A Practical Tool for Ambient Illumination Comparisons at Dusk/Dawn

Abstract

Nighttime visibility is an important consideration in collision reconstruction and personal injury investigation. Decreased contrast in low ambient lighting conditions can greatly affect human perception and response. Because ambient lighting levels change rapidly at dawn and dusk, forensic investigators must have an accurate knowledge of the time of day and the cloud conditions at the time of the incident before initiating a nighttime visibility assessment. Previously, human factors experts attempting re-enactments at dawn or dusk have had to wait for sky conditions that match those at the time of the incident, making the investigation of those cases extremely difficult, if not unfeasible. In this study, an ambient illumination equivalency tool has been developed based on a database of time-lapse light meter readings collected by the authors. This new tool can be used to facilitate nighttime visibility assessments on any day by providing a time adjustment factor to account for the changes in ambient illuminance due to differences in the cloud conditions between the day of the incident and the day of the re-enactment.

Should We Re-think Regulations and Standards for Lighting at Workplaces? A Practice Review on Existing Lighting Recommendations

“…With the increased time spent in buildings, the length of time during which people are exposed to high amounts of daylight decreases. Although, lighting standards for workplaces ensure that we can see well, specifications for artificial lighting correspond to twilight conditions outdoors ( 7 ). 500 lx of artificial light indoors corresponds to ~0.5% of the light on a cloudless day.…”

Reconstruction of the Visual Environment of a Police Pursuit Incident from Several Points of View

“…The time was 30 minutes after the end of astronomical twilight, when the sun was a full 24 degrees below the horizon; distance visibility was excellent (over ten miles) but there was low cloud cover reflecting light from a small, nearby urban area. A true horizon was not visible, but a near approximation could be inferred from the ambient lighting conditions (Lam, Gani, Mawson, Young & Potma, 2016). Traffic density was light, and also equivalent to conditions at the time of the police interception.…”

Nighttime Photography & Videography: Techniques & Tips

“…Investigation of nighttime motor vehicle collisions represents one of the most challenging aspects of collision reconstruction (Lam et al, 2016). Nighttime collisions with motorcycles, pedestrians, cyclists, skateboarders, or wildlife will often require the investigator to assess the visibility of the struck object from the driver perspective at the time of the collision (Young et al, 2009).…”

“…Nighttime collisions account for a disproportionately high number of collisions (Owens et al, 1996;NHTSA, 2009;Transport Canada, 2011. In order for a collision investigator to assess driver avoidance opportunities for a nighttime collision, there must be reliable evidence regarding the lighting conditions at the time (Lam et al, 2016). For dawn or dusk collisions, there must also be reliable evidence regarding the basic weather conditions, since the weather conditions affect the ambient illumination (Darula and Kittler, 2001;Lam et al, 2016).…”