ISO/FDIS 9849

ISO/TC 172/SC 6
Secretariat: SNV
Date: 2025-12-312026-xx
Optics and optical instruments — Geodetic and surveying
instruments — Vocabulary
Optique et instruments d’optique intruments d'optique — Instruments géodésiques et
d’observationd'observation — Vocabulaire
FDIS stage
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Types of geodetic instruments and related terms . 1
3.2 Parts of geodetic instruments . 11
Bibliography . 23
Index 24
Foreword . iii
Introduction . iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Types of geodetic instruments and related terms . 1
3.2 Parts of geodetic instruments . 11
Bibliography . 24
Index . 25

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO [had/had not] received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that this
may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 6,
Geodetic and surveying instruments.
This fourth edition cancels and replaces the third edition (ISO 9849:2017), which has been technically revised.
The main changes are as follows:
— — definitions added for GPR, UAV, range camera, pole and marker;
— — sub-categories added for GNSS, 3D laser scanner and graduated circle;
— — editorial corrections.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
This document forms one of a series concerning geodetic and surveying instruments. It gives terms and
definitions of terms which may be used in the drafting of other International Standards and national standards
in this field.
This document defines terms as they are used to describe geodetic and surveying instruments for geodetic
work and their essential parts. It is intended for both the surveyor and the non-surveyor. The use of these
definitions related to other fields may not be appropriate. Every reader is requested to use only these terms
in the future so that, with time, a standard and acceptable terminology will come into common usage.
v
Optics and optical instruments — Geodetic and surveying
instruments — Vocabulary
1 Scope
This document defines terms relating to geodetic and surveying instruments, such as distance meters, levels,
theodolites, GNSS, total stations, laser scanners, airborne sensors and others, and their essential components
and accessories which are used in measuring operations, such as land surveying, topographic surveying,
construction surveying and engineering geodesy.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminologicalterminology databases for use in standardization at the following
addresses:
— — IEC Electropedia: available at https://www.electropedia.org/
— — ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Types of geodetic instruments and related terms
3.1.1 3.1.1
alignment instrument
device used to aim at intermediate points and to a reference target at the end of an alignment
Note 1 to entry: The device is usually equipped with a powerful magnifying telescope (3.2.38(3.2.38).).
3.1.1.1 3.1.1.1
alignment laser
alignment instrument (3.1.1(3.1.1)) using a laser beam as reference line or reference plane instead of an optical
line of sight
3.1.1.1.1 3.1.1.1.1
point laser
plumb laser
pipe laser
alignment laser (3.1.1.1(3.1.1.1)) which projects a single point on a surface using a reference line of a laser
beam
3.1.1.1.2 3.1.1.1.2
line laser
laser marker
cone laser
cross-line laser
alignment laser (3.1.1.1(3.1.1.1)) which projects one or more lines or planes on a surface using a reference
plane of a laser beam with a certain opening angle
Note 1 to entry: Instrument can be used for marking horizontal or vertical surfaces by a visible laser.
Note 2 to entry: A specific type of line laser for planar coverage is for example a rotating laser (3.1.16(3.1.16).).
3.1.2 3.1.2
barometer
instrument for measuring atmospheric pressure
Note 1 to entry: Barometers can be used for the atmospheric reduction of electronically measured distances or as
barometric altimeters (3.1.2.2(3.1.2.2).).
3.1.2.1 3.1.2.1
aneroid barometer
barometer (3.1.2(3.1.2)) in which atmospheric pressure is balanced by some elastic elements as a method that
does not involve liquid
3.1.2.2 3.1.2.2
barometric altimeter
barometer (3.1.2(3.1.2)) used for elevation measurement, in which case a read out is provided in
metersmetres
3.1.2.3 3.1.2.3
mercury barometer
barometer (3.1.2(3.1.2)) in which atmospheric pressure is balanced by the mass of a column of mercury
3.1.2.4 3.1.2.4
electronic barometer
instrument for measuring atmospheric pressure by conversion of physical observation to electrical signals
3.1.3 3.1.3
electro-optical distance meter
electronic distance meter
EDM
instrument for measuring distances between the instrument and a reflective target, using various electro-
optical techniques, visible light or infrared radiation as carrier waves
Note 1 to entry: The target can be a reflector (3.1.15(3.1.15)) or any other surface.
Note 2 to entry: See also total station (3.1.20(3.1.20),), hand-held laser distance meter (3.1.7(3.1.7),), terrestrial laser
scanner (3.1.8.1(3.1.8.1)) and laser tracker (3.1.9(3.1.9).).
3.1.3.1 3.1.3.1
phase shift distance meter
electro-optical distance meter (3.1.3(3.1.3)) which is based on the phase comparison of two modulation
signals, one is the reference signal, the other the return signal from the reflective target
Note 1 to entry: The phase difference can be detected by various methods and is used to calculate the distance.
3.1.3.2 3.1.3.2
pulsed distance meter
time of flight distance meter
electro-optical distance meter (3.1.3(3.1.3)) which is based on measuring the time of flight between
transmission and reception of the same pulse
3.1.4 3.1.4
field controller
tablet
data collector
device that controls a surveying instrument -, such as total station (3.1.20(3.1.20),), GNSS receiver
(3.1.5.1(3.1.5.1),), 3D laser scanner (3.1.8(3.1.8)) or digital level (3.1.10.2(3.1.10.2) -), by using on-board
applications, recalls surveying data or other information and records and analyses measurement data of the
instruments
3.1.5 3.1.5
global navigation satellite system
GNSS
system consisting of several satellites in different orbital planes, which allow absolute navigation solutions as
well as high precise (e.g. differential) positioning and broadcasting of time due to the global coverage
Note 1 to entry: GNSS includes all operating global navigation systems by satellite.
EXAMPLE 1 Global positioning system (GPS) or navigational satellite timing and ranging – Global positioning system
(NAVSTAR-GPS) – US Department of Defence navigation system based on the constellation of usually more than
24 satellites at an altitude of 20 200 km above earth’s surface.
EXAMPLE 2 GLObal’naya NAvigationnaya Sputnikovaya Sistema (GLONASS) – Russia's global navigation satellite
system based on the constellation of approximately 24 satellites at an altitude of 19 100 km above earth’s surface.
EXAMPLE 3 Galileo – Global navigation satellite system organized by EU and European Space Agency. The system is
planned to consist of 30 satellites at an altitude of 23 200 km above earth’s surface.
EXAMPLE 4 BeiDou – Navigation satellite system (BDS) organized by China. More than 54 satellites in medium earth
orbit (22 000 km above earth’s surface) as well as in geosynchronous orbit (35 790 km above earth’s surface) are used,
where the latter include satellites in both geostationary orbit and in inclined geosynchronous orbit.
EXAMPLE 5 Quasi-Zenith Satellite System (QZSS) – Satellite navigation system operated by Japan. The system
complements GPS, especially in the Asia-Pacific region, and consists of a constellation of typically 4 satellites in
geostationary orbit as well as highly elliptical, quasi-zenith orbit (32 600 km to 38 950 km above earth’s surface).
3.1.5.1 3.1.5.1
GNSS receiver
electronic device that receives and digitally processes the signals from GNSS satellites in order to provide
position, velocity and time (of the receiver)
3.1.5.2 3.1.5.2
differential GNSS
DGNSS
processing application within mobile GNSS receivers, using difference techniques of GNSS observations and
additional reference point or reference network GNSS observations
Note 1 to entry: In differential GNSS (DGNSS) applications, correction data and additional information from a known
reference station are used by mobile rovers, enabling them to improve position accuracy.
3.1.5.2.1 3.1.5.2.1
differential GPS
DGPS
DGNSS (3.1.5.2(3.1.5.2)) application using only observations from the GPS (Navstar satellite system) and
additional reference point or reference network GPS observations
3.1.5.2.2 3.1.5.2.2
differential BDS
DBDS
DGNSS (3.1.5.2(3.1.5.2)) application using only observations from the BDS (BeiDou navigation satellite
system) and additional reference point or reference network BDS observations
3.1.5.3 3.1.5.3
real-time kinematic
RTK
real-time processing algorithm technique of mobile GNSS receivers using the carrier phase of GNSS
observations for a positioning of the mobile GNSS receiver within a reference network in a low cm-level
Note 1 to entry: In real-time kinematic (RTK) application, measurements of the phase of the signal’s carrier wave are
used to provide real-time corrections. By a data link from the reference station to the rover station, the corrections are
transmitted to enhance the precision of the position up to cm-level.
3.1.5.4 3.1.5.4
GNSS measuring instrument
measuring equipment for the determination of coordinates on the basis of satellite-supported positioning
Note 1 to entry: A GNSS measuring instrument consists, e.g., of GNSS antenna, GNSS receiver (3.1.5.1(3.1.5.1),), and field
controller (3.1.4(3.1.4).).
3.1.5.5 3.1.5.5
choke ring antenna
type of omnidirectional antenna, consisting of a central antenna element surrounded by several concentric
conductive rings, which eliminate multipath signals
Note 1 to entry: Typically used for GNSS applications which require highest accuracy such as reference stations.
3.1.5.6 3.1.5.6
continuously operating reference station
CORS
GNSS reference station or its network system which continuously provides raw satellite observations and
positioning information in real-time
3.1.5.7 3.1.5.7
virtual reference station
VRS
method of using a network of physical reference stations to interpolate and transmit correction data of a
virtually established reference station in the vicinity of the mobile GNSS receiver (3.1.5.1(3.1.5.1))
Note 1 to entry: VRS can be used e.g. for both RTK (3.1.5.3(3.1.5.3)) and post-processing applications.
3.1.6 3.1.6
gravimeter
gravity meter
gravity instrument
instrument for measuring the absolute gravity or the differences in the value of gravity
3.1.7 3.1.7
hand-held laser distance meter
electro-optical distance meter (3.1.3(3.1.3)) which is used and held usually with the hands
Note 1 to entry: Usually, reflectorless EDM techniques are used.
3.1.8 3.1.8
3D laser scanner
measuring equipment using a scanning technology by a laser beam to produce detailed 3D point cloud data
including intensity of complex structures and objects and geometries
3.1.8.1 3.1.8.1
terrestrial laser scanner
TLS
3D laser scanner (3.1.8(3.1.8)) which is set up as a ground-based instrument
3.1.8.2 3.1.8.2
airborne laser scanner
airborne topographic scanner
3D laser scanner (3.1.8(3.1.8)) which is set up on an aircraft to scan the earth’s surface while flying
3.1.8.3 3.1.8.3
hand-held laser scanner
3D laser scanner (3.1.8(3.1.8)) which is set up as mobile instrument to scan the surrounding while carried by
operator
3.1.9 3.1.9
laser tracker
coordinate measuring system in which a cooperative target is followed with a laser beam and its location
determined in terms of a distance (range) based on laser interferometry techniques and two angles
Note 1 to entry: Cooperative target can be a retroreflector (3.1.15.1(3.1.15.1).).
3.1.10 3.1.10
level
instrument for measuring differences in height by establishing horizontal lines of sight, comprising as main
components a telescope (3.2.38(3.2.38)) which can be rotated on a vertical axis (3.2.44(3.2.44)) and a facility
for levelling the line of sight
Note 1 to entry: It can be additionally fitted with a horizontal circle (3.2.7(3.2.7)) and/or a parallel plate micrometer
(3.2.23(3.2.23).). The reticule has sometimes stadia hairs for optical distance measurement.
Note 2 to entry: See also spirit level (3.2.16(3.2.16)) and tachymeter (3.1.17(3.1.17).).
3.1.10.1 3.1.10.1
automatic level
compensator level
self-levelling level
pendulum level
level which makes use of a tilt compensator (3.2.39(3.2.39)) that ensures that the line of sight is horizontal
once the operator has roughly levelled the instrument
3.1.10.2 3.1.10.2
digital level
level which electronically reads a sequence of code patterns on the levelling staff (3.1.11(3.1.11)) by an image
sensor
Note 1 to entry: These instruments usually include data recording capability. The automation removes the requirement
for the operator to read a scale.
Note 2 to entry: The processing and the display of the results are taken by an integrated computer.
3.1.10.3 3.1.10.3
electronic level
inclinometer
tiltmeter
instrument which detects inclination or changes of inclination under the influence of gravity by the use of
electronic sensors
Note 1 to entry: For the realization as sub-component of an instrument, see electronic level (3.2.16.3(3.2.16.3).).
3.1.10.4 3.1.10.4
tilting level
manual level
level which provides a tilting screw to establish a levelled line of sight
3.1.11 3.1.11
levelling staff
levelling rod
level rod
straight bar with a scale on a flat face
Note 1 to entry: The levelling staff can be made of, for example, metal, glass fibre or wood.
Note 2 to entry: The levelling staff is used to measure the vertical distance between a base point and the horizontal line
of sight of a level (3.1.10(3.1.10).).
3.1.11.1 3.1.11.1
digital levelling staff
bar code staff
levelling staff (3.1.11(3.1.11)) for levelling with a digital level (3.1.10.2(3.1.10.2)) having a specified code
patterns on the flat face
3.1.11.2 3.1.11.2
invar levelling staff
precise levelling rod
invar rod
levelling staff (3.1.11(3.1.11)) for precise levelling, having an invar strip with graduation lines or code patterns
(bar code)
−6
Note 1 to entry: Invar is a Fe-Ni alloy to ensure a low coefficient thermal expansion (<10 /K).
3.1.12 3.1.12
optical plummet
instrument or device that realizes a visible line of sight in a vertical zenith or nadir direction
Note 1 to entry: The optical plummet can be levelled by liquid horizon, tubular levels or compensators.
Note 2 to entry: An optical plummet can also be a part of a geodetic instrument.
Note 3 to entry: It can be used for placing a marker (3.1.23(3.1.23)) on the ground or centring an instrument over a
marker (3.1.23(3.1.23)) on the ground (nadir plummet) as well as for centring an instrument under a point (zenith
plummet).
3.1.12.1 3.1.12.1
laser plummet
optical plummet (3.1.12(3.1.12)) which uses a laser beam as a visual plumb line
Note 1 to entry: A laser plummet can also be combined with an electro-optical distance meter (3.1.3(3.1.3)) for
measuring the instrument height above ground.
3.1.12.2 3.1.12.2
optical precise plummet
optical plummet (3.1.12(3.1.12)) comprising a telescope with high magnification and precise devices (e.g.
bubbles, compensator) to precisely realize the vertical line of sight
3.1.13 3.1.13
optical square
pentaprism
device equipped with pentagonal prism for determination of orthogonal lines of sight
3.1.14 3.1.14
plane table
device used in surveying and related disciplines to provide a solid and level surface on which to make field
drawings, charts and maps
Note 1 to entry: As a sighting instrument, usually, an alidade is used on the plane table.
Note 2 to entry: See also 3.2.273.2.27 for a description for a plane table as a part.
3.1.15 3.1.15
reflector
device at the target which reflects the light beam to an electro-optical distance meter (3.1.3(3.1.3)) or to a
tracker system
Note 1 to entry: These devices are, for example, glass prism reflectors, corner cube reflectors, acrylic reflectors,
reflecting sheets.
Note 2 to entry: Reflectors are usually provided on a pole (3.1.22(3.1.22)) having a centring device. A 360° reflector
device has multiple glass prisms which are measurable from any horizontal direction.
3.1.15.1 3.1.15.1
retroreflector
passive device designed to reflect light back parallel to the incident direction over a range of incident angles
Note 1 to entry: These devices are, for example, glass prism reflectors, corner cube reflectors.
3.1.15.2 3.1.15.2
reflective tape
reflecting tape
reflecting sheet
reflector (3.1.15(3.1.15)) of plane sheet or tape comprised of tiny prisms made of a flexible material
3.1.16 3.1.16
rotating laser
laser level
rotary laser
instrument generating a plane by means of a rotating laser beam
3.1.17 3.1.17
tachymeter
tacheometer
instrument for measuring horizontal directions, vertical angles and distances
Note 1 to entry: A tachymeter is basically a theodolite (3.1.19(3.1.19)) enhanced with the capability to measure
distances.
3.1.18 3.1.18
target
target plate
symmetrical figure, structure or reflector defining a point on the target to which observations are taken
Note 1 to entry: It is usually provided with some form of a forced-centring device (3.2.13(3.2.13).).
3.1.19 3.1.19
theodolite
transit
optical instrument for measuring horizontal directions and vertical angles, whose main components are the
horizontal circle and the vertical circle inclusive reading systems, the telescope (3.2.38(3.2.38)) and the
alidade (3.2.1(3.2.1)) inclusive the horizontal and vertical rotation axes
Note 1 to entry: The telescope can be rotated around the horizontal axis (3.2.15(3.2.15)) and vertical axis
(3.2.44(3.2.44).).
Note 2 to entry: A theodolite can also be used for optical distance measurement.
Note 3 to entry: A theodolite used in astronomical work is usually termed an astronomical theodolite or a transit
instrument.
3.1.19.1 3.1.19.1
compass theodolite
compass transit
theodolite (3.1.19(3.1.19)) attached with a centrally mounted compass (3.2.6(3.2.6)) for determining the
magnetic azimuth
3.1.19.2 3.1.19.2
electronic theodolite
theodolite (3.1.19(3.1.19)) with microprocessor(s), display and memory for automatic reading, processing,
displaying and storing of measurement data
3.1.19.3 3.1.19.3
gyrotheodolite
gyro-azimuth theodolite
survey gyroscope
theodolite (3.1.19(3.1.19)) with a north-seeking gyro attached for the determination of the geographic north
direction
Note 1 to entry: In general, both theodolite and gyro form one unit. Different observation methods allow to determine
the geodetic azimuth.
3.1.19.4 3.1.19.4
suspension theodolite
theodolite (3.1.19(3.1.19)) in a hanging position to carry out measurements in the region of nadir, prior used
for mining surveys
3.1.20 3.1.20
total station
electronic tachymeter
electronic tacheometer
tachymeter (3.1.17(3.1.17)) with microprocessor(s), display and memory for opto-electronic distance
measurement, angle reading, processing, displaying and storing of measurement data
3.1.20.1 3.1.20.1
multistation
combines combination of the functionality of a total station (3.1.20(3.1.20),), terrestrial laser scanner
(3.1.8.1(3.1.8.1)) and of imaging in one instrument
Note 1 to entry: A multistation (3.1.20.1(3.1.20.1)) has often the possibility to attach or integrate a GNSS, wireless
transmission techniques and other devices used for surveying.
3.1.20.2 3.1.20.2
non-prism total station
reflectorless total station
total station with capability to measure the distance to almost any object without the need of a specific
reflector
3.1.20.3 3.1.20.3
gyro total station
total station with a north-seeking gyro attached for the determination of the geographic north direction
3.1.20.4 3.1.20.4
double-image tacheometer
tacheometer (3.1.17(3.1.17)) with the optical wedge system included in the path of the rays in the telescope
(3.2.38(3.2.38))
Note 1 to entry: It divides the image of a horizontal staff into two horizontally displaced images. The size of the
displacement is the index of the distance reduced for the difference in height.
3.1.21 3.1.21
tripod
three-legged stand to which instruments or accessories can be attached and set up in a stable manner on the
ground
Note 1 to entry: The tripod consists of a head and three legs made of wood or metal, with metal tips. The legs are either
rigid or telescopic and connected with the tripod head by joints. The tribrach (3.2.41(3.2.41)) is fixed on the head of the
tripod.
3.1.22 3.1.22
pole
range pole
reflector pole
GNSS pole
straight rod which is used to project points of interest to a different working height
Note 1 to entry: Can be used for example with reflectors (3.1.15(3.1.15)) or GNSS receivers (3.1.5.1(3.1.5.1)) which are
attached to the pole.
Note 2 to entry: Often a pole is extendable, includes a printed height scale and an analogue bubble for levelling.
Note 3 to entry: A pole can also include sensors to measure the height extend and/or the amount of tilt, for example.
3.1.23 3.1.23
marker
marking
indication of a measured or staked out point in the region of interest
Note 1 to entry: Short-term markers with a foreseeable limited usage period are used, for example, to lay out design
data in the process of building construction or to set temporary ground control points (GCPs) during photogrammetric
measurement sessions.
Note 2 to entry: Long-term markers with an indefinite usage period, such as a survey marker (3.1.23.1(3.1.23.1),), are
stably anchored objects which mark key survey points of known position on the Earth's surface.
Note 3 to entry: Examples of markers can be printed or engraved indicators, physical objects or projected light.
3.1.23.1 3.1.23.1
survey marker
geodetic mark
permanent and solid object indication of a key survey point of known position on the Earth's surface
Note 1 to entry: Often represented by metal disks set in concrete or border stones used e.g. as triangulation point or
benchmark in geodesy and land surveying.
3.1.23.2 3.1.23.2
reference marker
reference mark
survey marker (3.1.23.1(3.1.23.1)) of highest-grade, independently verified accuracy
3.1.24 3.1.24
hydrostatic level
level that consists of two or more glass tubes connected by flexible tubing filled with a fluid whose surfaces in
the glass tubes define a reference level
Note 1 to entry: Device typically consistsconsisting of two static heads of liquid, to measure changes in height by
hydrostatic pressure difference.
Note 2 to entry: This device can be used for deformation measurement of buildings and structures.
3.1.25 3.1.25
ground penetrating radar
GPR
device that transmits electromagnetic energy into the ground which is reflected, refracted, or scattered back
to the surface depending on the features it encounters
Note 1 to entry: can be used for measuring subsurface location and thickness of natural structures, such as rock, ice or
snow layers, or urban structures such as pipes, cables or masonry.
3.1.26 3.1.26
mobile mapping system
MMS
moveable measurement system generating geo-referenced observation data using multiple sensor systems
Note 1 to entry: MMS are frequently used to investigate and document the state of infrastructure.
Note 2 to entry: Unmanned aerial vehicles (3.1.27(3.1.27)) are often typical MMS platforms.
3.1.27 3.1.27
unmanned aerial vehicle
UAV
unmanned aircraft system
UAS
remotely or autonomously controlled flight system
Note 1 to entry: UAVs can typically carry surveying instrumentation such as a digital aerial camera (3.2.48(3.2.48),), 3D
laser scanner (3.1.8(3.1.8),), GNSS receivers (3.1.5.1(3.1.5.1)) and IMUs (3.2.49(3.2.49).).
Note 2 to entry: UAVs typically can be classified into single-rotor, multi-rotor, fixed-wing and hybrid design.
3.2 Parts of geodetic instruments
3.2.1 3.2.1
alidade
turning board
DEPRECATED: alhidade, alhidad, alidad
device that allows one to sight a distant object and uses the line of sight to perform a task, consisting of an
upper part (3.2.42(3.2.42)) or turning part of a theodolite or total station with telescope (3.2.38(3.2.38)) which
can be rotated around the standing axes (3.2.44(3.2.44)) with or without vertical circle and an opto-electronic
distance-measuring device
Note 1 to entry: This task can be, for example, to draw a line on a plane table (3.1.14(3.1.14)) in the direction of the
object or to measure the angle to the object from some reference point.
3.2.2 3.2.2
base part
lower part
bottom part
centring flange
integrated group of parts of a theodolite (3.1.19(3.1.19)) or the total station (3.1.20(3.1.20),), supporting the
limb (3.2.18(3.2.18)) and the upper part (3.2.42(3.2.42),), and are firmly attached to the tribrach
(3.2.41(3.2.41)) during the measurement
Note 1 to entry: The base part consists essentially of the bearings for the vertical axis (3.2.44(3.2.44)) and connecting
devices for the detachable tribrach.
3.2.3 3.2.3
base plate
lower part of the tribrach (3.2.41(3.2.41),), connected by screws to the spring plate (3.2.36(3.2.36)) and the
foot screws (3.2.12(3.2.12),), which rest on this metal plate
3.2.4 3.2.4
circle drive
device for turning the horizontal and vertical circle of a theodolite (3.1.19(3.1.19)) or total station
(3.1.20(3.1.20)) [usually the telescope (3.2.38(3.2.38)])] in relation of the fixed parts
3.2.5 3.2.5
clamp
device which enables rotating parts of the instrument to be clamped together when precisely sighting a target,
usually with clamps on the horizontal and vertical axis circles
Note 1 to entry: There are different types of clamps: central clamp, coaxial clamp and friction clamp (also called friction
brake).
Note 2 to entry: See also fine-motion device (3.2.10(3.2.10).).
3.2.5.1 3.2.5.1
horizontal clamp
device for clamping the upper part (3.2.42(3.2.42)) to the base part (3.2.2(3.2.2)) of a theodolite
(3.1.19(3.1.19)) or total station (3.1.20(3.1.20))
Note 1 to entry: See also horizontal fine-motion device (3.2.10.1(3.2.10.1).).
3.2.5.2 3.2.5.2
repetition clamp
device of a theodolite (3.1.19(3.1.19)) or a total station (3.1.20(3.1.20)) for clamping the horizontal circle to
the upper part (3.2.42(3.2.42)) in order to fix mechanically and temporarily a certain angle to the upper part
3.2.5.3 3.2.5.3
vertical clamp
device for clamping the horizontal axes (3.2.15(3.2.15)) in order to fix mechanically and temporarily a certain
angle to the telescope (3.2.38(3.2.38)) in respect to the vertical axis (3.2.44(3.2.44))
Note 1 to entry: See also vertical fine-motion device (3.2.10.2(3.2.10.2).).
3.2.6 3.2.6
compass
device which can be mounted on a theodolite (3.1.19(3.1.19)) or total station (3.1.20(3.1.20)) in order to orient
the horizontal circle according to the direction of magnetic north
Note 1 to entry: Various types are full circle compass, line compass or case compass and tubular compass.
3.2.7 3.2.7
circle
graduated circle
disc with a circular scale graduated in degrees or other code patterns which may be subdivided
Note 1 to entry: The disc is usually made of glass.
Note 2 to entry: The disc is sometimes graduated in gons.
Note 3 to entry: Electronic theodolites (3.1.19.2(3.1.19.2)) have coded circular scales on discs which are scanned
electronically.
Note 4 to entry: The horizontal circle for measuring horizontal directions is mounted centrally on the vertical axis
(3.2.44(3.2.44)) and securely attached to the base part (3.2.2(3.2.2)) during measurement.
Note 5 to entry: The vertical circle for measuring vertical angles is fixed at right angles to and centrally on the horizontal
axis (3.2.15(3.2.15).).
3.2.7.1 3.2.7.1
incremental circle
circle (3.2.7(3.2.7)) with evenly spaced code patterns indicating relative angle positions
3.2.7.2 3.2.7.2
absolute circle
circle (3.2.7(3.2.7)) with specific code patterns indicating absolute angle positions
3.2.8 3.2.8
display
device which indicates the measured quantity or various information which is necessary for operation
Note 1 to entry: An electronic display is usually used in electro-optical distance meters (3.1.3(3.1.3),), electronic
theodolites (3.1.19.2(3.1.19.2)) or total station (3.1.20(3.1.20),), digital level (3.1.10.2(3.1.10.2)) and others, e.g. to show
the instrument status, current operations, results of measurements or calculations.
3.2.8.1 3.2.8.1
touch screen
finger-sensitive display to operate the instrument by finger or by pen in addition to or instead of keys
3.2.9 3.2.9
eyepiece
ocular
telescope (3.2.38(3.2.38)) lens group which is nearest to the eye and with which the image formed by the
preceding elements is viewed
Note 1 to entry: It can be focused so that it produces a sharp image of the reticule (3.2.30(3.2.30)) adapted to the
individual human eye of the observer.
3.2.9.1 3.2.9.1
prismatic diagonal eyepiece
prismatic eyepiece
eyepiece prisms
eyepiece (3.2.9(3.2.9)) used in connection with a telescope (3.2.38(3.2.38)) in order to make possible or
facilitate steep sights
3.2.10 3.2.10
fine-motion device
slow-motion device
device for rotating the clamped axis by controlled small smooth movements
Note 1 to entry: There are two special (combined) types of fine-motion: rough-fine-motion and endless fine-motion.
Note 2 to entry: See also clamp (3.2.5(3.2.5).).
3.2.10.1 3.2.10.1
horizontal fine-motion device
device for fine motion of the upper part (3.2.42(3.2.42))
Note 1 to entry: See also horizontal clamp (3.2.5.1(3.2.5.1).).
3.2.10.2 3.2.10.2
vertical fine-motion device
device for the fine motion of the telescope (3.2.38(3.2.38)) on the horizontal axis (3.2.15(3.2.15))
Note 1 to entry: See also vertical clamp (3.2.5.3(3.2.5.3).).
3.2.11 3.2.11
focusing drive
focusing knob
focusing ring
device for focusing the image in the telescope (3.2.38(3.2.38),), by means of which the focusing lens can be
moved in order to shift the image generated by the objective lens into the plane of the reticule (3.2.30(3.2.30))
Note 1 to entry: At image total stations, it is also used to get a sharp live video stream from the telescope camera
(3.2.46.1(3.2.46.1).).
3.2.12 3.2.12
foot screw
component part of the tribrach (3.2.41(3.2.41))
Note 1 to entry: Usually, 3 foot screws are used for levelling the tribrach.
3.2.13 3.2.13
forced-centring device
constrained-centring device
centring
device whereby instruments and accessories are interchangeable by means of simple manual operation on
tripods (3.1.21(3.1.21),), tribrachs (3.2.41(3.2.41)) or pillars without the centring being lost at a certain
position
Note 1 to entry: Usually, the tribrach has the function of a forced centring device.
3.2.14 3.2.14
gyroscope
gyro
device for measuring and maintaining orientation in space
Note 1 to entry: Gyroscopes are based on various principles: mechanical or microelectromechanical systems (MEMS)
gyroscopes, laser or fibre optic gyroscopes or quantum gyroscopes.
Note 2 to entry: A mechanical gyroscope contains a rotating body on an axis that can turn freely in any direction, so that
the body resists the action of an applied force and maintains the same orientation in space irrespective of the movement
of the surrounding structure.
3.2.14.1 3.2.14.1
gyrocompass
device to determine astronomic north (true north) by means of gyroscope (3.2.14(3.2.14))
Note 1 to entry: See also gyrotheodolite (3.1.19.3(3.1.19.3)) and gyro total station (3.1.20.3(3.1.20.3).).
3.2.15 3.2.15
horizontal axis
tilting axis
elevation axis
axis on which the telescope (3.2.38(3.2.38)) rotates up and down when moved vertically
Note 1 to entry: The horizontal axis is arranged normal to the optical axes of the telescope.
3.2.16 3.2.16
spirit level
level
bubble level
closed hollow vial which is partially filled with liquid, the remaining space containing air which finds its way
to the highest point in the vial
Note 1 to entry: It is designed to indicate whether a surface is horizontal (levelled) or to measure the tilt of the surface
against the horizon.
Note 2 to entry: Electronic level sensors measure the tilt automatically.
Note 3 to entry: The level is used for levelling instruments, instrument parts and/or accessories. The main types are the
circular level (3.2.16.1(3.2.16.1)) and the tubular level (3.2.16.2(3.2.16.2).).
Note 4 to entry: See also level (3.1.10(3.1.10).).
3.2.16.1 3.2.16.1
circular level
bull's eye level
box bubble
circular bubble
circular, flat-bottomed device with the liquid under a slightly convex glass face with a circle mark at the centre
Note 1 to entry: It serves to level a surface in all directions across a plane.
Note 2 to entry: The graduation is normally a circle of approximately the same diameter as the bubble. In special cases,
the graduation consists of a number of concentric circles. Circular levels are normally used when a high degree of
precision is not required.
3.2.16.2 3.2.16.2
tubular level
spirit level (3.2.16(3.2.16)) with a tubular glass vial which is barrel-shaped internally and graduated on its
upper surface (level graduation), fixed into a metal holder and fitted with adjusting screws
Note 1 to entry: Tubular level is often built and used for high precision levelling in the direction of the tube.
3.2.16.2.1 3.2.16.2.1
coincidence level
coincidence bubble
split bubble-level
tubular level (3.2.16.2(3.2.16.2)) which is observed through a coincidence prism and levelled when the semi-
images of both bubble ends coincide
3.2.16.2.2 3.2.16.2.2
index level
tubular level (3.2.16.2(3.2.16.2)) which is used to ensure that the vertical index (3.2.45(3.2.45)) of a vertical
angle reading is correctly positioned in relation to the plumb line
Note 1 to entry: Normally, a coincidence level (3.2.16.2.1(3.2.16.2.1)) is used.
3.2.16.2.3 3.2.16.2.3
telescope level
tubular level (3.2.16.2(3.2.16.2)) which is securely fixed to the telescope (3.2.38(3.2.38)) parallel to the
collimation axis of the latter to align the telescope to the horizon
Note 1 to entry: Normally, a coincidence level (3.2.16.2.1(3.2.16.2.1)) is used.
3.2.16.3 3.2.16.3
electronic level
level which senses the inclination in sighting- and/or cross-direction by the use of opto-electronic components
such as a light source and a code pattern
Note 1 to entry: Opto-electronic devices with a light source and code pattern to measure the inclination supersede other
principles such as the measurement of the electrical resistance or of the static electrical capacity.
Note 2 to entry: For the realization as stand-alone instrument, see inclinometer (3.1.10.3(3.1.10.3).).
3.2.17 3.2.17
light source
essential element of the electro-optical distance meter (3.1.3(3.1.3),), which produces and emits the energy for
the measuring signal
Note 1 to entry: The light source emits the energy as an electromagnetic wave. It carries the measuring signal which is
normally obtained by modulation of the emitted wave. The light sources mainly used are the solid laser or collimated
LED.
3.2.18 3.2.18
limb
center part
central part
limbus
middle part
integrated group of parts of the theodolite (3.1.19(3.1.19),), or total station (3.1.20(3.1.20),), comprising the
horizontal circle and other elements, permitting the limb to rotate on the vertical axis (3.2.44(3.2.44))
Note 1 to entry: See also base part (3.2.2(3.2.2)) and upper part (3.2.42(3.2.42).).
Note 2 to entry: The limb of electronic theodolites (3.1.19.2(3.1.19.2)) or total stations (3.1.20(3.1.20)) does not usually
rotate around the vertical axes (3.2.44(3.2.44)) since any angle can be set electronically to a certain direction.
3.2.19 3.2.19
modulator
electronic device of the phase shift distanceshiftdistance meter (3.1.3.1(3.1.3.1)) which modulates the carrier
wave
3.2.20 3.2.20
objective
objective lens
combination of several lenses in a common mounting which, together with the focusing lens, projects a real
reversed image of the object in the image plane
Note 1 to entry: The image can be brought into an upright position by means of an inverting prism system.
3.2.21 3.2.21
objective prism
wedge prism
thin prism in front of the objective (3.2.20(3.2.20)) to deviate the line of sight perpendicular to the optical axis
of the telescope
3.2.22 3.2.22
oscillator
electronic device of electro-optical distance met
...