What is Photogrammetry?

There are several terms used when discussing the process of creating 3D models from real-world objects, buildings, and landscapes: 3D scanning, 3D digitisation, 3D modelling, structure-from-motion (SfM), image-based modelling, aerial survey, geospatial imaging. When using ground or aerial photography to create a digital model, this is often known as photogrammetry.

The Process

Photos or videos are taken from multiple angles from all sides of the subject. This imaging is then processed through specialized software such as AgiSoft MetaShape or RealityCapture to create an initial point cloud. The software identifies common features throughout the set of images to calculate the 3D shape of the subject. From the resulting point cloud, what’s called a mesh can then be created. This is where the subject starts to take shape, but does not yet look entirely like its real-world counterpart. For that, the software then uses the images to create a texture which gives the subject realistic color.

Post Production

Further work may be required on a photogrammetric model depending on the intended use-case. The model can have quite a dense point cloud which can add to the size of the resulting file. Its mesh can also be made up of a complicated series of triangles which can be hard to manage if further modelling or manipulation work is required. Specialized techniques can be used to reduce the digital size of the mesh and to clean up the mesh.

Model clean-up is typically needed for specific uses such as 3D printing or when being used for public interaction and engagement.

Advantages of Photogrammetry over Techniques like Laser Scanning

Often people think using a laser scanner is the best method for accurate digital capture, but this isn’t necessarily the case. There are a few reasons photogrammetry might be preferable.

• Photo-realistic Texturing – Photogrammetry can capture true-to-life colors and textures, making the 3D model closely resemble the original object.

• Efficient Data Processing – Photogrammetry often produces lower-density point clouds than laser scanning, which can reduce processing times and costs.

• Accessibility – Photogrammetry is more accessible to a broader audience, allowing anyone to contribute by capturing high-quality photos without specialized equipment.

Use Cases for Photogrammetry

There are many use cases for the creation of photogrammetric models and many industries that benefit from these digitisations.

Architecture and Construction
Photogrammetry is used to capture the dimensions and details of buildings and construction sites, helping with site surveys and progress monitoring. It’s particularly valuable for documenting existing structures in renovations or historical preservation

Geographic Information Systems (GIS) and Cartography
In GIS and mapping, photogrammetry helps create detailed maps and terrain models. It’s used in aerial surveys and for mapping large areas like cities or landscapes, where data is needed for urban planning, environmental monitoring, and infrastructure development.

Archaeology and Cultural Heritage
Photogrammetry is a valuable tool in preserving and documenting historical sites and artifacts. By creating detailed 3D models, archaeologists and historians can study, preserve, and display cultural sites and objects. Digital models of historic sites are even being used in restoration projects, such as has been seen after the fire at Notre Dame in Paris.

Film, Gaming, and Virtual Reality
In entertainment, photogrammetry creates realistic 3D models of objects, people, and landscapes for use in movies, video games, and VR experiences. Its ability to capture photo-realistic textures makes it ideal for creating immersive environments and interactive worlds. With the rise in popularity of techniques like Virtual Production in film, television, and ad filming, photogrammetry is becoming more and more key to creating virtual worlds for actors to interact with on production stages.

Environmental and Land Management
Environmental scientists and conservationists use photogrammetry to monitor changes in ecosystems, track erosion, map coastlines, and manage natural resources. Drone-based photogrammetry is particularly useful for surveying areas that are difficult to access on foot.

Civil Engineering and Infrastructure
Civil engineers use photogrammetry to survey sites and monitor infrastructure like roads, bridges, and dams. It’s valuable for inspections, planning, and tracking changes over time, especially in large-scale projects where manual measurements are difficult.

Real Estate and Property Development
Photogrammetry is increasingly used in real estate to create 3D property tours and models of developments, allowing buyers and developers to explore spaces virtually. It’s also used in property planning and visualizations for marketing purposes.

These industries benefit from photogrammetry’s capacity to produce accurate, scalable, and highly visual models, enhancing their analysis, documentation, and planning capabilities.