吉岡 陽介

The impression of streets at night affects crime rates and the out-of-house rate. Therefore, it is important in architectural planning to elucidate the factors that contribute to the sense of safety on streets. Street lighting is one of the effective methods for improving the impression of streets at night. Among the some factors that control the effect of street lighting, the intervals between light and light have a significant impact on the impression of streets. However few studies have examined the relationship between street light intervals and sense of safety on streets.In this study, an experiment using virtual environment technology is conducted to verify the effect of street light intervals on the feeling of safety and discomfort of pedestrians at night. Through the quantitative analysis of the experimental results, the objective of this study is to obtain knowledge on the planning and design of street lighting that reduce discomfort and provides sense of safety.Ten college students participated in the experiment. Since characteristics of personal space may vary by gender, the participants consisted of five males and five females. The participants wore a head-mounted display (Vive Pro Eye / Vive) and were asked to stand upright to a street constructed in infinite virtual space. The light bulbs of a street lights in each condition were placed at a height of 5 m and illuminated the ground downward. The street lights were also placed in a straight line 2 m away to the right of the viewpoint of participants. The initial positions of the approaching unknown pedestrian (virtual avatar) were arranged on the point that 20 m straight ahead of the participant’s viewpoint.First, after the participants stand on the instructed position of virtual street, a start signal was called and the virtual avatar as unknown pedestrian started approaching to at 0.8 m/s. The participants had been asked to press the button of the hand controllers when they felt discomfort that they did not want the avatar to approach any closer. When the button was pressed, the avatar stopped approaching immediately and the distance between participants and avatar was measured and outputted. This measurement was repeated on different conditions of street light intervals to determine how the distance that causes discomfort changed. A total of four experimental conditions were generated by arranging rows of street lights at four different intervals: 12.5, 25, 50, and 100 m. Each condition was presented twice in a random order for each subject. All experimental analyses were performed using the mean of the data derived from the two replicate measurements. The statistical analyses of the experiment data determined a significant difference in the distances at which participants stopped the approaching avatar between conditions with street light intervals of 12.5 m and 100 m. Furthermore, significant trends were detected in the distances between conditions with street light intervals of 12.5 m and 50 m, as well as 25 m and 50 m. These results revealed that the wider the street light intervals, the greater the distance at which the participants feel discomfort that they did not want the avatar to approach any closer. The findings suggest that street light intervals exert an influence on the sense of safety on streets at night. Additionally, despite the absence of statistical significance, it is noteworthy that the distance to stop the avatar was greater magnitude for females than for males.

In our previous study, we have investigated the relationship between the shape of the curved passages and the sense of direction using a head-mounted display (Oculus Quest/Oculus). However, the horizontal visual field of the head-mounted display used in the study was about 90 degrees, whereas the human horizontal visual field is about 200 degrees. Because of this, the results could be different when passing through a curved passage with a wider horizontal visual field. Therefore, in this study, the effect of the horizontal visual field on the accuracy of the sense of direction in the curved passages was investigated.Ten college students participated in the experiment. The subjects were asked to wear a head-mounted display with a visual field of about 180 degrees (StarVR One/ StarVR Corporation) and hold a controller. The subjects also wore soundproof earmuffs to prevent hearing the surrounding sounds. After that, they were asked to walk through some curved passages constructed in a virtual environment.First, a virtual arrow was displayed and arranged at the beginning point of the passage. The subjects were asked to memorize the direction indicated by the virtual arrow (instructed direction). After memorization was completed, the subjects were asked to walk to the end of the passage. When the subjects reach the end of the passage, the entire passage was removed, and only an arrow indicating the traveling direction at the endpoint of the passage appears. After the arrow appeared, the subjects changed the direction of the arrow with the controller to reproduce the instructed direction (reproduced direction). The difference in angle between the “instructed direction” and the “reproduced direction” was used to extract the change in the sense of direction.The passages used in the experiment consisted of curved and straight parts. The width of the passages was 1500 mm, the height was 2500 mm, and the radius of curvature of the curved part was 3500 mm inside and 5000 mm outside. The turning angle of the curved passage was set at six levels in 15 degrees increments, ranging from 15 to 90 degrees (15, 30, 45, 60, 75, and 90 degrees). Furthermore, the subject’s horizontal visual field was restricted to two levels (90 and 180 degrees). A total of twelve conditions were set by combining these two variables. Each condition was presented twice in a random order for each subject.As a result of the experiment, no significant difference was detected in the difference between the “instructed direction” and “reproduced direction” between the condition with the horizontal visual field of 90 degrees and 180 degrees. This result suggested that the accuracy of the sense of direction is not significantly changed even if the horizontal visual field is restricted to 90 degrees. Therefore, the visual field outside of 90 degrees does not seem to affect the accuracy of direction sense in curved passage. For this reason, it is assumed that our previous study results can be applied even when the visual field is wider than 90 degrees.

Controlling human walking speed is an important topic in architectural planning. Understanding the factors that cause changes in walking speed can contribute to the crowd manipulation and the improvement of street attractiveness. Visual information is one of the most important factors for changing the walking speed, and a lot of study has been conducted on it. However, few studies have examined the relationship between walking speed and visual stimuli by color.Therefore, this study conducted an experiment using virtual environment technology to evaluate the effect of the colorfulness of the texture on the sidewall of the pathway on walking speed. The main purpose of this study is to obtain useful knowledge for the design of attractive street through quantitative analysis of the experimental results.Ten university students as the participants were asked to wear a wide view head-mounted display (Star VR one/ Star VR Co. /Horizontal angle of Field of View: 210°) in the experiment. Since the size of the real experimental room was large enough (9,680 mm x 15,600 mm) and the HMD’s position has been fully captured with in the area, the participants could walk around in a virtual environment with their own feet. The participants were asked to walk 6 m along through each of pathways in eight different conditions presented within this virtual environment, and their walking speed was measured. In common setting with each condition, the width of pathway was set at 6m wide and height of sidewalls were also set at 6m on both sides. The entire length of pathway were set at 200 m, so that the end of the pathway was not visible for the participants in walking.The texture of the sidewalls of the pathway consisted of small square tiles joined together. Two levels of the size of the tiles (500mm square or 1000mm square) and two levels of the colorfulness of the tiles (Colored or Non-Colored) were combined to form the different experimental conditions. For each of these four conditions, adding a case in which the participant was asked to gaze at any location and a case in which he was instructed to gaze the point floated 30 m ahead in the travel direction to continue, we made a total of eight conditions. The participants examined these eight conditions in random order.The results of the experiment showed that the average walking speed were significantly higher in the Colored condition than in the Non-colored condition, especially in the case of participants gazing point was not fixed on travel direction. And these significant differences were also found regardless of the tile size level. This result indicates that walking speed was accelerated when walking in the richly "colorfulness" environment than when walking in the less "colorfulness" environment.In addition, in the case of the participant's gaze position was fixed, this significant difference in colorfulness could not be confirmed. This may be due to the ability of peripheral visual field. The peripheral visual field has lower ability to discriminate colors than the central visual field. While the gaze position was fixed to travel direction, the sidewalls were perceived mainly in this peripheral visual field. Therefore, it is considered that the effect of the colorfulness was difficult to appear.

When working in a room, people may choose to work around a window for a sense of openness and recovery of fatigue. However, design around a window for example the size of a window and the distance from the sidewalk may have a negative effect on the mental strain, such as decreased concentration on work.In this study, we examined the effects of design around a window on the mental burden of person working at a desk through a subjective experiment using both a virtual environment technology and an electrodermal activity measurement method. This study is a part of research aimed at obtaining knowledge about design around a window that does not cause mental strain. We arranged floor-to-ceiling height windows and a moving virtual human avatar in the virtual environment and measured the skin potential response (SPR) of the subjects under each condition.A total of eleven students participated in the experiment. The subject wore an electrodermal activity meter and sat in the middle of a quiet experimental room. They also experienced a virtual rectangular room presented via a head-mounted display. The dimensions of the virtual room were set at 3000 mm in width, 2500 mm in depth, and 3000 mm in height. A 3000 mm high window was created on the front wall. We set the subject sat 800 mm away from the window of the virtual room. Human avatars passed outside the window.There are eighteen experimental conditions with those three parameters: three widths of window (1000, 2000, and 3000 mm), three types of avatars (1. walking, 4. jogging, and 5. striding) and two distance levels between the subject and avatar (1000 and 2000 mm). In one continuous trial, three of the eighteen experimental conditions were presented in random order, resulting in three types of avatars appearing at 30-50 seconds intervals while the window width was fixed at a certain level of three. After a 20-second break, the next trial began with the other condition. The order of the window widths and distance level between the subject and avatar was in random order for each subject. During the experiment, the subjects performed a task to type a key in the same direction as an arrow displayed on a monitor.The results showed that the mental strain of the person working at a desk was significantly higher when the window width was 1000 mm in comparison to a window width of 3000 mm. when 1. walking avatar appeared. Compared to the previous experiment in which subjects had no task, the mental strain was significantly reduced in some factors. From these analyses, we find that the narrower the window width, the higher the mental strain on the person working at a desk. Also, it suggests that the mental strain varies depending on existence of a task.These findings may be useful in creating window designs that make it easier to concentrate on tasks.