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Anatomical Terminology
Published in A Stewart Whitley, Charles Sloane, Gail Jefferson, Ken Holmes, Craig Anderson, Clark's Pocket Handbook for Radiographers, 2016
A Stewart Whitley, Charles Sloane, Gail Jefferson, Ken Holmes, Craig Anderson
LandmarksOuter canthus of the eye: the point where the upper and lower eyelids meet laterally.Infra-orbital margin/point: the inferior rim of the orbit, with the point being located at its lowest point.Nasion: the articulation between the nasal and frontal bones.Glabella: a bony prominence found on the frontal bone immediately superior to the nasion.Vertex: the highest point of the skull in the median sagittal plane.External occipital protuberance (inion): a bony prominence found on the occipital bone, usually coincident with the median sagittal plane.External auditory meatus: the opening within the ear that leads into the external auditory canal.LinesInter-orbital (inter-pupillary) line: joins the centre of the two orbits or the centre of the two pupils when the eyes are looking straight forward.Infra-orbital line: joints the two infra-orbital points.Anthropological baseline: passes from the infra-orbital point to the upper border of the external auditory meatus (also known as the Frankfort line).Orbito-meatal baseline (radiographic baseline): extends from the outer canthus of the eye to the centre of the external auditory meatus. This line is angled approximately 10 degrees to the anthropological baseline.
Estimating Level of Engagement from Ocular Landmarks
Published in International Journal of Human–Computer Interaction, 2020
Zeynep Yücel, Serina Koyama, Akito Monden, Mariko Sasakura
Facial landmarks are the set of points marking the locations (or boundaries) of facial components such as eyes, nose, jawline, etc., (Wang et al., 2018). Over the years, numerous landmark estimation methods have been proposed. These methods consider a variety of templates (or maps), which potentially involve a different number of markers (see Figure 2a for a sample template). However, essentially the same facial features are addressed by all templates. In other words, varying templates describe similar facial features, actions, or expressions at varying resolutions. For instance, W. Wu et al. (2018) consider a total of 98 landmarks, whereas Uřičář et al. (2016) consider 68 landmarks and Kasinski et al. (2008) consider 30 landmarks. Since this study focuses on the eyes, we take a closer look at the landmarks describing the eyes (henceforth referred as ocular landmarks) in the aforementioned studies.10 We notice that in all three studies the descriptors of the eyes are constituted by lateral canthus, medial canthus, and palpebral fissure (Neog, 2018). Basically, lateral and medial canthi are represented by a single marker in all approaches, whereas the number of markers over the palpebral fissure is the varying factor. Since the contraction of the palpebral fissure mostly does not involve any lateral movements and the relative positions of the concerning landmarks are expected to be quite stable and dependent, we consider descriptions of the palpebral fissure using different number of markers to have virtually the same effect in representing the state of the eye, provided that the accuracy of landmark estimation is comparable.