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GPS Surveying & Drone Mapping Glossary

By Antonio Liska • April 20, 2022 • Updated September 22, 2025

A comprehensive glossary of terms used in GPS, GNSS, surveying, and drone mapping solutions.

A

1. Aerotriangulation – A photogrammetric method of determining the geometric properties of objects from photographic images, especially for mapping and modeling purposes.
2. Ambiguity Resolution – The process of resolving integer ambiguities in GNSS signals, critical for precise RTK.
3. Antenna Phase Center – The point in an antenna where the GNSS signal is considered to be received, crucial for precise positioning calculations.
4. As-Built Survey – A survey that documents the final built state of a construction project for verification.

B

1. Base Station – A GNSS antenna and receiver set up as a reference to collect data for precise rover positioning.
2. Baseline – In GNSS surveying, the vector distance between two GNSS receivers tracking the same satellites.
3. BeiDou – A global navigation satellite system developed and operated by China.
4. BIM (Building Information Modeling) – A process involving digital representations of physical site characteristics.
5. BIMs (Building Information Models) – Digital models that support decision-making about built assets.
6. Boundary Survey – A survey establishing property lines and legal land boundaries.

C

1. CAD (Computer-Aided Design) – The use of computers in the creation and modification of 3D designs.
2. Carrier Phase – GNSS measurement method using the carrier signal wave for centimeter-level accuracy.
3. Cloud Point (Point Cloud) – A set of spatial data points representing surfaces, captured by 3D scanners or photogrammetry.
4. Control Network – A set of known control points used to align and georeference survey data.
5. Control Point – A known point on the ground used to georeference and align spatial data.
6. CORS (Continuously Operating Reference Stations) – Networks of GNSS receivers providing real-time correction data.
7. Correction Data – Data used to improve GNSS accuracy by correcting atmospheric, orbit, and clock errors.

D

1. DEM (Digital Elevation Model) – A 3D representation of terrain excluding objects like buildings and vegetation.
2. Differential GPS (DGPS) – A positioning method using a reference station to correct GPS signals.
3. Digital Twin – A virtual representation of a physical site or asset, built from mapping and BIM data.
4. DOP (Dilution of Precision) – Indicator of GNSS positional quality based on satellite geometry.
5. DSM (Digital Surface Model) – A 3D surface model including natural and built objects.
6. DTM (Digital Terrain Model) – A detailed terrain model including break lines and mass points.

E

1. ECEF (Earth-Centered, Earth-Fixed) – A Cartesian coordinate system used in geodesy.
2. EGNOS (European Geostationary Navigation Overlay Service) – A European satellite-based augmentation system.
3. Ellipsoid – A mathematical model approximating the Earth’s shape.
4. Ephemeris Data – Information about satellite positions and velocities used by GNSS receivers.

F

1. Fixed Solution – An RTK GPS solution where ambiguities are resolved, yielding highest precision.
2. Float Solution – An RTK GPS solution where ambiguities remain unresolved, less accurate than fixed.
3. Flight Planning Software – Tools used to design automated UAV mapping missions.

G

1. Galileo – A GNSS system operated by the European Union.
2. GCP (Ground Control Point) – A known reference point for surveying and photogrammetry.
3. Geocoding – Converting addresses into geographic coordinates.
4. Geodatabase – A database designed to store and manage spatial data.
5. Geodetic Datum – A coordinate reference system used in mapping.
6. Geoid – The hypothetical sea-level surface used to measure elevations.
7. Georeferencing – Assigning real-world coordinates to spatial data.
8. GIS (Geographic Information System) – A system for analyzing and displaying geospatial data.
9. GLONASS – The GNSS operated by Russia.
10. GNSS (Global Navigation Satellite System) – The umbrella term for satellite-based navigation systems.
11. GPS (Global Positioning System) – The GNSS operated by the U.S. government.
12. GSD (Ground Sampling Distance) – The ground distance represented by one image pixel.
13. Geospatial Analytics – The process of analyzing geographic and spatial data for insights.
14. Geospatial Data – Data tied to geographic coordinates used in GIS, mapping, and surveying.

H

1. HDOP (Horizontal Dilution of Precision) – The effect of satellite geometry on horizontal accuracy.

I

1. IMU (Inertial Measurement Unit) – A device that measures force, angular rate, and sometimes magnetic fields.
2. Integration SBAS vs GBAS – Satellite-based vs ground-based augmentation systems for GNSS accuracy.

K

1. Kinematic Surveying – A surveying method where the GNSS receiver is in motion.

L

1. L1 – The primary GPS frequency at 1575.42 MHz.
2. L2 – The secondary GPS frequency at 1227.6 MHz.
3. LiDAR (Light Detection and Ranging) – A remote sensing method using laser pulses to create 3D maps.

M

1. Map Projection – Transformation of Earth’s surface onto a flat plane.
2. Mesh Model – A 3D model created by connecting point cloud data into surfaces.
3. Multipath – GNSS error caused by signal reflection.

N

1. NAD83 (North American Datum 1983) – A geocentric datum used in North America.
2. NMEA – A standard data format for GNSS devices to transmit data.
3. NTRIP (Networked Transport of RTCM via Internet Protocol) – A protocol for transmitting GNSS corrections over the internet.

O

1. OPUS (Online Positioning User Service) – A U.S. service providing post-processed GPS positioning.
2. Orthoimage – A geometrically corrected aerial image with uniform scale.
3. Orthomosaic – A seamless aerial image composed of multiple stitched, corrected photos.

P

1. PDOP (Position Dilution of Precision) – Effect of satellite geometry on 3D position accuracy.
2. Photogrammetric Tie Point – Overlapping image points used to align photos in photogrammetry.
3. Photogrammetry – Making measurements from photos for mapping and modeling.
4. Point Cloud Classification – Sorting point cloud data into categories like ground, vegetation, and structures.
5. PPK (Post-Processed Kinematic) – A GNSS correction method applied after data collection.
6. PPP (Precise Point Positioning) – A high-accuracy GNSS method without local reference stations.
7. PPP-RTK – Hybrid correction technique combining PPP and RTK for global accuracy.
8. Precision – The repeatability of a set of measurements.

R

1. RDOP (Relative Dilution of Precision) – Positional error between two receivers.
2. RINEX (Receiver Independent Exchange Format) – A file format for raw GNSS data.
3. Rover – A mobile GNSS receiver used in surveying.
4. RTCM – A standard protocol for GNSS correction data exchange.
5. RTK (Real-Time Kinematic) – A GNSS technique providing centimeter-level accuracy in real time.
6. RTN (Real-Time Network) – A GNSS reference station network providing wide-area corrections.
7. Radiometric Calibration – Adjusting sensor data for accurate reflectance values in imagery.

S

1. Satellite Observation – A record of GNSS signals received for processing.
2. SBAS (Satellite-Based Augmentation System) – Improves GNSS accuracy via correction signals.
3. SBET (Smoothed Best Estimate of Trajectory) – Combined IMU and GNSS data for accurate positioning.
4. SfM (Structure from Motion) – Technique reconstructing 3D structures from 2D image sequences.
5. Signal-to-Noise Ratio (SNR) – GNSS signal quality compared to background noise.
6. Spatial Resolution – The detail level in raster imagery, often linked with GSD.
7. Static Surveying – GNSS surveying with a stationary receiver for high precision.
8. Survey Grade GPS – High-precision GNSS receivers capable of centimeter-level accuracy.
9. Surveying Solutions – Techniques and tools (GNSS, UAV, LiDAR) for land, construction, and resource surveys.

T

1. TDOP (Time Dilution of Precision) – Effect of satellite geometry on timing accuracy.
2. Thermal Mapping – UAV-based thermal imaging for monitoring heat signatures in agriculture, infrastructure, or environment.
3. Topographic Survey – A survey mapping land contours, elevations, and features.
4. Transformation – Converting coordinates from one system to another.
5. Tropospheric Delay – Delay in GNSS signals due to the Earth’s troposphere.

U

1. UAV (Unmanned Aerial Vehicle) – A drone used for aerial imaging and surveying.
2. UTM (Universal Transverse Mercator) – A global coordinate system dividing Earth into zones.

V

1. VDOP (Vertical Dilution of Precision) – The effect of satellite geometry on vertical position accuracy.
2. Vector Data – Geographic data represented as points, lines, or polygons.

W

1. WGS 84 (World Geodetic System 1984) – The reference ellipsoid used by GPS.
2. WMS (Web Map Service) – A standard protocol for serving map images online.