Procrustes Superimposition
Definition
The statistical procedure in geometric morphometrics that removes non-shape variation (translation, rotation, scale) from a set of landmark coordinates, leaving only shape differences for analysis. Named after the mythological figure by analogy with standardisation.
- What it removes
- Size, position, rotation, and orientation variation
- What it preserves
- Shape differences only
- Method type
- Geometric morphometrics statistical procedure
- Output
- Coordinates in common Procrustes shape space where distance measures shape difference
Common questions
What does Procrustes superimposition actually do?+
It's a statistical technique that takes landmark coordinates from multiple specimens and removes all the non-shape differences between them. Specifically, it strips out size, position, and rotation variation so that what's left is pure shape difference. This lets you compare shapes fairly without the noise of how big something is or which way it's oriented.
Does Procrustes superimposition have anything to do with the Greek myth?+
Only the name. The procedure uses the myth as an analogy for standardization, but there's no deeper connection to the mythological story. It's just a memorable label for the technique of fitting everything into a common reference frame.
When would a forensic analyst use Procrustes superimposition?+
It's a core step in geometric morphometrics work, especially in modern 3D scanning analysis. When you have landmark coordinates from skeletal elements or other structures, you apply Procrustes superimposition to align them all in the same mathematical space so you can measure real shape differences that might matter for identification, estimation, or comparison.
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