Glossary of Terms

Glossary of Bathymetric Lidar Terms

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This page provides definitions and explanations for terms commonly used in the context of bathymetric lidar and related technologies.

| A-E | F-J | K-O | P-T | U-Z |

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A-E

Altimetry

*The measurement of altitude or height. In bathymetric lidar, altimetry refers to the measurement of the water surface elevation.*

Bathymetry

*The study and mapping of seafloor topography. Bathymetric lidar is used to measure depths and map underwater features.*

Beam Divergence

*The gradual spreading out of the laser beam as it travels away from the source, typically measured in milliradians (mrad).*

Calibration

*The process of adjusting and setting a measurement instrument to ensure its accuracy.*

Cross-track

*The direction perpendicular to the flight path of the lidar sensor. Cross-track measurements help in creating a complete map of the surveyed area.*

F-J

Field of View (FOV)

*The extent of the observable area that the sensor can capture at any given moment, typically measured in degrees (°).*

Footprint

*The area on the ground illuminated by the laser beam, often measured in meters or centimeters.*

Georeferencing

*The process of aligning spatial data (e.g., lidar data) to a known coordinate system so it can be accurately mapped.*

GNSS (Global Navigation Satellite System)

*A satellite-based navigation system used to determine precise location data, critical for accurate georeferencing of bathymetric lidar data.*

Horizontal Accuracy

*The degree of accuracy in the horizontal position of a point, typically measured in meters (m).*

K-O

Laser Energy Per Pulse

*The amount of energy emitted in each laser pulse, usually measured in millijoules (mJ).*

Laser Wavelength

*The distance between successive peaks of the electromagnetic waves of the laser, typically measured in nanometers (nm). Commonly used wavelengths for bathymetric lidar are in the visible green domain (e.g., 532 nm).*

Monte Carlo Simulation

*A computational algorithm that uses random sampling to obtain numerical results, often used to assess uncertainty.*

Multi-beam Lidar

*A lidar system that uses multiple laser beams to capture more data points simultaneously, improving coverage and resolution.*

Multispectral Lidar

*A lidar system capable of capturing data at different wavelengths, providing additional information about the surveyed area.*

Nominal Pulse Density

*The average number of laser pulses per square meter, indicating the resolution of the lidar data.*

P-T

Peak Measurement Frequency

*The maximum number of measurements the sensor can make per second, usually measured in kilohertz (kHz).*

Pulse Duration

*The length of time that each laser pulse lasts, typically measured in nanoseconds (ns).*

Range

*The distance between the lidar sensor and the target surface, calculated using the time delay of the reflected laser pulse.*

Resolution

*The smallest discernible detail in the data, determined by the sensor's capabilities and the density of data points.*

Swath Width

*The width of the area covered by the sensor in a single pass, measured in meters (m).*

Typical Bathymetric Point Spacings

*The average distance between individual measurement points on the seafloor, measured in meters (m).*

U-Z

Underwater Topography

*The study and mapping of the underwater surface, including features such as seafloor, riverbeds, and lake bottoms.*

Unmanned Aerial Vehicle (UAV)

*An aircraft piloted by remote control or onboard computers, often used for aerial lidar surveys.*

VDatum

*A software tool for converting geospatial data among different vertical datums.*

Vertical Accuracy

*The degree of accuracy in the vertical measurement of the seafloor, typically measured in centimeters (cm) or meters (m).*

Waveform

*The shape of the laser pulse as it is emitted and received, providing detailed information about the reflecting surfaces.*

Weight

*The total weight of the sensor system, measured in kilograms (kg).*