Visibility

Visibility refers to whether an object can be visually detected under the relevant viewing conditions. Conspicuity refers more specifically to how readily the object attracts attention or stands out from its surroundings and competing visual information. An object may therefore be within an unobstructed line of sight and capable of being seen without necessarily being highly conspicuous. Contrast, lighting, background complexity, motion, and competing visual information can all affect this distinction.

No. Photographs and surveillance video do not necessarily reproduce what a person could see because cameras differ from human vision in viewpoint, lens characteristics, field of view, exposure, sensor response, frame rate, compression, and image processing. Camera location may also differ from the observer's position, and low-light performance can vary substantially among devices. Images and video can still provide useful evidence about scene conditions, geometry, and timing, but they should be interpreted with known camera characteristics and viewing conditions rather than treated as exact reproductions of human perception.

Low contrast between an object and its background can make the object more difficult to detect, particularly under low-light conditions. Glare can further reduce visual performance by decreasing effective contrast or interfering with the ability to distinguish objects elsewhere in the visual field. A visibility analysis may therefore consider object and background luminance, contrast, illumination, glare sources, viewing geometry, and other scene conditions rather than relying on viewing distance alone.