Objective: Reflection on visual problems in nursing homes. Data Sources: Eye examinations, documented visual problems and illuminance levels. Study design: The optometric examinations and recorded visual problems were combined with illuminance data. Data collection: In seven nursing homes, 259 residents underwent an optometric examination. Their client records were analyzed for information rega...

Generating soft shadows in real-time is difficult. Exact methods (such as ray tracing, and multiple light source simulation) are too slow, while approximate methods often over-estimate the umbra regions. In this paper, we introduce a new algorithm based on the shadow map method to quickly and accurately render soft shadows produced by a light source. Our method builds inner and outer translucen...

In this paper, a power-controllable light emitting diode (LED) control system is proposed for plant cultivation. The proposed LED system measures environmental data, such as the distance between the plant and LED system using an infrared sensor and the ambient illuminance based on an illuminance sensor. Then, it converts the illuminance to the photosynthetic photon flux density (PPFD) for plant...

The earth-atmosphere stray light can lower contrast ratio and SNR of spatial optical remote sensors, or even fail the system at certain conditions. Errors in the calculation of the stray light illuminance based on point source are very large, for the satellite’s altitude is only several hundred kilometers and far less than the radius of the earth. This paper proposed a stray light illuminance c...

BACKGROUND Daylight availability data are essential for designing effectively day lighted buildings. In respect to no available daylight availability data in Iran, illuminance data on the south facing vertical surfaces were estimated using a proper method. METHODS An illuminance measuring set was designed for measuring vertical illuminances for standard times over 15 days at one hour interval...

We measured r.m.s. contrast sensitivity as a function of retinal illuminance at various spatial frequencies within 3-37 deg of eccentricity in the nasal visual field. In dim light contrast sensitivity increased in proportion to the square root of retinal illuminance obeying the DeVries-Rose law but in bright light contrast sensitivity was independent of luminance following Weber's law. Critical...

An experiment in a mock-up office space gave occupants control over dimmable lighting circuits after a day working under pseudo-random lighting conditions. Data analysis indicated that the lighting experienced during the day influenced the changes in lighting made at the end of the day. Occupants chose to reduce screen glare if any existed. Even after allowing for the effect of glare, desktop i...

A theory is presented to analyze images of anisotropic fine-scale surfaces. We investigate the estimates of illuminance flow by using structure tensors. For anisotropic surfaces, both the gradient-based and the Hessian-based tensors will yield deviations from the true illumination orientation. Our theory predicts this deviation. To show the use of this theory, an algorithm is derived that uses ...

BACKGROUND Alcohol-related driving accidents and fatalities occur most frequently at nighttime and at dawn, that is, a mesopic lighting condition in which visual processing depends on both rod and cone photoreceptors. The temporal functions of the rod and cone pathways are critical for driving in this lighting condition. However, how alcohol influences the temporal functions in the rod and cone...