This glossary explains the imagery, mapping, sensing, and data standards used across the Geospatial & Earth-observation Analytics Practice. Within Technology & Telecom, it helps executives and practitioners interpret technical specifications, assess data quality, and navigate geospatial products, platforms, and regulatory requirements.
0–9 A B C D E F G H I J K L M N O P Q R S T U V W
| 0–9 | |
| 3DEP | 3D Elevation Program: A United States Geological Survey program acquiring high-quality elevation data to support mapping, flood-risk assessment, infrastructure planning, and other terrain-dependent applications. |
| 3DHP | 3D Hydrography Program: A United States Geological Survey program developing elevation-derived hydrography and connected water-network data for hydrologic analysis, mapping, and water-resource management. |
| A | |
| AASR | Azimuth Ambiguity-to-Signal Ratio: A radar image-quality metric comparing unwanted azimuth-ambiguous energy with the desired signal. Lower values indicate less contamination from targets displaced along the flight direction. |
| AC | Atmospheric Correction: Processing that compensates for atmospheric scattering and absorption in optical observations, enabling more reliable surface-reflectance retrieval and comparison across acquisition dates. |
| AERONET | Aerosol Robotic Network: A ground-based sun-photometer network providing aerosol measurements used to validate satellite products and support atmospheric correction of remotely sensed imagery. |
| ALOS | Advanced Land Observing Satellite: A Japanese satellite program supplying land-observation data for mapping, disaster monitoring, and environmental analysis, including widely used radar imagery and elevation products. |
| AOD | Aerosol Optical Depth: A dimensionless measure of light extinction by aerosols through an atmospheric column. It supports air-quality analysis, atmospheric correction, and aerosol-product validation. |
| AOI | Area of Interest: The geographic boundary selected for imagery acquisition, data procurement, processing, or analysis. Its size and location influence coverage, delivery requirements, and pricing. |
| ARD | Analysis Ready Data: Observations processed to defined geometric, radiometric, and metadata requirements so users can analyze them with limited additional preparation and more consistent results. |
| ASPRS | American Society for Photogrammetry and Remote Sensing: A professional society developing geospatial standards, positional-accuracy guidance, and practitioner certifications relevant to imagery, elevation data, and mapping deliverables. |
| ASTER | Advanced Spaceborne Thermal Emission and Reflection Radiometer: An instrument aboard Terra whose imagery supports geological interpretation, surface-temperature analysis, and elevation mapping through multispectral observations and along-track stereo imaging. |
| ATLAS | Advanced Topographic Laser Altimeter System: The photon-counting laser instrument aboard the second Ice, Cloud, and land Elevation Satellite, measuring ice, vegetation, water, and land-surface heights. |
| AVHRR | Advanced Very High Resolution Radiometer: A long-running satellite radiometer series providing observations used in vegetation monitoring, cloud detection, sea-surface temperature retrieval, and historical environmental records. |
| AVIRIS | Airborne Visible/Infrared Imaging Spectrometer: An airborne imaging-spectrometer system collecting contiguous spectral measurements for material identification, ecosystem analysis, mineral mapping, and development of satellite retrieval methods. |
| B | |
| BA | Bundle Adjustment: A photogrammetric optimization that jointly refines camera parameters and three-dimensional point positions, improving the geometric consistency and accuracy of overlapping imagery. |
| BDS | BeiDou Navigation Satellite System: China’s global satellite-navigation system, used with other constellations to improve positioning availability and geometry for surveying, mobile mapping, and georeferencing. |
| BIL | Band Interleaved by Line: A multiband raster storage layout that writes each image line’s bands consecutively. Storage organization affects reading efficiency and compatibility with image-processing software. |
| BIP | Band Interleaved by Pixel: A raster storage layout grouping all spectral-band values for each pixel together, supporting workflows that repeatedly access complete pixel spectra. |
| BOA | Bottom of Atmosphere: The surface-level reference for radiometric measurements. Reflectance products at this level compensate for atmospheric effects to better represent ground and vegetation properties. |
| BRDF | Bidirectional Reflectance Distribution Function: A function describing how surface reflectance varies with illumination and viewing directions. It supports angular normalization and consistent comparison of observations. |
| BRF | Bidirectional Reflectance Factor: The ratio of a surface’s reflected radiance to that of an ideal diffuse reflector under equivalent illumination, used to characterize directional reflectance. |
| BSQ | Band Sequential: A raster storage layout containing one complete spectral band after another, making it efficient to access or process individual image bands. |
| C | |
| CARD4L | CEOS Analysis Ready Data for Land: A framework defining processing, metadata, and quality requirements for land-observation products, improving interoperability and reducing preparation needed before analysis. |
| CCM | Copernicus Contributing Missions: Satellite missions supplying data to Copernicus in addition to the Sentinel missions, extending available observation capabilities, spatial resolution, and coverage. |
| CE90 | Circular Error at 90% Confidence: A horizontal positional-accuracy measure expressing the radius expected to contain 90% of location errors, used in imagery specifications and geolocation acceptance criteria. |
| CEOS | Committee on Earth Observation Satellites: An international coordination body for civil space-based Earth observation, supporting mission coordination, data interoperability, calibration, validation, and analysis-ready product requirements. |
| CF | Climate and Forecast Metadata Conventions: Metadata conventions describing scientific variables, coordinates, and related information in gridded datasets, enabling software to interpret and combine environmental observations correctly. |
| CHM | Canopy Height Model: A raster representing vegetation height above the ground, commonly derived by subtracting terrain elevations from surface elevations for forestry and biomass analysis. |
| CIR | Color Infrared: An image presentation assigning near-infrared and visible bands to display colors, making vegetation condition and land-cover differences easier to interpret. |
| CLMS | Copernicus Land Monitoring Service: A Copernicus service providing land-cover, land-use, vegetation, and surface-condition information for environmental monitoring, planning, and change analysis. |
| CMEMS | Copernicus Marine Environment Monitoring Service: A service combining satellite observations, in-situ measurements, and models to deliver information on ocean physical and biogeochemical conditions. |
| COG | Cloud Optimized GeoTIFF: A georeferenced raster layout using internal organization and overviews to support efficient remote access to selected image regions without downloading the entire file. |
| CORS | Continuously Operating Reference Station: A permanent satellite-navigation receiver providing observations and reference coordinates for precise positioning, survey control, and geospatial datum realization. |
| CRS | Coordinate Reference System: A framework connecting coordinates to real-world locations through a datum and coordinate system. Correct identification is essential when combining or transforming spatial datasets. |
| CRSRA | Commercial Remote Sensing Regulatory Affairs: The regulatory function within the United States Office of Space Commerce that administers licensing and compliance for private remote-sensing space systems. |
| CSW | Catalogue Service for the Web: An Open Geospatial Consortium standard for discovering geospatial resources through searchable metadata catalogs, supporting data inventories and interoperable discovery services. |
| D | |
| DAAC | Distributed Active Archive Center: A discipline-focused archive within the United States civilian Earth-science data system, providing stewardship, distribution, documentation, and user support for observation datasets. |
| DART | Discrete Anisotropic Radiative Transfer: A three-dimensional radiative-transfer model that simulates interactions between radiation, landscapes, and the atmosphere for sensor simulation and remote-sensing interpretation. |
| DE-9IM | Dimensionally Extended 9-Intersection Model: A formal model describing topological relationships between geometries through intersections of their interiors, boundaries, and exteriors, underpinning standardized spatial predicates. |
| DEM | Digital Elevation Model: A digital representation of elevation used in terrain analysis, orthorectification, hydrologic modeling, and visibility studies. Product specifications determine whether surface objects are included. |
| DGGS | Discrete Global Grid System: A hierarchical partition of Earth into uniquely identified cells, supporting consistent indexing, aggregation, and analysis of spatial information across scales. |
| DGNSS | Differential Global Navigation Satellite System: Positioning that uses reference-station information to reduce errors in satellite-navigation measurements, improving accuracy for surveying, mapping, and field data collection. |
| DGPS | Differential Global Positioning System: A reference-based correction technique for the United States satellite-navigation constellation, used to improve positioning accuracy in mapping and survey workflows. |
| DInSAR | Differential Interferometric Synthetic Aperture Radar: A technique that removes modeled topographic phase from radar interferograms to estimate surface displacement along the sensor’s line of sight. |
| DN | Digital Number: A numerical pixel value recorded or stored by an imaging system. Calibration information is needed to convert it into physical quantities such as radiance. |
| DNB | Day/Night Band: A low-light imaging band on the Visible Infrared Imaging Radiometer Suite, used to observe nighttime illumination, clouds, fishing activity, and power outages. |
| dNBR | Differenced Normalized Burn Ratio: The difference between pre-fire and post-fire burn-index values, used to map fire-related change and assess burn severity with appropriate local calibration. |
| DOP | Dilution of Precision: A measure of how satellite geometry amplifies ranging errors into positioning uncertainty. Lower values generally indicate more favorable geometry for survey observations. |
| DORIS | Doppler Orbitography and Radiopositioning Integrated by Satellite: A satellite-tracking system using signals from ground beacons to determine precise orbits and support geodetic reference frames and satellite-altimetry accuracy. |
| DSM | Digital Surface Model: An elevation representation of the upper visible surface, including buildings and vegetation, used for urban modeling, visibility analysis, and canopy-height derivation. |
| DTED | Digital Terrain Elevation Data: A standardized gridded terrain-elevation product organized into defined levels, supporting interoperability in defense mapping, navigation, and terrain analysis. |
| DTM | Digital Terrain Model: A representation of bare-earth terrain, sometimes including breaklines and other terrain structure, used for engineering, drainage analysis, and elevation correction. |
| E | |
| ECEF | Earth-Centered, Earth-Fixed: A three-dimensional Cartesian coordinate frame centered on Earth and rotating with it, used in satellite positioning, orbit calculations, and geospatial transformations. |
| ECOSTRESS | Ecosystem Spaceborne Thermal Radiometer Experiment on Space Station: A space-station thermal-imaging experiment supporting estimates of vegetation water stress, evapotranspiration, and land-surface temperature at varying times of day. |
| ECV | Essential Climate Variable: A physical, chemical, or biological variable identified as necessary for climate monitoring, guiding observation requirements and the development of consistent long-term datasets. |
| EGM | Earth Gravitational Model: A model of Earth’s gravity field used to derive geoid information and support height conversion, orbit analysis, and consistent vertical referencing. |
| EGNOS | European Geostationary Navigation Overlay Service: A European satellite-based augmentation service providing navigation corrections and integrity information, improving positioning reliability for supported mapping and field operations. |
| EMIT | Earth Surface Mineral Dust Source Investigation: A space-station imaging-spectroscopy mission mapping surface minerals in dust-source regions, with observations also supporting detection of large methane and carbon-dioxide emission plumes. |
| EnMAP | Environmental Mapping and Analysis Program: A German hyperspectral satellite mission providing detailed spectral measurements for environmental monitoring, mineral identification, vegetation analysis, and land-surface characterization. |
| ENVI | Environment for Visualizing Images: Commercial software for processing and analyzing remotely sensed imagery, including spectral analysis, classification, atmospheric correction, and integration with mapping workflows. |
| EO | Earth Observation: The collection and interpretation of information about Earth’s surface and atmosphere using satellites, aircraft, and other observing systems to support monitoring and decisions. |
| EOS | Earth Observing System: A United States civilian space-science program integrating satellite missions and associated research to study Earth’s atmosphere, oceans, land, ice, and their interactions. |
| EOSDIS | Earth Observing System Data and Information System: The data infrastructure supporting archiving, discovery, distribution, and use of United States civilian Earth-science observations and derived products. |
| EPSG | European Petroleum Survey Group: The group that originated a widely used geodetic registry, now maintained by the International Association of Oil & Gas Producers, identifying coordinate systems and transformations. |
| ESA | European Space Agency: An intergovernmental space agency developing and operating Earth-observation missions and supporting data access, scientific exploitation, calibration, and downstream geospatial applications. |
| ESDA | Exploratory Spatial Data Analysis: Methods for investigating geographic distributions, spatial dependence, clusters, and outliers before formal modeling, helping analysts identify patterns and potential data problems. |
| ETM+ | Enhanced Thematic Mapper Plus: The Landsat 7 imaging instrument, whose multispectral, thermal, and panchromatic archive supports long-term land-change analysis and cross-mission comparisons. |
| EVI | Enhanced Vegetation Index: A vegetation index using near-infrared, red, and blue reflectance to improve sensitivity in dense vegetation while reducing atmospheric and soil-background influences. |
| EVI2 | Two-Band Enhanced Vegetation Index: A red and near-infrared vegetation index designed to approximate the three-band version without requiring a blue band, supporting broader sensor compatibility. |
| EW | Extra Wide Swath: A Sentinel-1 acquisition mode prioritizing broad radar coverage over finer spatial detail, particularly useful for sea-ice surveillance and maritime monitoring. |
| F | |
| FAA | Federal Aviation Administration: The United States aviation regulator governing aerial mapping operations, including small-drone pilot requirements, operating restrictions, airspace authorizations, and relevant waivers. |
| FAPAR | Fraction of Absorbed Photosynthetically Active Radiation: The fraction of incoming photosynthetically active radiation absorbed by vegetation, used in productivity estimation, ecosystem modeling, and vegetation-condition monitoring. |
| FCC | False Color Composite: An image combining spectral bands into display colors that differ from natural appearance, highlighting vegetation, water, geology, or other features. |
| FES | Filter Encoding Standard: An Open Geospatial Consortium standard expressing spatial and attribute filters, allowing interoperable queries against geospatial features and related resources. |
| FGDC | Federal Geographic Data Committee: A United States interagency body coordinating geospatial data standards, policies, and national spatial-data infrastructure to improve sharing and reduce duplication. |
| FIRMS | Fire Information for Resource Management System: A service distributing satellite-derived active-fire and thermal-anomaly information for wildfire monitoring, situational awareness, and geospatial analysis. |
| FOSS4G | Free and Open Source Software for Geospatial: Geospatial software available under licenses permitting use, inspection, modification, and redistribution. The term also names a major geospatial open-source conference series. |
| FOV | Field of View: The angular extent observed by a sensor, influencing ground coverage, swath width, and acquisition planning at a given platform altitude. |
| FRP | Fire Radiative Power: The rate of radiant energy released by a fire, estimated from thermal observations and used to assess fire activity and combustion-related emissions. |
| FVC | Fractional Vegetation Cover: The proportion of a ground area covered by vegetation, estimated from imagery for land degradation assessment, erosion modeling, and ecosystem monitoring. |
| FWHM | Full Width at Half Maximum: The width of a response function at half its peak value, used to specify spectral bandwidth or characterize spatial image response. |
| G | |
| GCOS | Global Climate Observing System: An international program defining and coordinating climate-observation needs, including requirements for essential variables measured through satellites and ground-based networks. |
| GCP | Ground Control Point: A clearly identifiable location with known coordinates used to georeference imagery or constrain photogrammetric models. Independent checkpoints are needed to evaluate resulting accuracy. |
| GCS | Geographic Coordinate System: A spatial reference using angular coordinates, usually latitude and longitude, tied to a geodetic datum rather than a planar map projection. |
| GDAL | Geospatial Data Abstraction Library: An open-source library and toolset for reading, writing, translating, and processing raster and vector geospatial formats across analytics platforms. |
| GEE | Google Earth Engine: A cloud-based platform combining a geospatial data catalog with large-scale computation for satellite-image analysis, environmental monitoring, and time-series processing. |
| GEO | Group on Earth Observations: An intergovernmental partnership promoting coordinated Earth observations and their use in addressing environmental, societal, and economic challenges. |
| GEOBIA | Geographic Object-Based Image Analysis: An approach that segments imagery into meaningful objects and analyzes their spectral, spatial, and contextual properties for classification and feature extraction. |
| GEOINT | Geospatial Intelligence: Information produced by analyzing imagery and geospatial data to describe activities and features on Earth, supporting security, operational planning, and situational awareness. |
| GEOSS | Global Earth Observation System of Systems: A coordinated framework connecting observation systems and information resources to improve access to Earth-observation data across disciplines and organizations. |
| GFOI | Global Forest Observations Initiative: An international partnership supporting national forest monitoring through observation coordination, methods guidance, research, and capacity development for forest and carbon reporting. |
| GIS | Geographic Information System: A system for managing, analyzing, and visualizing location-referenced information, integrating imagery, vector features, terrain, and attributes to support spatial decisions. |
| GLAS | Geoscience Laser Altimeter System: The laser-altimetry instrument on the original Ice, Cloud, and land Elevation Satellite, providing elevation and waveform observations for ice, terrain, and vegetation studies. |
| GLONASS | Global Navigation Satellite System: Russia’s satellite-navigation constellation, commonly combined with other constellations to improve positioning availability and satellite geometry in surveying and mapping. |
| GML | Geography Markup Language: An Open Geospatial Consortium encoding for geographic features, geometries, and properties, supporting structured exchange of spatial information between systems. |
| GNDVI | Green Normalized Difference Vegetation Index: A vegetation index comparing near-infrared and green reflectance, used to assess canopy condition and chlorophyll-related variation in agricultural and ecological applications. |
| GNSS | Global Navigation Satellite System: The general category of satellite-based positioning systems, including multiple national and regional constellations, used for surveying, sensor positioning, and georeferencing. |
| GNSS-R | Global Navigation Satellite System Reflectometry: Remote sensing that analyzes navigation signals reflected from Earth’s surface to estimate properties such as ocean roughness, soil moisture, and surface height. |
| GOES | Geostationary Operational Environmental Satellite: A United States weather-satellite series providing frequent regional observations for cloud analysis, severe-weather monitoring, fire detection, and atmospheric products. |
| GPM | Global Precipitation Measurement: An international satellite-observation mission that combines a core observatory with partner sensors to estimate precipitation for hydrology, weather, and disaster applications. |
| GPP | Gross Primary Productivity: The rate at which vegetation fixes carbon through photosynthesis, estimated using observations and models to assess ecosystem productivity and carbon-cycle dynamics. |
| GPS | Global Positioning System: The United States satellite-navigation system, providing positioning observations used in field mapping, survey control, aerial acquisition, and geospatial data collection. |
| GRACE | Gravity Recovery and Climate Experiment: A satellite mission whose gravity measurements reveal large-scale mass redistribution, supporting analysis of groundwater, ice loss, and terrestrial water storage. |
| GRASS | Geographic Resources Analysis Support System: An open-source geospatial software system supporting raster, vector, imagery, and temporal analysis for terrain modeling, environmental assessment, and scientific workflows. |
| GRD | Ground Range Detected: A radar product containing detected, usually multilooked imagery projected into ground range. Phase is not retained, and additional terrain correction may be required. |
| GRIB | General Regularly-distributed Information in Binary form: A standardized binary format for gridded meteorological information, commonly encountered when combining Earth observations with forecasts, reanalysis, and atmospheric model fields. |
| GSD | Ground Sample Distance: The ground spacing represented by adjacent image samples, used to specify image scale and acquisition requirements. It does not alone determine effective resolving power. |
| GWR | Geographically Weighted Regression: A spatial modeling technique estimating location-specific relationships between variables, helping analysts identify geographic variation that a single global regression can conceal. |
| H | |
| HDF | Hierarchical Data Format: A family of scientific data formats organizing arrays, metadata, and related datasets within a file, widely used for satellite observations and derived products. |
| HDOP | Horizontal Dilution of Precision: A satellite-geometry factor describing amplification of measurement errors into horizontal positioning uncertainty, used when evaluating field-survey and navigation conditions. |
| HLS | Harmonized Landsat Sentinel-2: A coordinated surface-reflectance dataset that harmonizes Landsat and Sentinel-2 observations on a common grid to support denser, more consistent land-monitoring time series. |
| HSI | Hyperspectral Imaging: Imaging across many narrow, usually contiguous spectral bands, enabling discrimination of materials and retrieval of properties not readily separated with broad-band imagery. |
| I | |
| ICESat | Ice, Cloud, and land Elevation Satellite: A satellite mission designation associated with laser measurements of ice and land elevation, supporting ice-sheet change, vegetation structure, and surface-height analysis. |
| IFOV | Instantaneous Field of View: The angular area observed by an individual detector element at a given instant, contributing to the ground footprint and spatial sampling of imagery. |
| IGS | International GNSS Service: An international service providing precise satellite orbits, clocks, station information, and related products for high-accuracy positioning and geodetic research. |
| IMU | Inertial Measurement Unit: A sensor package measuring acceleration and angular motion, used with navigation observations to determine camera or laser-scanner orientation during aerial and mobile mapping. |
| InSAR | Interferometric Synthetic Aperture Radar: A technique comparing the phase of radar observations to measure terrain elevation or surface displacement, supporting subsidence, infrastructure, volcanic, and earthquake monitoring. |
| INSPIRE | Infrastructure for Spatial Information in the European Community: A European Union legal framework establishing requirements for interoperable environmental spatial information, including metadata, network services, and harmonized data specifications. |
| ISPRS | International Society for Photogrammetry and Remote Sensing: An international scientific organization advancing photogrammetry, remote sensing, and spatial-information science through research coordination, technical exchange, and professional activities. |
| ISRO | Indian Space Research Organisation: India’s space agency, developing Earth-observation missions and applications that supply imagery and environmental information for resource management, mapping, and disaster response. |
| ITRF | International Terrestrial Reference Frame: A practical realization of the international terrestrial reference system through station coordinates and velocities, enabling consistent global positioning across locations and epochs. |
| ITRS | International Terrestrial Reference System: The conceptual Earth-fixed reference system defining origin, scale, orientation, and temporal behavior for precise global geodesy and coordinate-frame realizations. |
| IW | Interferometric Wide Swath: A principal Sentinel-1 land-acquisition mode balancing broad coverage with spatial resolution, widely used for radar mapping and repeat-pass deformation analysis. |
| J | |
| JAXA | Japan Aerospace Exploration Agency: Japan’s national aerospace agency, operating Earth-observation missions and producing radar, precipitation, climate, and land-monitoring datasets used internationally. |
| JPSS | Joint Polar Satellite System: A United States polar-orbiting environmental satellite program supplying observations for weather prediction, atmospheric sounding, ocean monitoring, and land-surface products. |
| K | |
| KBA | Kyl-Bingaman Amendment: A United States law restricting licensed commercial satellite imagery of Israel to detail or precision comparable to imagery available from non-United States commercial sources. |
| KML | Keyhole Markup Language: An Open Geospatial Consortium standard for encoding geographic features, imagery overlays, and visualization instructions for display in mapping applications and virtual globes. |
| L | |
| LAI | Leaf Area Index: A measure of leaf area per unit ground area, retrieved from observations to characterize canopy structure and support crop, ecosystem, and water-balance models. |
| LE90 | Linear Error at 90% Confidence: A one-dimensional accuracy measure, commonly applied to elevation, specifying an absolute error threshold expected to contain 90% of errors. |
| LiDAR | Light Detection and Ranging: Active sensing that measures distance using laser light, producing elevation and three-dimensional point data for terrain, vegetation, infrastructure, and bathymetric mapping. |
| LISA | Local Indicators of Spatial Association: Local spatial statistics identifying clusters and outliers within geographic data, supporting hotspot analysis while requiring attention to significance testing and spatial-weight choices. |
| LST | Land Surface Temperature: The radiometric temperature of the land surface, retrieved primarily from thermal observations for heat-risk assessment, evapotranspiration modeling, and environmental monitoring. |
| LULC | Land Use and Land Cover: Classification of land’s physical cover and human use, providing a basis for change detection, planning, environmental assessment, and resource management. |
| M | |
| MAI | Multi-Aperture Interferometry: A radar-processing technique using different portions of the synthetic aperture to estimate along-track displacement, complementing conventional line-of-sight interferometric measurements. |
| MAUP | Modifiable Areal Unit Problem: The sensitivity of statistical results to the size and boundaries of geographic aggregation units, a critical consideration when interpreting spatial patterns and comparisons. |
| MESMA | Multiple Endmember Spectral Mixture Analysis: A spectral-unmixing approach allowing the number or identity of reference materials to vary by pixel, improving representation of heterogeneous landscapes. |
| MGRS | Military Grid Reference System: An alphanumeric geographic reference system based on transverse Mercator and polar stereographic grids, used for location reporting and operational map coordination. |
| MGWR | Multiscale Geographically Weighted Regression: A spatial regression method allowing explanatory relationships to operate at different geographic scales, improving interpretation of spatially varying processes. |
| MISR | Multi-angle Imaging SpectroRadiometer: An instrument aboard Terra observing Earth from multiple angles to retrieve aerosol, cloud, and surface properties and characterize directional reflectance. |
| MNDWI | Modified Normalized Difference Water Index: A green and shortwave-infrared reflectance index designed to enhance open water while suppressing built-up and other non-water surfaces. |
| MNF | Minimum Noise Fraction: A noise-aware image transformation separating spectral information by estimated signal quality, commonly used for hyperspectral dimensionality reduction and noise suppression. |
| MODIS | Moderate Resolution Imaging Spectroradiometer: An imaging instrument on Terra and Aqua supplying frequent global observations and widely used products for vegetation, fire, atmosphere, ocean, and snow monitoring. |
| MSAVI | Modified Soil-Adjusted Vegetation Index: A vegetation index designed to reduce soil-background effects using an adaptive adjustment, particularly useful where vegetation cover is sparse. |
| MSI | Multispectral Imaging: Imaging in several distinct spectral bands, enabling land-cover classification, vegetation assessment, water mapping, and other analyses beyond ordinary color photography. |
| MSI | Multispectral Instrument: The Sentinel-2 optical instrument acquiring 13 spectral bands at multiple spatial resolutions for land, vegetation, inland-water, and coastal monitoring. |
| MSS | Multispectral Scanner System: An imaging system carried by early Landsat satellites, providing a foundational historical archive for long-term land-cover and environmental-change analysis. |
| MTF | Modulation Transfer Function: A measure of how an imaging system preserves contrast at different spatial frequencies, providing a more complete assessment of image sharpness than pixel spacing alone. |
| MTI | Multi-Temporal Interferometry: Radar-interferometric analysis of repeated acquisitions to estimate displacement histories while reducing atmospheric, orbital, and other contributions to measurement error. |
| MWIR | Mid-Wave Infrared: An infrared spectral region commonly associated with wavelengths around three to five micrometers, useful for detecting high-temperature targets and active fires. |
| N | |
| NAD 83 | North American Datum of 1983: A geodetic datum widely used for North American mapping and surveying. Its realization and coordinate epoch matter when combining high-accuracy datasets. |
| NASA | National Aeronautics and Space Administration: The United States civilian space agency responsible for major Earth-science missions, open observation archives, research products, and applications supporting geospatial analysis. |
| NAVD 88 | North American Vertical Datum of 1988: A vertical datum widely used for United States elevation mapping and engineering, requiring explicit identification when integrating heights from different reference systems. |
| NBAR | Nadir BRDF-Adjusted Reflectance: Surface reflectance normalized to a nadir viewing geometry using a directional-reflectance model, reducing observation-angle effects in image mosaics and time-series analysis. |
| NBR | Normalized Burn Ratio: An index combining near-infrared and shortwave-infrared reflectance to identify burned areas and characterize fire-related changes in vegetation and surface conditions. |
| NDBI | Normalized Difference Built-up Index: An index contrasting shortwave-infrared and near-infrared reflectance to highlight built-up surfaces, although bare soil and other materials can produce similar responses. |
| NDMI | Normalized Difference Moisture Index: A near-infrared and shortwave-infrared index used to track vegetation moisture conditions and support drought, canopy-water, and disturbance monitoring. |
| NDRE | Normalized Difference Red Edge Index: A vegetation index comparing near-infrared and red-edge reflectance, used to assess chlorophyll-related canopy variation, including in relatively dense crops. |
| NDSI | Normalized Difference Snow Index: An index exploiting snow’s contrasting visible and shortwave-infrared reflectance to support snow-cover mapping and separation from many other bright surfaces. |
| NDVI | Normalized Difference Vegetation Index: A normalized comparison of near-infrared and red reflectance used to characterize vegetation greenness, seasonal development, and change across large areas. |
| NDWI | Normalized Difference Water Index: In open-water mapping, an index contrasting green and near-infrared reflectance to enhance water bodies and suppress many vegetation and land signals. |
| NDWI | Normalized Difference Water Index: In vegetation-water analysis, an index contrasting near-infrared and shortwave-infrared reflectance, originally using a band near 1.24 micrometers, to indicate canopy liquid-water content. |
| NEDT | Noise-Equivalent Differential Temperature: The temperature difference producing a signal comparable to instrument noise, used to specify thermal-sensor sensitivity and interpret temperature-retrieval precision. |
| NESZ | Noise-Equivalent Sigma Zero: The normalized radar backscatter level corresponding to a sensor’s noise floor, indicating its ability to distinguish weak returns from noise. |
| netCDF | Network Common Data Form: A scientific data format and supporting software interfaces for multidimensional arrays, widely used for gridded observations, climate records, and environmental-model outputs. |
| NGA | National Geospatial-Intelligence Agency: A United States agency producing geospatial intelligence and maintaining important geospatial standards, reference products, and imagery-related requirements for defense and security users. |
| NIR | Near-Infrared: The infrared region adjacent to visible red light, widely used to distinguish vegetation, identify water, and calculate land-monitoring spectral indices. |
| NISAR | NASA-ISRO Synthetic Aperture Radar: A joint United States–Indian radar mission designed to measure land deformation, ecosystem change, and ice dynamics through repeated observations at two radar wavelengths. |
| NITF | National Imagery Transmission Format: A standardized container for imagery and associated metadata, widely used in defense and intelligence workflows requiring structured geolocation and exploitation information. |
| NLCD | National Land Cover Database: A United States land-cover data program supplying standardized thematic products for land-change analysis, environmental assessment, and integration with other national datasets. |
| NOAA | National Oceanic and Atmospheric Administration: A United States agency operating environmental satellites and providing ocean, atmosphere, climate, and geodetic information, while overseeing commercial space-based remote-sensing licensing. |
| NPP | National Polar-orbiting Partnership: A designation in the Suomi satellite’s name, associated with instruments supporting weather monitoring, nighttime-light observations, and long-term environmental data continuity. |
| NPP | Net Primary Productivity: Vegetation carbon accumulation after subtracting plant respiration from gross photosynthetic production, used in biomass assessment, ecosystem monitoring, and carbon accounting. |
| NRT | Near Real Time: Data availability with a short, specified delay after observation, important for fire response, flood monitoring, maritime awareness, and other time-sensitive applications. |
| NSDI | National Spatial Data Infrastructure: A national framework of spatial data, standards, policies, technologies, and partnerships supporting coordinated geospatial information development, discovery, sharing, and use. |
| NTL | Nighttime Lights: Satellite observations of nocturnal illumination used to study settlement patterns, electrification, economic activity, and outages, with corrections needed for viewing and atmospheric effects. |
| O | |
| O&M | Observations and Measurements: A standardized conceptual model describing observations, measured properties, procedures, and features of interest, supporting interoperable exchange of sensor and environmental information. |
| OBIA | Object-Based Image Analysis: Image analysis that groups pixels into objects and uses their combined properties for classification, reducing reliance on individual pixel spectra. |
| OCO | Orbiting Carbon Observatory: A mission and instrument series measuring atmospheric carbon dioxide with high-precision spectroscopy to support carbon-cycle research and analysis of sources and sinks. |
| OD | Origin–Destination: A representation of movement between starting and ending locations, commonly organized into matrices or flows for mobility, accessibility, and spatial-network analysis. |
| OGC | Open Geospatial Consortium: An international standards organization developing specifications that enable geospatial data, services, sensors, and software to work together across platforms. |
| OLCI | Ocean and Land Colour Instrument: A Sentinel-3 imaging spectrometer providing observations for ocean color, water quality, vegetation, and other land and marine environmental products. |
| OLI | Operational Land Imager: The Landsat 8 reflective-band instrument, with a successor on Landsat 9, supplying calibrated multispectral imagery for land-cover and surface-change analysis. |
| OMI | Ozone Monitoring Instrument: An instrument aboard Aura measuring ultraviolet and visible radiation to retrieve ozone, trace gases, and aerosol information for atmospheric and air-quality studies. |
| OSAVI | Optimized Soil-Adjusted Vegetation Index: A vegetation index using a fixed soil-adjustment factor to reduce background effects, supporting canopy assessment where exposed soil influences spectral measurements. |
| OSGeo | Open Source Geospatial Foundation: A nonprofit foundation supporting open-source geospatial software, community development, and education, with projects widely used in mapping and imagery-processing infrastructure. |
| OSM | OpenStreetMap: A collaboratively maintained geographic database of roads, buildings, and other features, used as a basemap and analytical input subject to its data license. |
| OTB | Orfeo ToolBox: An open-source remote-sensing image-processing library offering tools for classification, segmentation, feature extraction, and large-image processing within automated workflows. |
| P | |
| PALSAR | Phased Array type L-band Synthetic Aperture Radar: A Japanese radar-instrument series providing longer-wavelength observations for forest monitoring, surface-change detection, terrain mapping, and deformation analysis. |
| PAN | Panchromatic: A broad spectral imaging band commonly acquired at finer spatial resolution than companion multispectral bands, supporting detailed interpretation and pan-sharpening. |
| PCA | Principal Component Analysis: A transformation reducing correlated spectral bands into orthogonal components, used in remote sensing for dimensionality reduction, information enhancement, and change analysis. |
| PDAL | Point Data Abstraction Library: An open-source library and processing framework for point-cloud data, supporting format conversion, filtering, classification, and automated elevation-data workflows. |
| PDOP | Position Dilution of Precision: A satellite-geometry factor describing amplification of ranging errors into three-dimensional position uncertainty, used to assess survey conditions and acquisition quality. |
| PIF | Pseudo-Invariant Feature: A surface feature assumed to have stable reflectance across acquisitions, used as a reference for relative radiometric normalization of multitemporal imagery. |
| POI | Point of Interest: A geolocated place or feature with descriptive attributes, used in location intelligence, accessibility analysis, asset mapping, and enrichment of geographic datasets. |
| PolInSAR | Polarimetric Interferometric Synthetic Aperture Radar: A technique combining radar polarization and interferometry to characterize vertical scattering structure, particularly for forest-height estimation and vegetation analysis. |
| PolSAR | Polarimetric Synthetic Aperture Radar: Radar imaging that uses multiple polarization channels to characterize scattering mechanisms, improving discrimination of vegetation, built structures, soil, and water. |
| PPP | Precise Point Positioning: A positioning technique using precise satellite orbit and clock products with a single receiver, avoiding reliance on a nearby local reference station. |
| PS | Persistent Scatterer: A radar target maintaining sufficiently stable phase behavior across repeated acquisitions, enabling reliable deformation measurements in multitemporal interferometric analysis. |
| PSF | Point Spread Function: The image response to an ideal point source, describing spatial blur and supporting sensor characterization, image restoration, and cross-sensor resolution matching. |
| PSI | Persistent Scatterer Interferometry: A multitemporal radar technique estimating displacement at stable scattering targets, widely applied to urban subsidence, infrastructure movement, and slope monitoring. |
| Q | |
| QPE | Quantitative Precipitation Estimation: The estimation of precipitation amounts from satellite, radar, gauge, or combined observations, supporting flood assessment, hydrology, and water-resource monitoring. |
| R | |
| RADAR | Radio Detection and Ranging: Active sensing that transmits radio waves and measures returning signals to determine range and scattering properties, enabling observations independent of daylight. |
| RADD | Radar for Detecting Deforestation: A radar-based forest-disturbance alert system using repeated Sentinel-1 observations to identify changes despite cloud cover in monitored tropical forests. |
| RASR | Range Ambiguity-to-Signal Ratio: A radar quality metric comparing ambiguous returns from other ranges with the desired signal, helping evaluate image contamination and acquisition-mode performance. |
| RCMC | Range Cell Migration Correction: A radar-focusing step compensating for a target’s changing apparent range during aperture synthesis, preventing energy from spreading across range cells. |
| RDA | Range-Doppler Algorithm: A synthetic-aperture radar processing method that focuses raw observations using range and Doppler-domain operations to form an interpretable image. |
| RFM | Rational Function Model: A mathematical model relating ground coordinates to image coordinates through ratios of polynomials, enabling satellite-image positioning without a complete physical sensor model. |
| RINEX | Receiver Independent Exchange Format: A standardized format for satellite-navigation observations and related information, allowing survey and geodetic processing across receiver manufacturers and software systems. |
| RMSE | Root Mean Square Error: A measure of differences between estimates and reference values, used to report positional, elevation, and retrieval accuracy while giving greater weight to larger errors. |
| ROI | Region of Interest: A selected image region or set of pixels used to sample spectra, train classifiers, inspect features, or evaluate image-processing results. |
| RPAS | Remotely Piloted Aircraft System: A remotely piloted aircraft together with its control station and associated components, used for aerial imagery and laser-scanning acquisition under applicable aviation rules. |
| RPC | Rational Polynomial Coefficients: Coefficients supplied with imagery to approximate its geometric sensor model, supporting orthorectification, stereo reconstruction, and conversion between image and ground coordinates. |
| RS | Remote Sensing: Obtaining information about objects or areas without direct contact, typically by measuring reflected or emitted electromagnetic energy from airborne or spaceborne platforms. |
| RTC | Radiometric Terrain Correction: Processing that normalizes radar backscatter for terrain-dependent illuminated area using an elevation model, improving comparability across slopes and observation geometries. |
| RTK | Real-Time Kinematic: A carrier-phase satellite-positioning technique using reference corrections to achieve high precision in real time, supporting surveying and direct georeferencing of aerial acquisitions. |
| RTM | Radiative Transfer Model: A model describing radiation absorption, emission, and scattering through media, used for atmospheric correction, sensor simulation, and retrieval of surface or atmospheric properties. |
| RVI | Radar Vegetation Index: A polarization-based radar indicator of vegetation scattering, used for crop and canopy monitoring with formulations matched to the available polarization channels. |
| RVI | Ratio Vegetation Index: The ratio of near-infrared to red reflectance, used to assess vegetation condition and biomass while remaining sensitive to soil background and canopy saturation. |
| S | |
| SAM | Spectral Angle Mapper: A classification method comparing the angle between pixel spectra and reference spectra, emphasizing spectral shape when identifying materials in multispectral or hyperspectral imagery. |
| SAR | Synthetic Aperture Radar: An imaging radar technique using platform motion to synthesize a large antenna aperture, producing detailed observations through clouds and without daylight. |
| SAVI | Soil-Adjusted Vegetation Index: A red and near-infrared vegetation index incorporating a soil-brightness adjustment, improving interpretation where exposed soil contributes substantially to pixel reflectance. |
| SBAS | Satellite-Based Augmentation System: A system broadcasting navigation corrections and integrity information through satellites to improve the accuracy and reliability of supported positioning services. |
| SBAS | Small Baseline Subset: An interferometric time-series method selecting radar image pairs with limited spatial and temporal separation to estimate deformation while reducing decorrelation. |
| SDI | Spatial Data Infrastructure: The technologies, standards, policies, and institutional arrangements enabling geospatial data discovery, access, sharing, and reuse across participating organizations. |
| SensorML | Sensor Model Language: An Open Geospatial Consortium standard describing sensors and measurement processes, supporting sensor discovery, observation interpretation, and processing-chain documentation. |
| SFA | Simple Feature Access: An Open Geospatial Consortium standard defining common vector geometry types and access conventions, supporting interoperable storage and querying of spatial features. |
| SfM | Structure from Motion: A photogrammetric approach estimating camera positions and three-dimensional scene structure from overlapping images, widely used in drone mapping and surface reconstruction. |
| SIF | Solar-Induced Fluorescence: Weak light emitted by chlorophyll following solar excitation, retrieved from spectral observations to investigate photosynthetic activity and ecosystem productivity. |
| SLC | Single Look Complex: A focused radar product retaining amplitude and phase in slant-range geometry, essential for interferometry and other analyses requiring complex signal information. |
| SLR | Satellite Laser Ranging: Precise distance measurement using laser pulses reflected by satellite targets, supporting orbit determination, gravity studies, and terrestrial reference-frame maintenance. |
| SLSTR | Sea and Land Surface Temperature Radiometer: A Sentinel-3 instrument providing thermal and reflective observations for sea-surface temperature, land-surface temperature, fire detection, and climate monitoring. |
| SMA | Spectral Mixture Analysis: A method estimating the proportions of reference materials contributing to a mixed pixel, supporting fractional mapping of vegetation, soil, shade, and other components. |
| SMAP | Soil Moisture Active Passive: A satellite mission providing global soil-moisture and freeze–thaw observations for drought monitoring, hydrology, agriculture, and land-surface modeling. |
| SMOS | Soil Moisture and Ocean Salinity: A European satellite mission using passive microwave observations to estimate soil moisture and sea-surface salinity for water-cycle and climate applications. |
| SNAP | Sentinel Application Platform: An open-source processing platform developed with European Space Agency support for working with Sentinel and other Earth-observation mission data. |
| SOS | Sensor Observation Service: An Open Geospatial Consortium standard for requesting sensor observations and associated metadata, enabling interoperable access to measurement streams and time-series data. |
| SPOT | Satellite Pour l’Observation de la Terre: A French-origin optical Earth-observation satellite series providing imagery used in mapping, land monitoring, stereo elevation production, and historical change analysis. |
| SRID | Spatial Reference Identifier: An identifier associating a geometry or dataset with a spatial reference definition, helping spatial databases interpret coordinates and perform appropriate transformations. |
| SRTM | Shuttle Radar Topography Mission: A radar-interferometry mission that produced widely used near-global elevation datasets, supporting terrain analysis, orthorectification, and hydrologic modeling. |
| SSO | Sun-Synchronous Orbit: An orbit maintaining approximately consistent local solar time at a given ground crossing, helping optical observations achieve comparable illumination across repeated acquisitions. |
| SST | Sea Surface Temperature: Ocean-surface temperature estimated from infrared or microwave observations, used in weather prediction, marine monitoring, climate analysis, and ocean-model validation. |
| STAC | SpatioTemporal Asset Catalog: A specification for describing and discovering geospatial assets by location, time, and metadata, enabling consistent search across imagery and other observation catalogs. |
| SWIR | Shortwave Infrared: An infrared spectral region sensitive to moisture and mineral absorption features, used in vegetation-water assessment, burn mapping, geology, and cloud discrimination. |
| SWOT | Surface Water and Ocean Topography: A satellite mission measuring water-surface elevations across oceans and inland waters, supporting hydrology, ocean circulation studies, and freshwater monitoring. |
| T | |
| TCC | Tree Canopy Cover: The proportion of ground area covered by tree crowns, mapped from imagery or laser observations for forestry, urban greening, and habitat analysis. |
| TDI | Time Delay and Integration: An imaging technique accumulating signal across detector stages synchronized with scene motion, improving sensitivity in moving-platform line-scanning cameras. |
| TIN | Triangulated Irregular Network: A surface model formed from connected, non-overlapping triangles, allowing variable point density and explicit terrain features in elevation and engineering analysis. |
| TIR | Thermal Infrared: Infrared wavelengths used to observe emitted radiation from Earth’s surface and atmosphere, supporting temperature retrieval, heat mapping, and energy-balance analysis. |
| TIRS | Thermal Infrared Sensor: The Landsat 8 thermal instrument, with a successor on Landsat 9, providing measurements used to estimate land-surface temperature and evapotranspiration. |
| TM | Thematic Mapper: A multispectral instrument flown on Landsat 4 and 5, whose visible, infrared, and thermal observations underpin decades of land-change analysis. |
| TOA | Top of Atmosphere: The reference level for radiance or reflectance observed above the atmosphere. Such measurements retain atmospheric influences unless additional correction is applied. |
| TPW | Total Precipitable Water: The equivalent water depth obtained by condensing all water vapor in an atmospheric column, used in weather analysis and atmospheric-correction workflows. |
| TRMM | Tropical Rainfall Measuring Mission: A satellite mission whose radar and radiometer observations established a major tropical-precipitation record, supporting hydrology, climate research, and subsequent rainfall products. |
| TROPOMI | Tropospheric Monitoring Instrument: The Sentinel-5 Precursor spectrometer retrieving atmospheric trace gases and aerosols for air-quality monitoring, emissions analysis, and atmospheric research. |
| U | |
| UAS | Unmanned Aircraft System: An aircraft without an onboard pilot together with its control and support components, used for localized aerial mapping, inspection, and environmental data collection. |
| UAV | Unmanned Aerial Vehicle: The aircraft component of an unmanned system, carrying cameras, multispectral sensors, thermal imagers, or laser scanners for aerial geospatial acquisition. |
| UMM | Unified Metadata Model: A metadata framework used in the United States civilian Earth-science data ecosystem to describe collections, granules, services, and related resources consistently. |
| UN-GGIM | United Nations Committee of Experts on Global Geospatial Information Management: A United Nations expert body advancing national geospatial capabilities, international coordination, and frameworks for integrating geospatial information into public decision-making. |
| UPS | Universal Polar Stereographic: A coordinate system using polar stereographic projections for regions beyond the usual transverse Mercator latitude limits, supporting consistent polar mapping. |
| USGS | United States Geological Survey: A United States science agency managing major geospatial resources, including Landsat data, national elevation information, hydrography, and land-cover products. |
| UTM | Universal Transverse Mercator: A projected coordinate system dividing most of Earth into six-degree longitude zones, providing meter-based coordinates for regional mapping and spatial analysis. |
| V | |
| VGI | Volunteered Geographic Information: Geographic information contributed by members of the public, expanding mapping coverage while requiring attention to completeness, positional accuracy, provenance, and contributor bias. |
| VHR | Very High Resolution: An imagery category commonly associated with spatial detail of a few meters or finer, supporting detailed mapping of buildings, infrastructure, and small features. |
| VI | Vegetation Index: A mathematical combination of spectral measurements designed to emphasize vegetation properties, used to monitor greenness, moisture, canopy condition, or productivity. |
| VIIRS | Visible Infrared Imaging Radiometer Suite: A polar-orbiting imaging instrument providing observations for clouds, fires, vegetation, ocean properties, surface temperature, and nighttime-light products. |
| VLM | Vertical Land Motion: Upward or downward movement of Earth’s surface, measured through geodetic and remote-sensing methods to assess subsidence, uplift, and relative sea-level change. |
| VRT | Virtual Raster: A lightweight dataset description referencing existing raster files and processing instructions, enabling mosaics and derived views without duplicating underlying image data. |
| W | |
| WAAS | Wide Area Augmentation System: A United States satellite-based navigation augmentation system providing corrections and integrity information, improving positioning for compatible receivers used in field mapping. |
| WCS | Web Coverage Service: An Open Geospatial Consortium standard for accessing coverage data, such as raster measurements, while retaining values needed for analysis rather than only visualization. |
| WFS | Web Feature Service: An Open Geospatial Consortium standard for accessing geographic features and their attributes over the web, enabling vector-data exchange rather than rendered-map delivery. |
| WGS 84 | World Geodetic System 1984: A global geodetic reference system underlying the United States satellite-navigation system and widely used geographic coordinates, with realizations relevant to precise positioning. |
| WKB | Well-Known Binary: A standardized binary representation of vector geometries, used to exchange spatial objects efficiently between databases, software libraries, and processing systems. |
| WKT | Well-Known Text: In coordinate referencing, a structured text representation describing coordinate reference systems and coordinate operations, supporting explicit exchange of spatial-reference definitions. |
| WKT | Well-Known Text: In geometry exchange, a readable text representation of points, lines, polygons, and related geometric objects, commonly used in spatial databases and debugging. |
| WMS | Web Map Service: An Open Geospatial Consortium standard for requesting georeferenced map images, allowing distributed spatial layers to be displayed together without transferring their underlying datasets. |
| WMTS | Web Map Tile Service: An Open Geospatial Consortium standard serving predefined map tiles at specified scales, supporting efficient delivery and caching of basemaps and imagery visualizations. |
| WPS | Web Processing Service: An Open Geospatial Consortium standard for describing and executing geospatial processing operations remotely, supporting interoperable analytical services and workflows. |
| WRS | Worldwide Reference System: The path-and-row geographic indexing framework used to identify Landsat scenes, simplifying imagery search, acquisition planning, and consistent archive organization. |