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DTA Drone & MAST Survey Inspection Photography & Video Services - for the whole of the UK



As with all technology industries, the drone industry uses a vast number of terms and terminology that to the uninitiated can simply be gobbledygook.

In this Drone Tech Aerospace Glossary of Terms resource page we attempt to explain many of these acronyms and terms in order to aid clients and business partners to understand and navigate this new drone industry.


Drone & Robotic Vehicles

There are many terms (typically three letter acronyms, TLAs) that are used interchangeably to refer to aerial, terrestrial and aquatic drones.


Automated Underwater Vehicle.
A remote controlled submersible aquatic drone.


An unmanned vehicle capable of programmed/software controlled or autonomous operation.
Strictly speaking this can be a terrestrial, aerial or aquatic remote-controlled system, although this is now increasingly a term accepted to mean an aerial system.


UAV with 4 rotors/propellers.

Hexa-copter / Hex-Drone

UAV with 6 rotors/propellers.


UAV with 8 rotors/propellers.


Generic term for a UAV with multiple rotors/propellers.
Includes quad, hex and octocopters etc.


Remotely Operated Vehicle.
As with the term drone, this can be a terrestrial, aerial or aquatic remote-controlled system.
Most typically this term is used for terrestrial or aquatic robotic vehicles.
The term "rover" was made fashionable way back during the NASA lunar landings, when a lunar rover manned vehicle was landed on the moon to enable NASA astronauts to explore wider areas during their brief time on the moon. The term is now used widely to denote a remotely controlled terrestrial vehicle.
ROV is a term now most typically used for aquatic submarine ROV's.


Remotely Piloted Aerial System (RPAS).
Another term for Aerial drone / UAV / UAS, but more specifically equivalent to UAS as it encompasses the whole system.

A term that is favoured by aviation authorities and often appears in regulatory and legal documents.


An Unmanned Aerial Vehicle (UAV).
A device that can propel itself through the air without a pilot onboard. Aerial drones, quadcopters and any remote-controlled unmanned aircraft are UAVs.


An Unmanned Aerial System (UAS) refers to the whole system (everything) that makes a UAV work including the aircraft itself, all of its ground control systems (including any laptop/tablet/smartphone, and handled flight controller), GPS module, transmission systems, camera, all its software, and also including the pilot on the ground controlling the drone.


Drone Services

Aerial Photography

Photography from a camera mounted in a manned fixed wing aircraft or helicopter, a UAV or an elevated mast.

Aerial Video/Film

Video or film shot from a camera mounted in a manned fixed wing aircraft or helicopter, a UAV or an elevated mast.

Drone Inspection

An inspection of any structure or object by a drone, typically achieved by capturing high resolution still photography images, and/or video, but may also use other sensors such as an infrared camera, or even a contact ultrasonic sensor used for measuring widths or condition of metal panels/structures.

Drone Chimney Inspection


Drone Internal Confined Space Inspection

The inspection of any internal confined space using a drone (can be aerial or terrestrial rover).
UAVs used for internal confined space inspections are typically fitted with a protective cage and more complex internal navigation systems.

Drone Roof Inspection


Drone Survey

The terms inspection and survey are often used interchangeably in the drone industry potentially causing some confusion.
At DTA we reserve the term survey for those services where measurements of height, widths and depth are taken, and/or GPS X/Y/Z location measurement for example in topographical surveying and 3D mapping.

Drone Fugitive Methane Gas Survey

A survey of a land area, building(s), or industrial site which accurately measures the level of fugitive methane gas at set points on a grid across the site.
Our clients can select their desired separation of the grid measurement points as well as specific areas of interest or concern within the survey area.
DTA is the first to offer this service in the UK using our own proprietary technology developed by our R&D team here in the UK.

Drone Measured Building Survey

A Measured Building Survey conducted using a UAV.
Typically this produces a point cloud from which an accurate, measurable 3D model of the building is generated.
See Measured Building Survey in the surveying terms section below.

NDVI - Normalized Difference Vegetation Index

NDVI is a service for agriculture.

NDVI quantifies vegetation by measuring the difference between near-infrared (which vegetation strongly reflects) and red light (which vegetation absorbs).
NDVI always lies in the range -1 to +1.
Negative values are highly likely to be water, while an NDVI close to +1 is highly likely to be dense green leaves.
NDVI is used in precision agriculture to measure biomass.
Whereas, in forestry, NDVI is used to quantify leaf area index and forestry supply (quantities).

Telecommunication Line-of-Sight Survey

Installation of directional telecommunications and microwave communications dishes typically require a line-of-sight survey to confirm that there is a direct unobstructed path between the two proposed locations of the communication dishes or masts.
This can be achieved using either drones or elevated masts.

3D Mapping & Modelling

A service to survey a land area or structure and create an accurate 3D map or 3D structural model of the subject.
There are many software tools on the market used to capture and process 3D data.
DTA has been monitoring and testing the best of these for 6 years now and we believe that our chosen systems offer our clients the best quality and features in 3D mapping and modelling.



Other Services and Equipment Used Alongside Drones

Elevated MAST

A large (typically >15 metre) metal mast raised and lowered pneumatically and with a remote-controlled pan-tilt-and-zoom gimbal mounted on top carrying a camera for aerial photography and video services.

Elevated MAST Photography

Aerial photography using an elevated mast.

Elevated MAST Video/Film

Aerial video/film using an elevated mast.



Surveying Equipment and Terminology


Global Navigation Satellite System.
The generic term for a satellite system used to accurately measure the geographic location of a user's receiver anywhere in the world.
Two GNSS systems are currently in operation: the United States' Global Positioning System (GPS) and the Russian Federation's Global Orbiting Navigation Satellite System ( GLONASS ).

GEO positioning is measured by using time-of-flight information for a signal to be transmitted from a given satellite and then received by the target GPS receiver system to then determine an accurate distance between the two.
By performing these measurement between the target GPS receiver and multiple satellites in various locations in the sky, trilateration is then used to determine a precise location of the target.


GNSS Receiver

Global Navigation Satellite System receiver.
An electronic and software device that receives and digitally processes signals from a navigation satellite constellation and measures the accurate geo-location of points on the earths’ surface in surveying.


The Global Positioning System (GPS) is the GNSS system of the United States, but used worldwide.
The term GPS is also used generically and interchangeably with GNSS (see above) which can be confusing, hence GNSS has become the generic term.

Point Cloud

A set of data points in space.
Point clouds are generally produced by 3D laser scanners or by photogrammetry software, which measure many points on the external surfaces of land or objects around them.
As the output of 3D scanning processes, point clouds are used for many purposes.
In the drone industry point clouds are captured either with a high resolution professional camera and photogrammetry software, or with a LiDAR laser scanner.
These point clouds are then used to create accurate, measurable 3D CAD models for land surveys, volume surveys, measured building surveys and 3D mapping and modelling.


Points Per Square Metre.
A measure of the density of data points in a point cloud.


Real Time Kinematics.
RTK as satellite navigation technique used to increase the precision of position data derived from a GNSS such as GPS.
Anyone that has conducted any GNSS based surveying will have experienced the difficulty in some locations in obtaining enough satellites in view to enable precision in reading taken.
RTK positioning is based on at least two GPS receivers—a base receiver and one or more rover receivers.
The base receiver takes measurements from its satellites in view and then broadcasts them, together with its own location, to the rover receiver(s).
The rover receiver(s) also collect(s) measurements from its satellites in view (likely to be a different subset of satellites) and processes them with the base station data.
The rover then estimates its location relative to the base. The combination of these multiple additional readings achieves higher precision.
In RTK mode, the GNSS on the drone itself will also be in RTK mode.


Drone Components/Parts


Measures the acceleration of the drone in a specific direction.

Allows the drone to maintain orientation. Used to stabilize drones and in navigation systems.


Digital Single-Lens Reflex Camera
A digital single-lens reflex camera (also called digital SLR or DSLR) is a digital camera that combines the optics and the mechanisms of a single-lens reflex camera with a digital imaging sensor, as opposed to photographic film.


A mounting for a drone that attaches a sensor to a drone, such as a camera, LiDAR, light. Typically, this will be motorised enabling the sensor to be moved or held in a specific configuration relative to the drone flight path.


An Inertial Measurement Unit.
An IMU is an electronic module that measures angular velocity and linear acceleration (typically using a combination of accelerometers, gyroscopes, and sometimes magnetometers).
IMUs are typically used to manoeuvre drones (an attitude and heading reference system), especially for navigation in internal spaces (where GPS does not work), and also for measuring the attitude of cameras and sensors.

Inertial Navigation System (INS)

A system calculating the position of the drone that is based on initial GPS position data, and then using accelerometers/motion and speed sensors when the GPS data is unreliable or unavailable.

Particularly useful when flying a drone in areas with no GPS signal, for example internally within buildings and structures.


A method for measuring distances (ranging) by illuminating the target with laser light and measuring the reflection with a sensor.
Differences in laser return times and wavelengths are then used to create digital 3D representations of the target.

Originally derived from the words “light” and “radar”, it is now also used as an acronym of "light detection and ranging" and "laser imaging, detection, and ranging".
LiDAR is sometimes called 3D laser scanning.
LiDAR is often used to make high-resolution maps, with applications in surveying, geodesy, geomatics, archaeology, geography, geology, geomorphology, seismology, forestry, and also for altitude control of drones (terrain following).

LiPo Battery

Almost all quadcopter batteries are LiPo batteries. This term refers to lithium polymer batteries. They are preferable for drone flying because they weigh less than regular batteries.


This term stands for milliampere-hour. It refers to how much electrical charge a battery can produce. The larger the mAH, the stronger the battery is, the more features it can power, and the longer it can run. Typically, drone batteries are 50-6000 mAH, with the strength of the battery increasing according to the size and cost of the quadcopter.

Radio Controller

The controller, as its name suggests, is responsible for controlling the flight of the quadcopter. Typically, this is a small device that fits in your hands. It usually contains two joysticks. One joystick on the right controls where the drone tilts (forward, backward, side to side). The one on the left controls the direction the drone turns and controls the take off and the landing of the drone. On more expensive drones, the controller often comes with a screen that allows you to view FPV, or even control the drone by tapping the screen.


An electronic component either transmitting from a drone to the ground, or from a ground component to the drone.
Transmitter-receiver systems are used to implement communications systems between the drone and ground components for control, and telemetry (data).

Ultrasonic Sensor

Two types of Ultrasonic sensors exist for use with drones.
i) An ultrasonic sensor that projects sound waves to the ground and then detects any reflected sound waves reflected back. Used to measure height above ground or distance from obstacles around the drone. More complex drones use these for terrain following or obstacle detection when flying indoors or close to objects under drone inspection.
ii) An ultrasonic sensor that can be pressed into contact with a metal structure to measure thickness or detect cracks due to metal fatigue or damage. Often termed a UT sensor.


Aviation/Flying Terminology


An "acrobatic" flight control mode for experienced drone pilots who want full control over the drone, also known as manual mode. Acro-mode disables auto self-levelling controls, allowing for advanced aerial manoeuvres such as flips and rolls. Not recommended for beginners.


Variants in measurements of altitude.
Above Ground Level.

Above Initiation Point (i.e. above launch/take-off of altitude).
Above Sea Level.


Atti-mode (attitude-mode) flight control mode allows the drone pilot to manually control the drone's pitch and roll while the drone flight controller maintains its altitude and heading.

This mode is often used for aerial photography and cinematography.

Autonomous Flight

Some UAVs are self-controlled by internal navigation systems using the built-in GPS system, radar or machine-vision for obstacle avoidance and situational awareness, and inertial navigation.


A flight control software feature enabling a drone to fly along an automated flight path or even hold a hovering position at a selected height.

Used in many surveying and inspection services operations.

See also Way-point Control.

AW - Aerial Work

Aerial work operations are separated from general aviation by the ICAO in its definition.

Aerial work activities include agriculture, construction, photography, surveying, observation and patrol, search and rescue, and aerial advertisement.


A plane of flight.
Most drones have at least 4-axis controls, with 6+ axes preferred.


Beyond the Visual Line of Sight.
Refers to flights conducted beyond the visual line of sight of the pilot with the unaided human eye.
Current UK regulations state that drone operations must be conducted within unaided Visual Line of Sight (VLoS), set at a maximum of 500m from the pilot.
BVLoS drone operations require special permission in the UK from the CAA, such permissions only very recently having started to be granted to PfCO operators.

CAT - Commercial Air Transport

Commercial Air Transport (CAT) operation is defined as “an aircraft operation to transport passengers, cargo or mail for remuneration or other valuable consideration”.


FPV refers to first person view. This refers to a quadcopter feature that streams the video from the camera directly to your controller or to your smart phone. When it streams to your smart phone, it is usually sent through the use of a drone-specific app that may also allow you to do things such as edit the video or share the video with friends and family. FPV is desirable because it improves the flight experience and because it can make it easier to fly the drone if the drone is out of sight.

GA - General Aviation

General aviation represents the 'private transport' and recreational components of aviation.
It also includes activities surrounding home/self-built aircraft, flight training, flying clubs, and aerial applications, as well as forms of charitable and humanitarian transportation.
Private flights are made in a wide variety of aircraft: light and ultra-light aircraft, sport aircraft, business aircraft (e.g. private jets), gliders and helicopters.

General aviation refers to the private transport and recreational flying component of aviation, as well as the manufacturing or building process of those aircraft.

General aviation is the name or term given to all civil aviation "aircraft operation other than a commercial air transport or an aerial work operations.

Headless Mode

Headless mode refers to flying the drone without regard for where its front and back are. In regular mode, the drone moves forward where its head is pointing and backward where its tail is pointing. In headless mode, it moves forward toward the controller and backward away from the controller, no matter where its head and tail are.


International Civil Aviation Organization.
The ICAO defines civil aviation aircraft operations in three categories: General Aviation (GA), Aerial Work (AW) and Commercial Air Transport (CAT).
Please refer to definition of these categories elsewhere in this section.


Instrument Flight Rules.
Where a manned aircraft pilot is flying the aircraft under instrument readouts only.
When BVLoS for UAS comes in, it is an interesting question as to whether this will generally be classed as IFR for UAS.


Maximum take-off mass/weight.


The amount of additional weight a drone can carry. If you attach a camera and gimbal to your drone, the combined weight is the payload.


Pilot In Command.
Often referred to as Pilot-In-Control, but command is correct as it is the pilot who is responsible and in overall command of the whole operation.


A UAV system supplied with all of the basic equipment necessary to fly it in one package.
e.g. requiring minimal assembly and including a battery, battery charger, a controller, and possibly more.

TOAL zone

Take-Off And Landing zone.


Visual Flight Rules.
In terms of manned aircraft a pilot flying under VFR must be able to see the ground, other aircraft and obstacles; but there is more detail to it than just that.
UAS must currently always be flown under VFR until BVLoS comes in.


Visual Line of Sight (see BVLoS above).
UK regulations require the pilot to maintain VLoS (500m) with the drone at all times during flight, unless flying under a BVLoS exemption/OSC.


Vertical Take-off and Landing.
VTOL drones are fixed wing drones that take-off and land vertically…think of the popular Harrier jump jet.
Confusingly, all copter drones also take-off and land vertically.  😊

Waypoint Control

Pre-programmed locations in a programmed flight path, typically GPS locations.


Topographical Building & Land Surveying Terminology

Topographical Land Survey

A topographical survey, also known as a land survey or topographical land survey, measures and identifies the exact location and details of natural and manmade features within an area of land.
A topographical survey picks up several different elements depending on the specification from the client.

Typical features surveyed include:

  • Ground heights/contours

  • Boundaries and fence lines

  • Buildings & structures

  • Drainage features such as inspection chambers

  • Services such as power lines

  • Street furniture such as benches, lamp posts, bins etc

  • Surfaces such as paving, tarmac, concrete etc

  • Trees, bushes and vegetation

  • Ponds, lakes, watercourses

  • Water levels

A terrestrial (surveyed while on the ground) topographical land survey is typically achieved using a laser scanner, or by taking point readings using a GNSS receiver.

Following the survey, the information is then converted into an electronic CAD (Computer-Aided Design) file. This is then presented as plan drawing which can be sent electronically and physically printed. is then drawn up into a precise and detailed plan.


Building Information Model.
A digital model of the physical and functional characteristics of a building or facility.
A BIM is a shared knowledge resource for information about a facility forming a reliable basis for decisions during its life-cycle; defined as existing from earliest conception to demolition.


Ground sample distance.
Taking two consecutive pixel centres within a photogrammetry image, GSD is the distance measured on the ground between the points on the land surface that these pixels represent/record.
The bigger the value of the image GSD, the lower the spatial resolution of the image and the less visible details. GSD is related to the flight height: the higher the altitude of the flight, the bigger the GSD value for a given camera.


Ground Control Point.
Ground Control Points, or GCPs, are marked points on the ground that have a known geographic location.
In aerial surveying, GCPs must be visible in the aerial photos taken in order to provide an accurate lock between the points measured within the survey and the real-world location of those points on the earth’s surface.

GCPs, thus enhance the positioning and accuracy of the mapping outputs.

Many drone services will claim that GCP’s are not needed. This is NOT TRUE.

The number of GCP’s needed for accurate surveying can be reduced by using a technology called RTK in the drone, but even then this only reduces the number needed and does not eliminate them. A Chartered Surveyor will confirm this.

Measured Building Survey (MBS)

A Measured Building Survey is one where either a terrestrial laser scanner or UAV, or both combined, is used to measure the locations of a large number of points on the walls, roof, and by definition all visible structural elements of a building, creating a point cloud containing these points, and then generating an accurate, measurable 3D model of the complete building (or part of).
Measured Building Survey are rapidly becoming very popular as companies and organisations being to seek compliance with BIM processes and standards.


Photogrammetry is process of calculating measurements from photographs, especially for calculating the exact positions of land surface points in aerial land surveying (including precise position and elevation on the earth’s surface).

Digital Camera Sensor Formats

Illustration of relative sizes of digita

Image courtesy of Wikipedia


The image above illustrated the differing size of the CMOS sensor inside the digital camera.

The senor is the central component of the camera that receives and senses the incoming light and records the image (the camera retina essentially).

The larger the sensor area, then the larger is the area of sensor for recording each pixel of the digital image. Increasing the sensor area per pixel results in more light being used to record each pixel, i.e. more data resulting in a higher quality image at a pixel level.


Please note: the (Sony, Nikon) 1” sensor was used in the DJI X4S (DJI’s only leaf shutter camera). The X4S is now discontinued and DJI’s alternatives have both smaller sensors and digital rolling shutter. Note the big difference in sensor area between it and the 35mm full frame that we recommend as a minimum requirement.



Leading Commercial Drone Companies & Systems

Autel Robotics

Not to be confused with, a manufacturer and supplier of professional diagnostic tools.

Autel Robotics is not such a well known UAV technology company, but rapidly becoming more so, oddly riding particularly on the bandwagon of bans/restrictions on the use of DJI drones in the USA.

Founded in 2014, although headquartered in Seattle, Autel Robotics is Chinese owned, its parent company being Autel Intelligent Technology.

All of manufacturing is based in China.

AR can be argued to be the only true DJI competitor currently with a like-for-like product line-up almost across the board which in DTA's experience closely challenge the quality, feature set and pricing of DJI.


The world's leading UAV technology company widely respected in the drone industry and community for making technology leading quality drones, gimbals, and other components.
DJI is a Chinese company and is regularly the subject of speculation and legislative technology controls, particularly in the USA, regarding its potential links to the Chinese State and Military, also being suspected/accused of data monitoring and mining.

Please note that due to national security concerns, DJI drones are no longer permitted to fly over USA DoD, UK MoD and other government sites in the USA, UK and some other countries.

Should this cause you problems in procuring drone services for these sites do call us immediately.
We can still fly our own proprietary drones on these sites for inspections, topographical surveys, measure building surveys, photography and video.


A leading Swiss UAV technology company specialised in the supply of drone for internal confined space inspections.

Aviation Regulations (especially those relating to Drones)


United Kingdom Civil Aviation Authority.
The government body responsible for regulating the use of drones and all flying systems in UK airspace.

Commercial Flight

The flying of drones for business/commercial purposes.
Currently regulated in the UK by UK CAA requiring all organisations operating commercially to hold a Permit For Commercial Operation of drones (PfCO).


European Union Aviation Safety Agency.


United States Federal Aviation Authority.


National Airspace System.
Mostly a United States term denoting the common network of airspace, air navigation facilities, equipment and services, airports or landing areas; aeronautical charts, information and services; rules, regulations and procedures, technical information; and manpower and material.


Operational Safety Case.
A carefully designed set of safe-operating procedures, defined by a drone operator and then submitted to, audited and approved by the UK CAA, which then permits that drone operator to operate drones outside of the limits of the standard permissions. This most often pertains to permission to operate at reduced distances from buildings, people, roads etc., and BVLOS.

No Fly Zone

Areas where flying a drone is restricted by government regulations. Areas where a drone could interfere with an airplane or record sensitive information make up most of these areas.


A Permit for Commercial Operation of drones issued by the CAA in the UK.
This is currently a legal requirement for conducting commercial operation using UAV drones in the UK.

Health, Safety and Environmental


ATEX is the name commonly given to the two European Directives for controlling explosive atmospheres.

ATEX equipment ratings are required for all equipment that can safely operate within explosive atmospheres.


Two European directives define ATEX:

1) Directive 99/92/EC (also known as 'ATEX 137' or the 'ATEX Workplace Directive') on minimum requirements for improving the health and safety protection of workers potentially at risk from explosive atmospheres.


2) Directive 2014/34/EU (also known as 'ATEX 114' or 'the ATEX Equipment Directive') on the approximation of the laws of Members States concerning equipment and protective systems intended for use in potentially explosive atmospheres.


We currently only know of one drone technology company that has manufactured and supplied ATEX rated drones, the French company Xamen.

Xamen has now ceased trading.


Two abbreviations:

Health and Safety Executive - a UK government authority,

Health,  Safety & Environmental - as used in company documentation, department naming, and management titles.


Health,  Safety & Environmental - Management System.


National Examination Board in Occupational Safety and Health.
UK Government board setting qualifications and examinations for HSE management.

DTA has a NEBOSH qualified HSE Manager.


Risk Assessment and Method Statement (in reality two documents delivered as one package).

Essentially these ensure that all possible risks related to an operation on a specific site have been identified, documented, and methods of mitigating and managing those risks have been planned, with all necessary and associated personnel have been clearly informed and instructed.
Risk assessments are a legal requirement and as such, every project conducted by DTA will have a RAMS document supplied to the clients and all personnel on-site likely to be involved with the operations.

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