Performance of semi and fully automated approaches for registration of 3D surface coordinates in geometric morphometric studies

GONZALEZ PN, BARBEITO - ANDRÉS J, D'ADDONA L, BERNAL V, PEREZ SI

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2016 vol. 160 p. 169 - 178

0002-9483

The aim of this paper is twofold: a) to assess theperformance of automatic techniques for sampling  point coordinates on 3Dsurfaces, and b) to evaluate the effect of sliding surface points by bending energy and minimum Procrustes distance. Three datasets comprising morphological structures with disparate levels of complexity and intra-sample variation: mouse molars, mouse brains and primate endocasts. Different configurations of 3D coordinates on curves and surfaces were digitized from MRI images and CT scans using semi and fully automated procedures. Shape variables were obtained by Generalized Procrustes Superpositions before and after sliding the pseudolandmarks. Multivariate analyses were used to summarize and compare shape variation. For the primate endocast thesemi-automatic and automatic strategies yield to similar ordinations among the species being compared. At the other extreme, the semi-automatic strategy better discriminates molar shapes between mouse groups. Surface pseudolandmarks digitized automatically display more meaningful distances among specimens in the shape space when the points are slid. The analysis of surface semilandmarks obtained automatically from 3D models is a promising approach, although it should be used with some caution in very complex structures. Infact, the automatic and semi-automatic approaches should be seen ascomplementary since the second performs better for assessing shape variation inlocalized traits that have been previously selected, while automatic methods are suitable in studies aimed at comparing overall variation in shape and when there is no previous information about which anatomical regions might be more variable.