Visual Resources Glossary

Select a letter from the list below to view glossary terms and acronyms/abbreviations. The agency abbreviation following the definition indicates the definition source.

A B C D E F G H I K L M N O P Q R S T U V W

Adverse visual impact: Any modification in landforms, water bodies, or vegetation or any introduction of structures that negatively interrupts the visual character of the landscape and disrupts the harmony of the basic elements (i.e., form, line, color, and texture). (BLM)
Aesthetic: The pleasurable characteristics of a physical environment as perceived through the five senses of sight, sound, smell, taste, and touch. (BLM); The study, science, or philosophy dealing with beauty and with judgments concerning beauty. In scenery management, it describes landscapes that give visual and sensory pleasure. (USFS)
Affected Environment: As defined by the National Environmental Policy Act, this is the “environment of the area(s) to be affected or created by the alternatives under consideration” (40 CFR 1502.15). (FHWA)
Agricultural (landscape character type): Landscapes that consist primarily of planted fields of row crops, orchards, vineyards, and livestock pasture or confined feeding operations. The topography is typically flat to rolling, but generally does not occur on steep terrain. These landscapes are often developed in grid-like field patters with a clustered farm complex. (NPS)
Air quality: A measurement of the pollutants in the air; a description of healthiness and safety of the atmosphere. (BLM)
Angle of observation: The angle, both vertical and horizontal, between a viewer’s line of sight and the landscape being viewed. (BLM)
Animation: A sequence of still images combined to create the appearance of movement. When used for visual simulations, movement depicted in an animation may be of either the project components or the viewer location and shows change in the appearance of the project and the surrounding scene over time. (NPS)
Area of analysis: The geographic area or areas to be included in a visual impact analysis. (NPS)
Area of Critical Environmental Concern (ACEC): Areas within the public lands where special management attention is required to protect or prevent irreparable damage to important values, which may include scenic values. (BLM)
Area of Visual Effect (AVE): The area in which views of the project would be visible as influenced by the presence or absence of intervening topography, vegetation, and structures. (FHWA)
Aspect: The positioning of an object in a specified direction; the direction that something (such as a building) faces or points toward. The aspect combined with the bearing determines which side of a facility is in view from a particular viewpoint, as well as the angle of the object’s vertical surfaces with respect to the viewer. (NPS)
Atmospheric Refraction: The deviation of light from a straight line as it passes through the atmosphere due to the variation in air density as a function of altitude. (NPS)
Azimuth: The horizontal angular distance from a reference direction, usually the northern point of the horizon to the point where a vertical circle through a celestial body (e.g., the sun) intersects the horizon, usually measured clockwise. (NPS)