Posted on July 20, 2022 in Help

Routescene’s dictionary to demystify UAV LiDAR

To help you understand UAV LiDAR and data processing language, here’s a glossary of commonly used geospatial, UAV survey, LiDAR and data processing terms.

Geospatial phrases and acronyms

SurveyA land survey, or simply survey, is the scientific process of measuring the dimensions of a particular area of the earth's surface, including its horizontal distances, directions, angles, and elevations.
Survey planningSurvey planning is undertaken in advance of a survey to capture the
survey objectives, timings, the survey area, permissions needed, quality level and the deliverables required. How the data acquisition will be undertaken, logistics, health & safety and any training should also be included.
Quality Assurance (QA)Quality Assurance is a holistic approach to conducting business. It includes policies and systems designed to ensure that quality standards and processes are adhered to and that the final product meets or exceeds the required technical and performance requirements.
Quality Control (QC)Quality Control focuses on the product or service. A set of QC procedures is used to ensure the desired level of quality is achieved and to assess what changes may be needed if it is not achieved.
Geographic Information System (GIS)A geographic information system (GIS) is a system that creates, manages, analyzes, and maps geographically referenced data. GIS connects data to a map, integrating location data (where things are) with all types of descriptive information (what things are like there).
Global Navigation Satellite System (GNSS)Refers to a constellation of satellites providing signals from space that transmit positioning and timing data to GNSS receivers.
Real Time Kinematic (RTK)Technique used in real time to enhance the precision of position data using carrier-based ranging.
Post-Processed Kinematic (PPK)Technique used in post-processing to enhance the precision of position data using carrier-based ranging.
GeoreferenceGeoreferencing means that the internal coordinate system of a digital map or aerial photo can be related to a ground system of geographic coordinates.
Datum or GeodeticReference from which spatial measurements are made.

LiDAR phrases and acronyms

Light Detection and Ranging (LiDAR)Is a remote sensing method used to examine the surface of the Earth. LiDAR uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth.
LiDAR sensor or scannerThis is an instrument using LiDAR technology. LiDAR sensors are typically integrated into larger systems containing other types of sensors. The data collected can be combined to generate precise, three-dimensional information about the shape of the Earth and its surface characteristics.
LiDAR frameData from one complete 360 degrees rotation of a mechanical LiDAR sensor.

Data from one single emission of the laser(s) from a solid state LiDAR sensor.
Laser IDEach LiDAR sensor has a set number of lasers e.g. 1, 16 or 32 lasers.
Each laser has a laser number or ID.

UAV LiDAR phrases and acronyms

LiDAR post-processing softwareSpecialist software to clean, edit and analyse a point cloud in order to generate meaningful geospatial outputs.
Point cloudA set of data points in space. The points may represent a 3D shape or object. Each point has an x, y and z coordinate relative to the LiDAR sensor or referenced to the Earth if the point cloud has been georeferenced. Point clouds are typically produced by LiDAR sensors or photogrammetry software. Point clouds can be used for many purposes including creating 3D Digital Terrain Models or Digital Surface Models.
DatasetThis is another term for a “point cloud”, it is a collection of 3D points collected by a LiDAR sensor.
Raw dataThis refers to the LiDAR point cloud before any processing has occurred.
Processing and post-processingCollected LiDAR data needs to be processed to check the quality of the data and post-processed to create the required outputs such as a Digital Terrain Model (DTM).
DeliverablesA set of results or final outputs required by the end user or customer.
pcap fileContains data packets captured from a network. Several LiDAR scanners transmit all sensor data over Ethernet which is then captured as a pcap file.
Comma Separated Values file (csv)Plain text file that contains a list of data.
RasterMatrix of cells where each cell contains a value representing certain information.
GeoTIFFRaster image file type with georeferencing information embedded.
Las/laz filesIndustry standard for point cloud data files. The laz is a compressed format.
Ground Control Points (GCP)Places on the ground with precise known coordinates used to adjust the surveyed data. These must be at least two times more accurate than the data they intend to adjust.
Survey checkpointsPlaces on the ground with precise known coordinates used to validate the accuracy of the survey.
Boresight alignmentCorrection for the angular misalignment between the measurement axes of a laser scanning device and the measurement axes of an Inertial Measurement Unit (IMU).
Strip alignmentCorrection of horizontal and vertical displacements of points collected from different flight lines.
Ground pointsThe points on the point cloud that represent the ground.
Digital Terrain Model (DTM)Topographic or representation model of the ground surface.
Digital Surface Model (DSM)Topographic or representation model of the Earth's surface, including natural and man made objects located on it.
Canopy Height Model (CHM)Height between the ground and the top of objects above the ground. It is the difference between the DSM and DTM.
Track dataAlso known as Track or trajectory, the track data is collected by the Inertial Navigation System in your LiDAR system. This data contains information regarding the position of the LiDAR system, its movement and orientation.
Flight lineA predefined route, typically between two waypoints, along which the UAV has flown during the survey. Typically there are multiple flight lines undertaken per survey.
WaypointPhysical intermediate location on a flight where the aircraft stops or changes its direction. Waypoints are usually pre-determined during flight planning.
WorkflowA sequence of tasks that processes a dataset. Typically different workflows achieve different outputs.
LayerGeographical databases containing points, lines, polygons or raster images and their attributes.
ImageAn image is a picture that has been created or copied and stored in electronic form. An image can be described in terms of vector graphics or raster graphics.
VectorAn object that has both a magnitude and a direction. A vector can be represented by a line with an arrow pointing towards its direction and its length represents the magnitude of the vector.
OrthophotoAn aerial image that has been geometrically corrected or ortho rectified so that the image is uniform from edge to edge.
ExportTo convert a file into another format than the one it is currently in, typically to use it in another software application.