Search Results (3)

Accurate pupil localization is crucial for the eye-tracking technology used in monitoring driver fatigue. However, factors such as poor road conditions may result in blurred eye images being captured by eye-tracking devices, affecting the accuracy of pupil localization. To address the above problems, we propose a real-time pupil localization algorithm for blurred images based on double constraints. The algorithm is divided into three stages: extracting the rough pupil area based on grayscale constraints, refining the pupil region based on geometric constraints, and determining the pupil center according to geometric moments. First, the rough pupil area is adaptively extracted from the input image based on grayscale constraints. Then, the designed pupil shape index is used to refine the pupil area based on geometric constraints. Finally, the geometric moments are calculated to quickly locate the pupil center. The experimental results demonstrate that the algorithm exhibits superior localization performance in both blurred and clear images, with a localization error within 6 pixels, an accuracy exceeding 97%, and real-time performance of up to 85 fps. The proposed algorithm provides an efficient and precise solution for pupil localization, demonstrating practical applicability in the monitoring of real-world driver fatigue. Full article

Distinguished from conventional lighting, the LED vertical surface light source (VSLS) is directly exposed to human view, and the effects of which form it takes on visual perception are non-negligible. In the current discomfort glare evaluation system, the solid angle and the position index, which represent the relative relation between the glaring light source and human visual field, are not completely applicable for large-area VSLS, and hence are awaiting supplementation and modification. In this study, a physical experimental setup was established to conduct an evaluation experiment on discomfort glare, employing an LED display and white translucent frosted film to simulate vertical surface light sources (VSLS). The experiments were arranged with 21 VSLS shapes (comprising 3 areas and 7 length-to-width ratios) and 11 mounting positions. Subjective ratings and four eye-movement data parameters—namely, the change rate of pupil diameter (CRPD), mean saccadic amplitude (SA), blinking frequency (BF), and saccadic speed (SS)—were collected from 24 participants under each working condition using the Boyce Evaluation Scale and eye tracking techniques. The main results of this study are the following: (a) CRPD is the most appropriate eye-movement index for characterizing VSLS glare perception; (b) The area of the VSLS is the primary shape element influencing discomfort glare. Furthermore, with the same surface area, the lateral view angle (LaVA) and the longitudinal view angle (LoVA) perceived by the human eye also impact glare perception; (c) A functional equation between the VSLS area, LaVA, and LoVA to the borderline luminance between comfort and discomfort (BCD luminance) is fitted; (d) Based on the eccentric angle and the azimuthal angle, a modified position index P’ is proposed to represent the relative position of the VSLS in the visual field, and the ratio function of BCD luminance of the VSLS at non-central positions and the central position is fitted. Full article

Childhood obesity is a public health problem with multiple effects on children’s life. Promoting Active School Travel (AST) could provide an inclusive opportunity for physical activity and shape healthy behaviours. Data for this cross-sectional study were drawn from questionnaires carried out in five primary schools located in Newcastle upon Tyne, UK, in neighbourhoods chosen for their variability in IMD (index of multiple deprivation) and spatial structure of street networks (measured through space syntax measure of integration). A randomly selected and heterogenic sample of 145 pupils (aged 9–10) completed an open-ended questionnaire to state what they like and dislike about their journey to school. Thematic analysis identified four typologies (environmental context, emotions, social influences and trip factors) based on the Theoretical Domains Framework (TDF) and specific themes and sub-themes underlying children’s affective experiences of their journeys to school. This study is the first known to authors to attempt to adapt the Capability, Opportunity and Motivation Behaviour (COM-B) model into AST and children’s experiences and associated behavioural domains with design aspects. Such an insight into children’s attitudes could inform urban planners and designers about how to apply more effective behaviour change interventions, targeting an AST increase among children. Full article