Glossary
Absorption: Process by which electromagnetic radiation is absorbed through interaction with objects, surfaces, and the atmosphere and converted into other forms of energy.
Absorptance: Degree to which an object or surface absorbs electromagnetic radiation.
Accuracy: Degree to which a measured value conforms to true or accepted values. Accuracy is a measure of correctness. It is distinguished from precision, which measures exactness, and from resolution, which measures the density of measurements.
Acoustic (technique): Technique that uses sound waves to study, measure, or map the properties of objects or structures.
Acoustic impedance: The degree to which an object or surface resists the propagation of a sound wave. Acoustic impedance is calculated as the product of the propagation speed of the sound wave in the medium and the density of that medium.
Active (sensor): Sensors that produce and emit electromagnetic radiation and then record the energy which is reflected back from an object or a surface. As opposed to passive sensors.
Amplitude: In LiDAR remote sensing, the strength or intensity of the reflected signal that returns to the sensor. It indicates how much light is reflected by the surface of an object. A higher amplitude often signifies a better-reflecting surface, such as a hard or shiny surface, while a lower amplitude may indicate a less reflective surface, like grass or shadow.
AMZ cycle: The systematic process of identifying, valuing, and preserving archaeological remains in The Netherlands.
Analogue aerial photography: Type of aerial photography which utilizes analogue film cameras. Light which is captured by the lens is recorded on a photosensitive film. Through chemical processing, this latent image is then made visible and insensitive to light. These photographs are then ready to be printed using further chemical processing.
Anomaly: Deviation from the expected or standard value. Anomalies are mostly identified through contrasts in sensor readings. If an anomaly cannot be clearly identified as natural or modern in origin, it could potentially be archaeological in nature.
Anthropogenic: (Directly or indirectly) caused by human activity.
Atmosphere: Layer of gases surrounding planet Earth. As electromagnetic radiation travels through the atmosphere, energy can be absorbed and scattered. This leads to attenuation and a degradation of the remote sensing image quality. This can be corrected during image pre-processing by atmospheric calibration.
Atmospheric calibration: Correcting the disturbances caused by the atmosphere’s attenuation and absorption of the electromagnetic radiation on a remote sensing image.
Attenuation: Reduction in the strength of a signal.
Autonomous Underwater Vehicle (AUV): Unmanned, self-navigating devices equipped with sensors and other instruments to independently collect underwater data.