Active shape model

Active shape models (ASMs) are statistical models of the shape of objects which iteratively deform to fit to an example of the object in a new image, developed by Tim Cootes and Chris Taylor in 1995.

[1] The shapes are constrained by the PDM (point distribution model) Statistical Shape Model to vary only in ways seen in a training set of labelled examples.

The ASM algorithm aims to match the model to a new image.

The ASM works by alternating the following steps: The technique has been widely used to analyse images of faces, mechanical assemblies and medical images (in 2D and 3D).

It is also known as a "Smart Snakes"[1] method, since it is an analog to an active contour model which would respect explicit shape constraints.