Understanding the technical terminology used in drone surveying, mapping, and inspection helps you make informed decisions about your project. This glossary defines commonly used terms across our service areas — from LiDAR and photogrammetry to thermal imaging, confined space inspections, and more.

A

Aerial Photography

The capture of photographs from a drone (UAV) airborne platform. Aerial photography provides high-resolution imagery of landscapes, structures, and terrain for mapping, inspection, marketing, and documentation. Drone-based aerial photography offers far greater resolution than satellite imagery and can be scheduled on demand.

B

Bare Earth Model

A digital elevation model (DEM) representing only the ground surface, with all above-ground features — buildings, trees, vehicles — removed through LiDAR classification. Bare earth models are critical for hydrological analysis, floodplain mapping, and engineering design where true terrain elevation is required.

BIM (Building Information Modeling)

A digital representation of the physical and functional characteristics of a building or infrastructure asset. Drone-collected LiDAR point clouds and photogrammetric models feed directly into BIM workflows for as-built documentation, renovation planning, and facilities management. BIM enables teams to collaborate on a shared 3D model throughout an asset’s lifecycle.

Breakline (Hard & Soft)

Lines used in terrain modeling to enforce accurate surface representation along features that interrupt smooth elevation gradients. A hard breakline defines a sharp change in slope — such as a road edge, stream bank, or building foundation. A soft breakline represents a gradual change in slope, such as a ridge or valley centerline.

C

Canopy Height Model (CHM)

A raster dataset representing the height of vegetation above the ground surface, calculated by subtracting the DTM from the DSM. CHMs are used in forestry management, habitat assessment, and agricultural monitoring to measure tree heights and map vegetation density across large areas.

Cartography

The science and art of creating maps. In drone services, cartography involves using aerial imagery and point cloud data to produce accurate, georeferenced maps of terrain, infrastructure, or land use. Drone-based cartography generates survey-quality maps far more quickly than traditional ground-based methods.

Classification (LiDAR Point Classification)

The process of categorizing individual points in a LiDAR point cloud based on what they represent — ground, low/medium/high vegetation, buildings, water, noise, and more. Classification is performed using automated algorithms and manual review, and is essential for generating bare earth models, canopy data, and building footprints from raw LiDAR.

Confined Space Inspection

The use of small, specialized drones to inspect enclosed or hard-to-access areas such as storage tanks, boilers, silos, tunnels, pipelines, and mines. Confined space drone inspections eliminate the need for workers to enter hazardous environments, dramatically reducing safety risk, inspection time, and cost. Skyflex deploys purpose-built inspection drones capable of navigating tight, GPS-denied environments.

Contour Map

A map using contour lines to represent elevation, with each line connecting points of equal height. Contour maps derived from LiDAR or photogrammetric data make it easy to visualize terrain shape, slope steepness, and watershed boundaries. They are fundamental tools in civil engineering, land development, and environmental planning.

D

DEM (Digital Elevation Model)

A general term for any digital representation of terrain elevation. DEMs can refer to bare-earth models (DTMs) or full surface models (DSMs) depending on context. They are produced from LiDAR or photogrammetry and serve as inputs for mapping, hydraulic modeling, solar analysis, and engineering design.

DGPS (Differential GPS)

A GPS enhancement technique using a fixed ground reference station to correct position errors in real time or post-processing. DGPS improves horizontal accuracy — often to sub-meter precision — making it valuable for survey-grade drone flights where spatial accuracy is critical.

Digital Twin

A highly accurate, data-rich 3D virtual replica of a physical asset, site, or environment created using drone-collected LiDAR, photogrammetry, or sensor fusion data. Digital twins enable facility owners to monitor, analyze, and simulate changes without physical access. They are used across infrastructure management, construction, manufacturing, energy, and smart city applications.

DSM (Digital Surface Model)

A digital elevation model capturing the elevation of all features on the earth’s surface — buildings, trees, power lines — above the ground. The DSM represents the topmost visible surface (the “first return” model), as opposed to the DTM which represents bare ground. DSMs are used in line-of-sight analysis, solar panel placement, and urban planning.

DTM (Digital Terrain Model)

A digital representation of the bare ground surface with above-ground objects removed, enhanced with additional terrain features such as breaklines, ridgelines, and stream centerlines. The DTM is more detailed and hydrologically accurate than a simple bare earth DEM, and is the preferred product for civil engineering, drainage design, and flood modeling.

F

FAA Part 107

The Federal Aviation Administration regulation governing commercial small unmanned aircraft system (sUAS) operations in the United States. Part 107 requires drone pilots to pass an aeronautical knowledge test, obtain an FAA Remote Pilot Certificate, and operate within defined airspace limitations. All Skyflex UAS pilots hold active FAA Part 107 certifications, ensuring safe and fully compliant operations.

Final Return

In LiDAR scanning, the last reflection recorded from a single laser pulse. When a pulse travels through vegetation, it may reflect off multiple surfaces (leaves, branches, ground) before its energy is fully absorbed. The final return most often represents the ground surface and is the primary data source for generating bare earth terrain models.

FLIR (Forward Looking Infrared)

A type of thermal imaging sensor that detects infrared radiation (heat) emitted by objects and converts it into a visible image. FLIR cameras mounted on drones identify heat signatures invisible to the naked eye — electrical faults, roof moisture intrusion, failed solar cells, heat loss in building envelopes. “FLIR” is widely used as a generic term for drone-mounted thermal cameras.

G

GCPs (Ground Control Points)

Precisely surveyed physical markers placed on the ground within a project area, whose coordinates are measured with high-accuracy GPS equipment. GCPs georeference drone imagery and LiDAR data to real-world coordinates, improving absolute positional accuracy. They are especially important for survey-grade photogrammetry projects requiring high horizontal and vertical accuracy.

GIS (Geographic Information System)

A computer system for capturing, storing, analyzing, and displaying spatial and geographic data. GIS platforms such as ArcGIS and QGIS integrate drone-collected datasets — orthomosaics, DEMs, point clouds — with other geographic information to support planning, analysis, and decision-making across civil engineering, environmental management, agriculture, and utilities.

GPS (Global Positioning System)

A satellite-based navigation system providing location and time information anywhere on Earth. Drones use GPS for flight stabilization, waypoint navigation, and georeferencing of collected data. Survey-grade GPS techniques such as RTK and PPK enable centimeter-level positioning accuracy essential for precision mapping and inspection.

Ground Sampling Distance (GSD)

The distance on the ground represented by a single pixel in an aerial image — the spatial resolution of drone-collected imagery. A smaller GSD means higher resolution: a GSD of 1 cm means each pixel covers 1 cm x 1 cm on the ground. GSD is determined by camera sensor size, focal length, and flight altitude, and directly affects the detail and measurement accuracy achievable from imagery.

H

Hillshade Map

A raster visualization simulating the appearance of terrain illuminated by directional sunlight, highlighting ridges, valleys, slopes, and surface textures. Hillshade maps are derived from DEMs and widely used for visual terrain interpretation, archaeological site discovery, and geomorphological analysis. They are often displayed semi-transparently beneath other map layers to add depth and context.

Hydrologically Flattened

A post-processing technique applied to digital terrain models to enforce realistic water flow behavior. Water bodies such as lakes and reservoirs are flattened to a consistent elevation, and stream networks are enforced into the DEM to ensure flow paths are continuous and uninterrupted. Hydrologically flattened DEMs are required for accurate stormwater modeling, floodplain delineation, and watershed analysis.

I

IMU (Inertial Measurement Unit)

An electronic sensor package measuring a drone’s acceleration, angular rate, and orientation in three dimensions. The IMU works in tandem with GPS to maintain stable flight and precisely record the position and attitude of the drone and its sensors at every moment of data collection. High-accuracy IMUs are critical for producing precise LiDAR point clouds and well-registered photogrammetric outputs.

Initial Return

The first reflection received from a single LiDAR laser pulse. When a pulse strikes the top of a tree canopy or a rooftop before reaching the ground, the initial return captures the elevation of that uppermost surface. Initial returns are used to generate Digital Surface Models (DSMs) and canopy height data.

Intensity Image

A grayscale image produced from LiDAR data, where pixel brightness represents the strength of each laser pulse return from that surface. Intensity images resemble aerial photographs and help identify surface materials, road markings, and vegetation types based on reflectivity. They are useful for visual interpretation of LiDAR datasets independent of optical imagery.

L

LiDAR (Light Detection and Ranging)

A remote sensing technology using pulsed laser light to measure distances and generate precise 3D representations of surfaces and objects. Mounted on drones, LiDAR sensors emit hundreds of thousands of laser pulses per second and record the time each pulse takes to return after striking a surface. The result is a dense three-dimensional point cloud accurately capturing terrain, vegetation, and structures — even through tree canopy gaps. LiDAR is widely used in surveying, engineering, environmental science, forestry, and infrastructure inspection.

M

Multiple Returns

The ability of advanced LiDAR systems to record more than one reflection from a single laser pulse. When a pulse passes through semi-transparent surfaces like tree branches or tall grass, it generates multiple returns at different distances — capturing both the vegetation canopy and the ground surface below. Multiple return capability is essential for generating accurate bare earth models in forested or heavily vegetated terrain.

N

NAICS Codes

North American Industry Classification System (NAICS) codes categorize businesses by their primary activities. Skyflex UAS operates across the following codes, reflecting the breadth of our drone service offerings:

541370 — Surveying & Mapping Services: Aerial LiDAR, photogrammetry, topographic mapping, and GIS data collection.

541922 — Commercial Photography (Aerial Imaging): Aerial photography, orthomosaic production, and drone video documentation.

541715 — R&D in Physical, Engineering & Life Sciences: Research and development in drone sensor integration, autonomous systems, and advanced aerial data collection methodologies.

561790 — Other Services to Buildings & Dwellings: Drone-based exterior cleaning services including solar panel washing, rooftop cleaning, and building facade maintenance.

NDVI (Normalized Difference Vegetation Index)

A numerical index calculated from near-infrared (NIR) and red light reflectance data that quantifies vegetation health and density. NDVI values range from -1 to +1, with higher values indicating healthy, dense vegetation and lower values indicating stressed or absent plant matter. Drone-mounted multispectral cameras capture the data needed to generate NDVI maps for precision agriculture, environmental monitoring, and land management.

O

Orthophoto / Orthomosaic

A geometrically corrected aerial image — or mosaic of many overlapping images — in which perspective distortion and terrain relief displacement have been removed, giving it the uniform scale of a map. Unlike regular photographs, orthomosaics can be used to accurately measure distances, areas, and positions. Drone-generated orthomosaics are produced through photogrammetry processing and are used extensively in engineering, construction, agriculture, and land planning.

P

Photogrammetry

The science of extracting precise measurements and 3D models from overlapping photographs. Drone photogrammetry involves capturing images with high overlap while flying a systematic grid pattern, then processing those images through Structure from Motion (SfM) software to produce point clouds, digital elevation models, orthomosaics, and 3D textured models. Photogrammetry is a cost-effective complement or alternative to LiDAR for many mapping applications.

Point Cloud

A large dataset of individual 3D points — each with X, Y, and Z coordinates — representing the geometry of a surface or object. LiDAR point clouds are generated from laser pulse returns; photogrammetric point clouds are derived from overlapping images via SfM processing. Point clouds are the foundational raw dataset from which DEMs, 3D meshes, orthomosaics, and other deliverables are produced. They are typically delivered in .LAS or .LAZ file format.

PPK (Post-Processed Kinematic)

A GPS accuracy enhancement method in which raw positioning data from both the drone and a fixed reference station are recorded during flight and combined afterward in software to achieve centimeter-level positional accuracy. Unlike RTK (which corrects in real time), PPK works even if the link between drone and base station is interrupted during the mission. PPK is widely used for precision mapping and survey-grade aerial data collection.

Pulse (LiDAR)

A single burst of laser energy emitted by a LiDAR sensor toward a target surface. Each pulse travels at the speed of light and generates one or more returns when it reflects off surfaces in its path. Modern airborne LiDAR systems emit hundreds of thousands to millions of pulses per second, enabling rapid collection of dense 3D point data over large project areas.

Pulses per Square Meter

A measure of LiDAR point density indicating how many laser pulses strike each square meter of the surveyed area. Higher pulse density yields more detailed and accurate point clouds. Required density varies by application — high-density collection (8–20+ pulses/m²) suits corridor mapping or forest analysis, while lower density (1–4 pulses/m²) may suffice for broad-area terrain mapping.

R

Return (LiDAR)

A single reflection of a LiDAR laser pulse recorded by the sensor receiver. A single emitted pulse may generate multiple returns if it passes through partially transparent surfaces before reaching the ground. Each return is recorded with its own XYZ position and intensity value, contributing to the overall point cloud dataset.

RTK (Real-Time Kinematic)

A GPS accuracy enhancement technique using a fixed ground base station to transmit real-time positional corrections to a rover — such as a drone — achieving centimeter-level accuracy during flight. RTK eliminates or greatly reduces the need for ground control points (GCPs) in mapping projects, streamlining field workflows. RTK requires a maintained radio or cellular communication link between the base station and drone throughout the mission.

S

SLAM LiDAR (Simultaneous Localization and Mapping)

A ground-based scanning approach in which a handheld, backpack-mounted, or mobile LiDAR system builds a 3D map of its environment while simultaneously tracking its own position — without requiring GPS. SLAM LiDAR excels in GPS-denied environments such as building interiors, underground tunnels, mines, parking structures, and dense forest understory where aerial drones cannot safely operate. SLAM-collected point clouds can be merged with aerial LiDAR data to produce complete, seamless 3D models of complex multi-level sites.

Slope Map

A derived raster dataset displaying terrain steepness at each location, calculated from a digital elevation model. Slope values are expressed in degrees or percent grade and are used in erosion assessment, landslide hazard mapping, road and pipeline route planning, agricultural drainage analysis, and construction site feasibility studies.

Structure from Motion (SfM)

A photogrammetric computation technique that reconstructs 3D structure from a series of 2D images captured from multiple overlapping viewpoints. SfM algorithms identify and match common features across drone images, then simultaneously compute camera positions and 3D point positions. SfM is the core computational method behind modern drone photogrammetry, implemented in platforms such as Agisoft Metashape, Pix4D, and DroneDeploy.

T

Thermal Imaging

The use of infrared sensors to detect and visualize heat emitted by objects, surfaces, or systems. Thermal cameras mounted on drones reveal temperature differences invisible to the naked eye, enabling applications including solar panel inspection, roof moisture surveys, electrical fault detection, building energy audits, search and rescue support, wildlife surveys, and crop stress mapping. Thermal data is displayed as a false-color image where color represents temperature.

TIN (Triangulated Irregular Network)

A vector-based method of representing terrain using a network of non-overlapping triangles formed between irregularly spaced elevation points. TINs preserve important terrain features like breaklines and mass points while using fewer data points to represent flat or uniform areas. They are commonly used in civil engineering design, hydrological modeling, and 3D terrain visualization.

U

UAS / UAV (Unmanned Aircraft System / Unmanned Aerial Vehicle)

A UAV (drone) is an aircraft that operates without a pilot on board, controlled remotely or through autonomous flight. A UAS encompasses the complete system — the aircraft, ground control station, communications links, and any sensors or payloads. Commercial UAS platforms range from compact quadcopters used for inspection and photography to fixed-wing aircraft suited for large-area mapping missions.

V

Vector Data

Spatial data represented as discrete geometric features — points, lines, and polygons — each associated with descriptive attribute information. In GIS and mapping, vector data represents features such as property boundaries, roads, utility lines, building footprints, and stream networks. Drone-collected LiDAR and imagery can be processed to extract vector features through automated classification or manual digitizing by GIS analysts.