3D laser surface scanning and geometric morphometric analysis of craniofacial shape as an index of cerebro-craniofacial morphogenesis: initial application to sexual dimorphism

Three-Dimensional Laser Surface Imaging and Geometric Morphometrics Resolve Frontonasal Dysmorphology in Schizophrenia

“…Facial surfaces were recorded using a portable, handheld Polhemus FastScan laser scanner (Hennessy et al 2002(Hennessy et al , 2005. A typical surface, consisting of ~80,000 points, is shown in Figure 1.…”

“…They were located by the same investigator, blind to diagnostic category, with the aid of conventional vertical and horizontal profiles as described previously (Hennessy et al 2002). Error in location was minimised by landmarking each facial scan four times: twice using the original facial surface and twice with the facial surface mirrored, to avoid systematic asymmetric landmark placement, with the results averaged.…”

“…As an interim approach, we have recently elaborated facial dysmorphology in patients with schizophrenia using limited 3D configurations reconstructed from linear measurements . However, 3D digitisation technologies now allow facial surfaces to be recorded in their entirety and landmark coordinates obtained (Hennessy et al 2002(Hennessy et al , 2005Hammond et al 2004); in a complementary manner, geometric morphometrics, which analyses 3D landmark coordinates directly, provides the basis for relating shape to other biological variables both statistically and visually (Hennessy et al 2005;O'Higgins and Jones 1998;Dryden and Mardia 1998). We have recently applied portable, hand-held 3D laser surface imaging to specify statistically and anatomically the nature of sexual dimorphism in human facial morphogenesis (Hennessy et al 2002) and the relation of facial shape to cognitive function (Hennessy et al 2005(Hennessy et al , 2006.…”

Comparing 3D Descriptors for Local Search of Craniofacial Landmarks

“…2. The 26 landmarks used in this study: en = endocanthion; ex = exocanthion; n = nasion; a = alare; ac = alar crest; nt = nostril top; prn = pronasale; sn = subnasale; ch = cheilion; cph = crista philtrum; li = labiale inferius; ls = labiale superius; sto = stomion; sl = sublabiale; pg = pogonion; t = tragion; oi = otobasion inferius [22].…”

“…The mesh resolution varies between 1.2 and 2.4 mm and, on average, there are 24.2 thousand vertices per mesh. Each scan was annotated with 26 anatomical landmarks, in accordance with definitions in [22] (based on [23]), as indicated in Fig. 2. …”