What is photogrammetry used for? Industries and applications

Photogrammetry is used wherever something has to be measured and cannot conveniently be touched: a quarry face, a crop, a crash scene, a cathedral ceiling, an actor’s face. The method is the same in every case, photographs with overlap turned into a measured model; what changes is the scale, the accuracy needed and what is done with the model afterwards. This page goes industry by industry, saying what each measures with it and why a camera won the job.

The industries, at a glance

• Surveying and mappingTopographic surveys, contours, orthomosaics, elevation models and base maps, from a field to a county. The industry photogrammetry was invented for.centimetres · drones and aircraft
• ConstructionPre-design survey, earthworks volumes, progress against the programme, as-built records, and the photographs and issues that go with each. A flight a month.centimetres · drones
• Mining and quarriesStockpile volumes, pit and face surveys, haul road grades, blast reconciliation, tailings monitoring. Where surveyors cannot safely walk.1–3% on volumes · drones
• AgricultureCrop height and vigour, plant counts, drainage and field levelling, variable-rate maps from multispectral cameras flown with the ordinary one.decimetres · drones
• ForestryCanopy height models, stand volumes, tree counts, storm and fire damage, with LiDAR beside it for the ground under the trees.decimetres · drones and aircraft
• Archaeology and heritageExcavations recorded layer by layer, buildings and monuments modelled to the millimetre, inscriptions read from raking light. The record that survives the dig.millimetres · cameras, drones
• Forensics and accidentsCrash and crime scenes reconstructed as measured models before the road reopens: distances, sight lines, skid marks, bullet paths, shown in court.centimetres · cameras, drones
• InspectionBridges, towers, roofs, façades, tanks and solar farms photographed close and modelled, so a crack can be measured and found again next year.millimetres to centimetres · drones
• Insurance and real estateRoof measurements for a quote or a claim, storm damage assessed from the air, properties modelled for listings and for the record before and after.centimetres · drones, phones
• Film, games and museumsActors, props, sets and artefacts captured as textured 3D models: digital doubles, game assets, virtual museums, products for the web.sub-millimetre · camera rigs
• Geology and the environmentLandslides, cliffs, glaciers, dunes and riverbanks measured between dates to see what moved and by how much. Erosion as a number.centimetres · drones
• Underwater and the coastReefs, wrecks and pipelines modelled from diver or ROV photographs; beaches and dunes from the air; shallow beds from the surface where the water is clear.centimetres · underwater cameras

Surveying, construction, mining

These three measure ground, and ground is what photogrammetry does best: open, textured, still, and seen from above. A surveyor’s drone replaces a day of walking with a half-hour flight and brings back not a few hundred points but a point for every pixel. The construction site flies monthly and reads earthworks volumes, grades and progress off the model; the quarry flies the same way and reads stockpile volumes to a few percent, which is the single most common thing anybody does with a drone survey.

Surveying

Topographic survey to a stated accuracy class, contours, the orthomosaic as the base map, cross-sections along an alignment. Control and check points on every job.

Construction

Volumes of cut and fill against the design surface, progress by area and element, as-built records at handover, photographs and issues pinned to the map. A flight a month, more during earthworks.

Mining and quarries

Stockpile volumes, pit surveys for reserves and reconciliation, face profiles, haul road grades, tailings dam monitoring. Flown where nobody should walk.

Clarity is built for these three: the progress page shows the monthly rhythm, and the stockpile guide the measurement. Where the ground is wooded, the LiDAR comparison says when to fly a laser instead.

Agriculture, forestry, environment

Over fields and forests the questions change from “where is the ground” to “how is the crop”, and the camera changes with them. A multispectral camera, flown beside the ordinary one, records the bands that plant stress shows in before the eye sees it; the photogrammetry on the ordinary camera gives the map those bands are laid on, plus crop height from the surface model, plant counts from the orthomosaic and drainage from the terrain. In forestry the surface model is the canopy, its height above the ground is the stand, and LiDAR supplies the ground the camera cannot see.

Archaeology, heritage, forensics

Here the model is the record, and the thing it records is about to change or disappear: an excavation layer that will be dug through tomorrow, a monument that is weathering, a crash scene that the road has to be reopened over. Archaeologists photograph each layer before removing it and keep a measured model of every stage; conservators model a façade to the millimetre so the next survey can be subtracted from it; investigators photograph a scene from the ground and from a drone and reconstruct it afterwards, measuring distances and sight lines that nobody thought to tape at the time.

Excavations

Every context modelled before it is removed; the whole dig reassembled afterwards in one coordinate system. A phone and a scale bar is enough for a trench.

Buildings and monuments

Façades, interiors and statuary at millimetre resolution; raking-light photographs that bring out worn inscriptions. Repeated to measure decay.

Accident and crime scenes

Models made from photographs taken by officers and by a drone, before the scene is cleared, with scale bars and control. Accepted in court when the capture and its accuracy are documented.

Museums

Artefacts modelled for study, replication and display; whole collections captured on turntables and published online.

Inspection, insurance, real estate

An asset owner wants to know what state something is in and whether it has changed. A drone flown close to a bridge, a tower, a tank or a roof brings back photographs an inspector can examine without a rope or a platform, and a model those photographs can be measured and located on: a crack’s length and exact position, a panel’s pitch, a roof’s area for a quote to the square metre. Insurers fly after storms and settle claims from the orthomosaic; estate agents model a property; owners keep a dated record of what was there before the works.

Film, games, museums, products

The industries that want the model for its own sake, and want it to look right rather than to measure right. A rig of a hundred cameras fires at once and captures an actor’s face in a fiftieth of a second; a prop or a costume goes on a turntable; a location is flown and walked and comes back as a set that can be lit from any angle. The method is the same close-range photogrammetry as the archaeologist uses, with the emphasis moved from control to texture: even light, cross-polarised to kill reflections, and as many pixels on the subject as the lenses allow.

The 3D scanning comparison draws the line between the two.

Geology, hydrology, the sea

Scientists use photogrammetry to measure change: the same cliff, glacier, dune or riverbank flown twice and subtracted, so erosion, retreat and deposition become volumes with dates on them. Meteorologists measured cloud heights from paired photographs long before drones existed, and the technique still finds the base and top of a storm. Under water, divers and remotely operated vehicles photograph reefs, wrecks and pipelines, and the same software builds models from the pictures, within the limits that light and turbidity set.

What each one needs from the survey

The industries differ less in the method than in what they ask of it. The table is the shorthand: the accuracy the job needs, the product it reads, and the thing it most often goes wrong on.

Whatever the industry, the first three are the ones Clarity is made for. The stockpile, cut and fill and contours pages go through the jobs, and the equipment page says what to buy for it.