DIGITAL IMAGE ACQUISITION AND STORAGE

Passive Sensing

Sensors record reflected or emitted electromagnetic radiation from natural sources without disturbing the object.

Active Sensing

Sensors emit their own energy such as microwave sound or light pulses and record the return.

Pixel

Picture elements arranged in rows and columns that form a two dimensional digital image.

Brightness Value

Proxy digital value for radiance that provides a visual idea of energy reflected or emitted from a ground area.

Instantaneous Field of View

What the sensor detector sees as it passes over a target.

Ground Resolution Element

The ground segment sensed by the instantaneous field of view.

Across Track Scanning

Whiskbroom scanning using discrete detectors and a rotating mirror perpendicular to sensor motion.

Along Track Scanning

Pushbroom scanning using linear and area detector arrays along the line of flight.

Dwell Time

Amount of time a sensor spends collecting photons from an instantaneous field of view.

Spatial Resolution

Size of the smallest feature that can be detected by a sensor or displayed in an image.

Spectral Resolution

Number and width of specific wavelength bandwidths captured by a sensor system.

Multispectral Sensor

Sensor collecting data in two or more broad spectral bands typically five to ten.

Hyperspectral Sensor

Sensor collecting data in hundreds of narrow spectral bands.

Radiometric Resolution

Number of different brightness values or intensity levels a sensor can record expressed in bits.

Bit Depth

Quantization level determining how many total intensity values a pixel can store.

Temporal Resolution

Time interval or revisit time between successive sensor passes over the same area.

Geostationary Orbit

Satellite orbits at the same angular velocity as Earth to remain fixed over one location.

Polar Orbit

Satellite passes over the poles gathering global data swath by swath as Earth rotates.

Satellite Constellation

Group of identical sensors on multiple satellites used to increase temporal coverage.

Photogrammetry

Science and technology of obtaining reliable measurements and physical dimensions of objects through photographs and digital sensors.

Suborbital Platform

Airborne data collection vehicle operating within Earth atmosphere such as helicopters airplanes or drones.

Orbital Platform

Spaceborne object traveling outside Earth atmosphere such as space shuttles or satellites.

Ground Projected IFOV

Circular or elliptical region on Earth surface that corresponds to the instantaneous field of view of a sensor system at a specific altitude.

Quantitative Biophysical Attribute

Measurable physical biological or chemical characteristic of the environment such as ground temperature elevation or biomass.

Dichotomy in Remote Sensing

Separation between acquiring raw energy patterns from a physical landscape and interpreting or inferring meaningful geographic information from that captured image.

Spatial Perspective

Geographic scale and point of view from which a sensor collects data ranging from ground level up to suborbital platforms and orbital satellites.

Multi Temporal

Collection of remote sensing data over the same geographic area at multiple different points in time to monitor change.