analysis.
This makes drone photogrammetry a flexible solution for projects where both visual information and precise spatial data are required.
Conclusion
Drone surveying and photogrammetry provide an efficient way to capture detailed information about large areas, buildings and terrain.
By processing aerial photographs, it is possible to create orthophotos, point clouds, 3D models and digital terrain or surface models that can support planning, construction, documentation and analysis.
The real advantage is not simply the aerial photograph itself, but the structured spatial data created from it.
When properly planned, captured and processed, drone photogrammetry can provide a valuable digital foundation for a wide range of surveying, engineering and construction projects.