Photogrammetry

Published 2026-05-26 · UAV Imaging Inc.

Photogrammetry is the science of obtaining precise 3D measurements from 2D photographs. By taking many overlapping images of a subject from different angles, software triangulates common features across the photos and reconstructs the geometry as a 3D point cloud, mesh, or orthorectified map.

Definition

Photogrammetry (from "photo" + "gram" + "metry" — measurement from light recordings) combines optics, projective geometry, and computer vision. The technique pre-dates drones by more than a century — early surveyors used balloon and kite imagery in the 1800s — but commercial drones turned it into a routine tool for everyday measurement.

How drone photogrammetry works

A typical UAV Imaging photogrammetry capture follows five steps:

Flight plan: Software like DJI Pilot 2 or Pix4Dcapture lays out a grid over the area. Forward overlap is set to 80% and side overlap to 70% so every point appears in five or more photos.
Ground control: Surveyed ground control points (GCPs) or RTK / PPK GNSS data anchors the model to real-world coordinates.
Capture: Drone flies the plan autonomously, triggering the shutter at preset intervals. A 50-hectare aggregate yard captures in 30 to 60 minutes.
Processing: Photogrammetry software (Pix4D, Agisoft Metashape, DroneDeploy) runs Structure-from-Motion to estimate camera positions, then dense matching to build a point cloud, then orthomosaic and DSM generation.
Deliverables: Orthomosaic, digital surface model (DSM), 3D point cloud, contour plot, volumes report — packaged in formats clients can open in ArcGIS, AutoCAD, or PDF.

Accuracy

Modern drone photogrammetry routinely delivers:

Horizontal accuracy: 2 to 5 cm with RTK / PPK, 30 to 100 cm without
Vertical accuracy: 3 to 8 cm with RTK / PPK plus GCPs
Volume accuracy on stockpiles: within 1 to 2 percent of ground truth

Accuracy depends on ground sample distance (GSD), overlap, camera quality, lighting, and ground control. UAV Imaging's standard mapping spec targets GSD of 2 cm per pixel.

Photogrammetry vs LiDAR

Both build 3D models. Photogrammetry captures colour and texture from photographs, while LiDAR captures raw range from laser pulses. Photogrammetry wins on cost, colour, and texture richness. LiDAR wins on vegetation penetration and capture in low light. See the glossary or upcoming LiDAR entry for the full breakdown.

Common applications

Stockpile volume measurement
Pit plans and mining surface mapping
Construction progress and earthwork volumes
As-built documentation for civil and survey teams
Heritage and archaeological site recording

Software used by UAV Imaging

Pix4Dmapper / Pix4Dmatic: primary processing engine for mapping + volume work
DroneDeploy: field-ready quick orthomosaics + progress reports
Agisoft Metashape: high-density point clouds for engineering deliverables

Frequently Asked Questions

What is photogrammetry in simple terms?

It is the technique of measuring 3D shapes from 2D photos. By taking many overlapping pictures from different positions, software figures out the 3D position of every common point and rebuilds the scene.

How accurate is drone photogrammetry?

With RTK or PPK GNSS and ground control points, expect 2 to 5 cm horizontal and 3 to 8 cm vertical. Volume accuracy on stockpiles is typically within 1 to 2 percent of ground truth.

Is photogrammetry the same as 3D mapping?

Photogrammetry is one of two main methods (the other is LiDAR) used to produce 3D maps. The output of a photogrammetry flight is a 3D map. So all photogrammetry produces 3D mapping, but not all 3D mapping uses photogrammetry.

How long does processing take?

A 50-hectare flight typically processes overnight on a workstation, or in 1 to 3 hours on cloud services like Pix4Dcloud or DroneDeploy.

What weather conditions are needed?

Diffuse overcast light is ideal — flat shadows give the matching algorithm consistent features. Hard sun creates strong shadow edges that confuse the algorithm. Wind under 35 km/h is acceptable for most aircraft.

Need a quote? Call 587-532-9000 or contact us online for commercial drone services across Alberta.

Glossary