Photogrammetry

Photogrammetry is the science of extracting measurements and shape from photographs. A building, facade or object is captured in many overlapping photos from different positions; software matches common points across the images, works out where each camera stood and calculates the 3D position of those points. The result can be a point cloud, a textured mesh or a scaled orthophoto.

Photogrammetry in architecture

Measured surveys, heritage documentation and terrain modeling are the best-known uses. It can be done from the ground with an ordinary camera, while roofs and large sites are often shot from drones. The equipment is more accessible than a laser scanner and it captures true color by nature. Accuracy, however, depends heavily on photo quality and on control points.

Getting good results

• Leave generous overlap between photos and cover the subject from every side.
• Soft, overcast light works better than hard shadows.
• Glass, mirrors, shiny metal and plain featureless walls make matching difficult.
• For true scale you need a known distance or surveyed control points.

In visualization, photogrammetry is a strong way to produce realistic textures and context models; scanned stone, bark and soil add a natural richness to a render. For its role in documenting historic buildings, see conservation and restoration of architectural heritage.