Uncertainty Propagation
Definition
The mathematical process of carrying measurement errors through a calculation to estimate the error in the final result. For photogrammetric measurements, it accounts for pixel localisation error, calibration uncertainty, and reference dimension tolerances.
- Purpose
- Estimate error in a final result from input measurement errors
- Photogrammetry inputs
- Pixel localisation error, calibration error, reference tolerance
- Method family
- Analytical (Taylor series) or Monte Carlo simulation
- Output
- A stated confidence interval or error margin, not a single number
Common questions
Why does a photogrammetric measurement need an error estimate at all?+
A single measured value implies false precision. Reporting the propagated uncertainty tells the court how much the estimated height, distance or dimension could realistically vary given the known limits of the imaging and calibration process.
What happens if uncertainty propagation is skipped in a report?+
The measurement can be challenged as unsupported, because the analyst has no basis for stating whether a small difference between two measurements is meaningful or within the expected error of the method.
Related terms
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- Homography
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- Projective Geometry
- The mathematical framework describing how 3D points are mapped to 2D image coordinates through the camera model. Lines remain lines, but distances...
- Structure-from-Motion (SfM)
- A photogrammetric technique in which overlapping images from a drone or camera, processed by software, generate a three-dimensional point cloud and textured...
- Vanishing Point
- The image point where a set of parallel real-world lines converges due to perspective. Identifying vanishing points for multiple sets of parallel...