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Glossary

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

Raster image: A visual data structure of a grid with pixels, where each pixel represents a value.

Raw data: Data collected by a sensor which has not been processed.

Reality-based modelling: Process of creating digital models which closely resemble real-world objects, phenomena, or systems, aiming for accuracy and authenticity in representation.

Reflection: Bouncing back of electromagnetic radiation or soundwaves through the interaction object or surface into the medium which originally emitted the radiation.

Reflection coefficient (Side Scan Sonar): A measure of the strength of the sound wave that reflects off a surface and returns to the sonar receiver.

Reflectivity: Degree to which an object or surface reflects electromagnetic radiation.

Reflector (GPR): A boundary between two materials or sediment layers with a significant difference in composition, by which a GPR radar wave is partially reflected.

Reflector (Sub-Bottom Profiler): A boundary between two materials or sediment layers with a significant difference in acoustic impedance, where a sound wave is partially reflected. In seismic studies, a reflector appears as a distinguishable layer or line in a seismic profile.

Remote sensing: Collective term for non-destructive techniques that collect data on the earth’s surface from a certain height (distance).

Remotely Operated Vehicle (ROV): A Remotely Operated Vehicle used for underwater research and inspection. ROVs are unmanned, often remotely controlled devices equipped with cameras, sensors, and other instruments to collect data and perform tasks in marine environments.

Resolution (spectral, spatial, radiometric, temporal): The level of detail and accuracy provided by the imagery. Several different types of resolution can be distinguished.

  • Spectral resolution: the ability of a sensor to distinguish between different ranges of wavelength intervals.
  • Spatial resolution: the smallest object that can be detected on the imagery. Spatial resolution is expressed as the length of one side of a pixel in the image.
  • Radiometric resolution: how accurately a sensor can represent subtle differences in electromagnetic radiation. This is represented by the number of bits in each pixel of an image.
  • Temporal resolution: the revisit time to acquire data about the same location, predominantly used in relation to satellite-based remote sensing.

RPAS: Remotely Piloted Aircraft System. See also drone, UAS, UAV.

RTK (Real-Time Kinematic): A precise positioning technique that uses GNSS correction signals to determine the location of a receiver with centimetre-level accuracy. This system operates by transmitting real-time corrections from a base station to a mobile receiver, significantly reducing errors in GNSS measurements.