Hiroyuki Nishimoto

Spherical images capture visual information from all directions in a single frame, making them an essential tool for recording and analyzing landscapes. However, these images differ significantly from conventional photographs taken by cameras or from human visual perception, often resulting in a sense of visual discomfort. To address this issue, this study constructs the theory of a mathematical model for geometrically describing and analyzing landscape representations in spherical images. In particular, the model captures angular deviations that arise from differences in depth to the observed objects as the viewpoint moves. The proposed model is defined by a geometric structure that includes points at infinity in three-dimensional directions, distinguishing it from the conventional Riemann sphere.

Background Detecting life disability is crucial in diagnosing dementia; however, early detection has proven challenging with previous assessment scales. This study focused on an individual's ability to use household appliances as a means of detecting life disability. Objective The objectives of this study are threefold: (1) to compare the ability to use household appliances between the non-dementia and dementia groups, (2) to determine whether the level of life disability based on the ability to use appliances is at the level of diagnosed dementia or non-dementia, and (3) to explore the impact of age and gender on the ability to use appliances. Methods We selected 13 essential household appliances for elderly individuals and proposed an instrumental activities of daily living (IADL) assessment tool to evaluate their usage. Our sample consisted of 98 patients with cognitive impairment, divided into a non-dementia group (N = 34) and a dementia group (N = 64). Most participants in the dementia group had Alzheimer's disease or related conditions. Through multiple logistic regression, the model equation aimed to determine whether a subject's functional disability indicated a potential dementia diagnosis. Results The optimal model equation identified the microwave oven and air conditioner as key factors, achieving an area under the curve (AUC) of 0.78. Additionally, analysis by age and gender enhanced the discriminative power of the results. Conclusions Our proposed scoring system can efficiently determine the degree of life disability by assessing appliance usage, demonstrating comparable discriminatory ability to existing scales.

The images that our eyes perceive are slightly different from the objects. Images in visual space are illusions. However, they are indeed based on optics. In physical space, parallel lines never intersect. In visual space, however, parallel lines intersect at the vanishing point. This is not limited to the human eye; camera lenses produce images similarly. If visual space is spherical, the phenomenon of intersecting parallel lines is no mystery. This paper provides a new geometric model considering the intersection of parallel lines at vanishing points.