Glossary
Data model: Abstraction and/or formalisation of objects and relationships, including the set of concepts (entities, attributes, relationships) used to describe such formalisations.
Differential GPS (DGPS): Enhancement to the standard GPS system that improves location accuracy. It uses a network of fixed ground-based reference stations to register and broadcast the difference between the positions indicated by the GPS satellites and the known fixed positions. This correction information is then used by DGPS receivers to provide more precise positioning data.
Diffraction hyperbola: Anomalies in a seismic profile acquired using a Sub-Bottom Profiler.
Digital Elevation Model (DEM): Digital representation of the topographic surface of the earth based on elevation values.
Digital Terrain Model (DTM): Type of Digital Elevation Model (DEM) that displays the topographic surface without anthropogenic objects and surface vegetation.
Digital Surface Model (DSM): Type of Digital Elevation Model (DEM) that displays all anthropogenic and natural objects as well as the topographic surface.
Diode: Type of semiconductor that allows current in a single direction, e.g. a photodiode that produces current when light falls on it.
Downwelling Light Sensor (DLS): A Downwelling Light Sensor (DLS) is a sensor that measures the amount of incoming light from above (usually sunlight) that reaches a surface. DLS data allows for compensation of variations in ambient light caused by factors such as cloud cover or the position of the sun, resulting in more accurate and consistent reflectance measurements.
Drone: Remote-controlled or autonomous unmanned aerial vehicle. Drones can be used as a platform for sensors. Also RPAS, UAS, UAV.