Photogrammetry
3D Surface Modelling and Measurement from Photography
Photogrammetry reconstructs three-dimensional geometry from overlapping photographs by identifying common features across images and triangulating their spatial positions. The resulting 3D model captures surface geometry and visual texture with accuracy sufficient for many structural investigation applications, at a fraction of the cost of LiDAR scanning when full volumetric point cloud density is not required.
For structural investigation, photogrammetry provides measurable 3D surface models from which crack widths, displacements, spalling extent, and geometric dimensions can be extracted. When combined with drone imagery, photogrammetry produces detailed 3D models of building facades, roofs, and other access-restricted surfaces that can be measured and analysed remotely after the field survey is complete.
TRSC uses photogrammetry for crack mapping and defect documentation where traditional 2D photography lacks measurement capability. A photogrammetric model allows engineers to measure crack widths, crack lengths, spalling areas, and displacement magnitudes directly from the 3D model, producing quantified defect records that can be compared with subsequent surveys to track deterioration progression over time.
Photogrammetry complements rather than replaces LiDAR scanning. LiDAR provides higher geometric accuracy and captures geometry regardless of surface texture, while photogrammetry provides superior visual texture (true-colour surface mapping) and works with standard cameras without specialist scanning equipment. TRSC selects the appropriate technology based on the accuracy requirements, surface characteristics, and investigation objectives.
Speak with an RPEQ-qualified structural engineer about deploying this technology on your asset.
Applications
Facade Documentation
Producing measured 3D models of building facades from drone or ground-based photography, enabling remote measurement and defect quantification.
Crack Mapping & Measurement
Creating orthomosaic images and 3D models from which crack widths, lengths, and patterns can be measured with millimetre accuracy.
Defect Quantification
Measuring spalling extent, displacement, and deterioration area from 3D photogrammetric models, replacing manual measurement with repeatable digital measurement.
Change Detection
Comparing photogrammetric models from different survey dates to detect and quantify changes in surface condition, crack growth, spalling progression, and displacement.
Heritage Recording
Producing textured 3D models of heritage structures for conservation documentation, planning submissions, and public interpretation.
Scope Estimation
Measuring surface areas, volumes, and quantities from photogrammetric models for remediation scope estimation and tender documentation.
Frequently Asked Questions
How does photogrammetry compare to LiDAR?
Photogrammetry produces 3D models from photographs and is best for surface texture capture and visual documentation. LiDAR produces point clouds from laser pulses and provides higher geometric accuracy regardless of lighting or surface texture. For structural investigation, LiDAR is preferred when sub-millimetre accuracy is required; photogrammetry is preferred when visual texture and cost-effectiveness are priorities. TRSC uses both technologies depending on the investigation objective.
Can photogrammetry work indoors?
Yes, provided there is adequate lighting and surface texture for feature matching. Uniform, textureless surfaces (smooth painted walls) may not produce reliable results. TRSC uses supplementary lighting and surface targets where necessary to ensure reliable photogrammetric reconstruction in interior environments.
What accuracy can photogrammetry achieve?
With ground control points and appropriate photography, photogrammetry achieves ±2–5mm accuracy for structural measurement purposes. This is sufficient for crack mapping, defect quantification, and facade documentation, but not for deformation measurement where sub-millimetre accuracy is required. For high-accuracy deformation analysis, TRSC uses LiDAR scanning.
Deploy PG on your asset
Every investigation begins with a direct conversation with an RPEQ-qualified structural engineer. No sales intermediary, contact TRSC to discuss whether photogrammetry is appropriate for your structural question.