Photogrammetry — Close-Range Photogrammetry
Close-Range Photogrammetry · Also known as: 3D photogrammetry, structure from motion photogrammetry, SfM photogrammetry, digital photogrammetry
Photogrammetry is a non-contact measurement technique that derives accurate 3D geometry and spatial dimensions from sets of overlapping 2D photographs. In veterinary science it is used to obtain body measurements, wound areas, limb morphology, and anatomical volumes from live animals, carcasses, or skeletal specimens without physical restraint or invasive procedures. Structure-from-Motion (SfM) algorithms have made the method accessible to field and clinic settings using consumer-grade cameras.
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When to use it
Photogrammetry is appropriate when accurate body or anatomical measurements are needed from live animals or specimens and physical contact is difficult, stressful, or unsafe. It is well suited to body condition scoring, wound area tracking, growth monitoring, conformation assessment, and comparative anatomy in veterinary and animal science research. It requires a cooperative or briefly restrained subject, adequate ambient or controlled lighting, and a calibration scale. It is not ideal for internal anatomy (use CT or ultrasound), for very small subjects where macro lens precision is limited, or for moving subjects without high-speed capture protocols.
Strengths & limitations
- Non-contact and non-invasive — measurements are taken from photographs, reducing animal stress and handling risk.
- Produces a permanent, shareable 3D record of the animal or specimen that can be re-measured at any time.
- Applicable in field, farm, and clinic settings with consumer-grade cameras at relatively low cost.
- Captures complex surface geometry (wounds, hooves, joints) with millimetre-level accuracy when properly calibrated.
- Allows extraction of multiple measurement types (linear, area, volume) from a single image set.
- Compatible with standard statistical workflows — outputs are numeric measurements ready for analysis.
- Accuracy depends heavily on image overlap, lighting consistency, and calibration target quality — poor image acquisition degrades reconstruction.
- Moving subjects (breathing, fidgeting) introduce motion blur and mismatched keypoints; some restraint or rapid multi-camera rigs are typically required.
- Reflective, transparent, or uniformly coloured surfaces (e.g., wet fur, eyes, viscera) are difficult to reconstruct without surface treatment.
- Processing a large image set into a dense model is computationally intensive and may take minutes to hours without GPU acceleration.
- Does not capture internal anatomy — photogrammetry is limited to external surfaces visible in the photographs.
Frequently asked
What camera do I need for photogrammetry in a veterinary study?
A consumer-grade DSLR or mirrorless camera with a fixed focal length lens (24–50 mm equivalent) is sufficient for most veterinary applications. The key requirements are sharp, well-exposed images with consistent aperture settings (avoid auto-ISO in low light) and enough overlap between consecutive frames. Smartphone cameras with known focal length can work for preliminary studies but have smaller sensors and less control over exposure.
How accurate is photogrammetry compared to physical tape measurements?
Under controlled conditions with a calibration scale bar, close-range photogrammetry typically achieves accuracies of 1–5 mm for large animal body dimensions, which is comparable to or better than inter-observer variability in manual tape measurements. Accuracy degrades with subject movement, poor lighting, or insufficient image overlap. Validation against physical measurements on a subset of subjects is recommended before adopting the method as a primary outcome.
Can photogrammetry replace computed tomography (CT) for animal measurements?
For external surface measurements — body dimensions, wound areas, external conformation — photogrammetry is a practical and cost-effective alternative. However, it cannot image internal anatomy, tissue density, or subsurface structure, for which CT or MRI remain the appropriate methods. The two techniques are complementary rather than interchangeable.
What free software can I use for veterinary photogrammetry?
Meshroom (AliceVision) is a fully free, open-source SfM pipeline suitable for research use. COLMAP is another widely cited open-source option favoured in academic benchmarks. Commercial packages such as Agisoft Metashape offer more automation and support, with an academic licence at reduced cost. For post-processing point clouds and extracting measurements, CloudCompare is a free and well-documented tool.
Sources
- Falkingham, P. L. (2012). Acquisition of high resolution three-dimensional models using free, open-source, photogrammetric software. Palaeontologia Electronica, 15(1), 1T. link ↗
- Sherrill, L. R., et al. (2019). Use of photogrammetry to measure body dimensions and predict body weight of beef cattle. Translational Animal Science, 3(3), 1467-1478. link ↗
How to cite this page
ScholarGate. (2026, June 3). Close-Range Photogrammetry. ScholarGate. https://scholargate.app/en/veterinary-science/photogrammetry