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Glossary

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Passive (sensor): Sensor that only detects electromagnetic radiation which is naturally reflected or emitted by an object or a surface. As opposed to active sensors.

Photogrammetry: The science of making measurements from photographs. This encompasses a range of scale-independent techniques and concepts, see for instance image-based modelling and structure-from-motion.

Pixel: Smallest unit of a digital image that can be individually processed or manipulated. An image is made up of a collection of pixels. Sensors capture data by dividing the observed area into a grid of numerous pixels, with each pixel storing specific information about the observed object or surface.

Platform: Structure or vehicle to which a sensor is attached.

Point cloud: Discrete set of data points in a three-dimensional space, with values describing their location and possibly other attributes.

Postprocessing: Set of operations and techniques used for the removal of errors encountered while collecting remotely sensed or geophysical prospection data to get as close as possible to the true measured value and spatial characteristics of the study area at the time of data collection. Examples of postprocessing procedures include radiometric calibration, atmospheric correction, and geometric correction.

Precision: Closeness of a repeated set of observations of the same quantity to one another.

Probe separation (Electrical Resistivity Survey): The distance between electrodes (probes) placed in the ground to measure electrical resistance. The distance between the probes determines the depth and resolution of the measurement: a larger separation measures deeper but with less detail, while a smaller separation provides more detail at shallower depths.