The apparent color of an object within a scene depends on the spectrum of the light illuminating the object. However, recording an object's color independent of the illuminant spectrum is important in many machine vision applications. In this paper the performance of a blackbody-model-based color constancy algorithm that requires four sensors with different spectral responses is investigated un...

COLOR-BASED MODELS FOR OUTDOOR MACHINE VISION FEBRUARY, 2002 SHASHI D. BULUSWAR, B.A., GOSHEN COLLEGE M.S., UNIVERSITY OF MASSACHUSETTS AMHERST Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Allen R. Hanson This study develops models for illumination and surface reflectance for use in outdoor color vision, and in particular for predicting the color of surfaces under outdoor c...

Linear models have already been proved accurate enough to recover spectral functions. We have resorted to such linear models to recover spectral daylight with the response of no more than a few real sensors. We performed an exhaustive search to obtain the best set of Gaussian sensors with a combination of optimum spectral position and bandwidth. We also examined to what extent the accuracy of d...

BACKGROUND In bright light, mammals use a distinct photopigment (melanopsin) to measure irradiance for centrally mediated responses such as circadian entrainment. We aimed to determine whether the information generated by melanopsin is also used by the visual system as a signal for light adaptation. To this end, we compared retinal and thalamic responses to a range of artificial and natural vis...

This study investigates the daylighting and thermal performance of open-plan office buildings with two scenarios of daylight louvers – fixed and motorized ones. Both types are for facade window applications. They redirect transmitted daylight to eliminate glare on occupants and increase daylight levels deeper in the interior space, but have significantly different daylight transmitting characte...

BACKGROUND Daylight saving time affects millions of people annually but its impacts are still widely unknown. Sleep deprivation and the change of circadian rhythm can trigger mental illness and cause higher accident rates. Transitions into and out of daylight saving time changes the circadian rhythm and may cause sleep deprivation. Thus it seems plausible that the prevalence of accidents and/or...

This paper presents a fast algorithm for daylight simulation and analysis of complex architectural environments that considers both direct sunlight and diffuse daylight. Shadow determination is performed using a combination of parallel projection and ray tracing techniques. Parallel projection provides execution times that are linear with respect to the number of polygonal objects in the enviro...

The sensitivity of the circadian pacemaker of the field mouse Mus booduga to diffuse daylight pulses of 15 min duration and 1000 lux intensity was measured in a series of experiments and a phase response curve (PRC) constructed. The PRC evoked was of type-I with significant quantitative differences compared to the PRCs constructed for other light stimuli (fluorescent and incandescent light sour...

Figures for the United States indicate approximately 40,000 road fatalities per year. Per 100,000 miles driven, the nighttime accident rate on unlighted highways is roughly three times that during daylight hours. While this is partly alcohol and fatigue related, the major factor is believed to be the reduced visual performance of the driver under night conditions. Statistics for other countries...

Most designers would agree that natural light is essential to the experience of any great work of architecture, but as a professional discipline, we lack consensus on which characteristics of daylight quantify or qualify the visual performance of a space. Perceptual qualities such as brightness, contrast, and temporal variability influence our experience of physical space and while illumination...