ISO 17123-4:2012
(Main)Optics and optical instruments — Field procedures for testing geodetic and surveying instruments — Part 4: Electro-optical distance meters (EDM measurements to reflectors)
Optics and optical instruments — Field procedures for testing geodetic and surveying instruments — Part 4: Electro-optical distance meters (EDM measurements to reflectors)
This part of ISO 17123 specifies field procedures to be adopted when determining and evaluating the precision (repeatability) of electro-optical distance meters (EDM instruments) and their ancillary equipment when used in building and surveying measurements. This part of ISO 17123 is applicable to reflector-type EDM instruments only and is not designed to determine the precision of non-prism EDM types. Primarily, these tests are intended to be field verifications of the suitability of a particular instrument for the immediate task at hand and to satisfy the requirements of other standards. They are not proposed as tests for acceptance or performance evaluations that are more comprehensive in nature. This part of ISO 17123 can be thought of as one of the first steps in the process of evaluating the uncertainty of a measurement (more specifically a measurand). The uncertainty of a result of a measurement is dependent on a number of parameters. Therefore we differentiate between different measures of accuracy and objectives in testing, like repeatability, reproducibility (e.g. between day repeatability), and of course a thorough assessment of all possible error sources, as prescribed by ISO/IEC Guide 98-3 and by ISO 17123-1. These field procedures have been developed specifically for in situ applications without the need for special ancillary equipment and are purposefully designed to minimize atmospheric influences.
Optique et instruments d'optique — Méthodes d'essai sur site des instruments géodésiques et d'observation — Partie 4: Télémètres électro-optiques (mesurages MED avec réflecteurs)
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 17123-4
Second edition
2012-06-01
Optics and optical instruments — Field
procedures for testing geodetic and
surveying instruments —
Part 4:
Electro-optical distance meters (EDM
measurements to reflectors)
Optique et instruments d’optique — Méthodes d’essai sur site des
instruments géodésiques et d’observation —
Partie 4: Télémètres électro-optiques (mesurages MED avec réflecteurs)
Reference number
ISO 17123-4:2012(E)
©
ISO 2012
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ISO 17123-4:2012(E)
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ISO 17123-4:2012(E)
Contents Page
Foreword .iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 General . 2
4.1 Requirements . 2
4.2 Procedure 1: Simplified test procedure . 2
4.3 Procedure 2: Full test procedure (Type A evaluation of standard uncertainty) . 2
5 Simplified test procedure . 3
5.1 Configuration of the test field . 3
5.2 Measurements . 4
5.3 Calculation . 4
5.4 Further investigations . 4
6 Full test procedure . 5
6.1 Configuration of the test line. 5
6.2 Measurements . 6
6.3 Calculation . 7
6.4 Statistical tests .10
6.5 Combined standard uncertainty evaluation (Type A and Type B) .12
Annex A (informative) Example of the simplified test procedure .13
Annex B (informative) Example of the full test procedure .15
Annex C (informative) Example for the calculation of a combined uncertainty budget (Type A and
Type B) .19
Bibliography .22
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ISO 17123-4:2012(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17123-4 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 6,
Geodetic and surveying instruments.
This second edition cancels and replaces the first edition (ISO 17123-4:2001), which has been technically revised.
ISO 17123 consists of the following parts, under the general title Optics and optical instruments —
Field procedures for testing geodetic and surveying instruments:
— Part 1: Theory
— Part 2: Levels
— Part 3: Theodolites
— Part 4: Electro-optical distance meters (EDM measurements to reflectors)
— Part 5: Total stations
— Part 6: Rotating lasers
— Part 7: Optical plumbing instruments
— Part 8 : GNSS field measurement systems in real-time kinematic (RTK)
Annexes A, B and C of this part of ISO 17123 are for information only.
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ISO 17123-4:2012(E)
Introduction
This part of ISO 17123 specifies field procedures for adoption when determining and evaluating the uncertainty
of measurement results obtained by geodetic instruments and their ancillary equipment, when used in building
and surveying measuring tasks. Primarily, these tests are intended to be field verifications of suitability of a
particular instrument for the immediate task. They are not proposed as tests for acceptance or performance
evaluations that are more comprehensive in nature.
The definition and concept of uncertainty as a quantitative attribute to the final result of measurement were
developed mainly in the last two decades, even though error analysis has long been a part of all measurement
sciences. After several stages, the CIPM (Comité Internationale des Poids et Mesures) referred the task of
developing a detailed guide to ISO. Under the responsibility of the ISO Technical Advisory Group on Metrology
(TAG 4), and in conjunction with six worldwide metrology organizations, a guidance document on the expression
of measurement uncertainty was compiled with the objective of providing rules for use within standardization,
calibration, laboratory, accreditation and metrology services. ISO/IEC Guide 98-3 was first published as the
Guide to the Expression of Uncertainty in Measurement (GUM) in 1995.
With the introduction of uncertainty in measurement in ISO 17123 (all parts), it is intended to finally provide a
uniform, quantitative expression of measurement uncertainty in geodetic metrology with the aim of meeting the
requirements of customers.
ISO 17123 (all parts) provides not only a means of evaluating the precision (experimental standard deviation)
of an instrument, but also a tool for defining an uncertainty budget, which allows for the summation of all
uncertainty components, whether they are random or systematic, to a representative measure of accuracy, i.e.
the combined standard uncertainty.
ISO 17123 (all parts) therefore provides, for each instrument investigated by the procedures, a proposal
for additional, typical influence quantities, which can be expected during practical use. The customer can
estimate, for a specific application, the relevant standard uncertainty components in order to derive and state
the uncertainty of the measuring result.
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INTERNATIONAL STANDARD ISO 17123-4:2012(E)
Optics and optical instruments — Field procedures for testing
geodetic and surveying instruments —
Part 4:
Electro-optical distance meters (EDM measurements to reflectors)
1 Scope
This part of ISO 17123 specifies field procedures to be adopted when determining and evaluating the precision
(repeatability) of electro-optical distance meters (EDM instruments) and their ancillary equipment when used in
building and surveying measurements. This part of ISO 17123 is applicable to reflector-type EDM instruments
only and is not designed to determine the precision of non-prism EDM types. Primarily, these tests are intended
to be field verifications of the suitability of a particular instrument for the immediate task at hand and to satisfy
the requirements of other standards. They are not proposed as tests for acceptance or performance evaluations
that are more comprehensive in nature.
This part of ISO 17123 can be thought of as one of the first steps in the process of evaluating the uncertainty of
a measurement (more specifically a measurand). The uncertainty of a result of a measurement is dependent on
a number of parameters. Therefore we differentiate between different measures of accuracy and objectives in
testing, like repeatability, reproducibility (e.g. between day repeatability), and of course a thorough assessment
of all possible error sources, as prescribed by ISO/IEC Guide 98-3 and by ISO 17123-1.
These field procedures have been developed specifically for in situ applications without the need for special
ancillary equipment and are purposefully designed to minimize atmospheric influences.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced document
(including any amendments) applies.
ISO 3534-1, Statistics — Vocabulary and symbols — Part 1: General statistical terms and terms used in probability
ISO 4463-1, Measurement methods for building — Setting-out and measurement — Part 1: Planning and
organization, measuring procedures, acceptance criteria
ISO 7077, Measuring methods for building — General principles and procedures for the verification of
dimensional compliance
ISO 7078, Building construction — Procedures for setting out, measurement and surveying — Vocabulary and
guidance notes
ISO 9849, Optics and optical instruments — Geodetic and surveying instruments — Vocabulary
ISO 17123-1, Optics and optical instruments — Field procedures for testing geodetic and surveying
instruments — Part 1: Theory
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
ISO/IEC Guide 99, International vocabulary of metrology – Basic and general concepts and associated terms (VIM)
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ISO 17123-4:2012(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4463-1, ISO 7077, ISO 7078,
ISO 9849, ISO 17123-1, ISO/IEC Guide 98-3 and ISO/IEC Guide 99 apply.
4 General
4.1 Requirements
Before commencing surveying, it is important that the operator investigates that the precision in use of the
measuring equipment is appropriate to the intended measuring task.
The EDM instrument and its ancillary equipment shall be in known and acceptable states of permanent
adjustment according to the methods specified in the manufacturer’s handbook, and used with tripods, forced
centring equipment and reflectors as recommended by the manufacturer.
The results of these tests are influenced by meteorological conditions. These conditions will include variations in
air temperature and air pressure. Actual meteorological data shall be measured in order to derive atmospheric
corrections, which shall be added to the raw distances. The particular conditions to be taken into account may
vary, depending on the location where the tasks are to be undertaken. These conditions shall include variations
in air temperature, wind speed, degree of cloudiness and visibility. Note should also be taken of the actual
weather conditions at the time of measurement and the type of surface above which the measurements are
made. The conditions chosen for the tests should match those expected when the intended measuring task is
actually carried out (see ISO 7077 and ISO 7078).
This part of ISO 17123 describes two different field procedures as given in Clauses 5 and 6. The operator shall
choose the procedure which is most relevant to the project’s particular requirements.
4.2 Procedure 1: Simplified test procedure
The simplified test procedure provides an estimate as to whether the precision of a given EDM equipment is
within the specified permitted deviation according to ISO 4463-1.
The simplified test procedure is based on a limited number of measurements. Therefore, a significant standard
deviation and consequently standard uncertainty cannot be obtained. If a more precise assessment of the
EDM instrument under field conditions is required, it is recommended to adopt the more rigorous full test
procedure as given in Clause 6.
This test procedure relies on having a test field with distances which are accepted as true values. If such a test
field is not available, it is necessary to determine the unknown distances, using an EDM instrument of higher
accuracy than that investigated in this test procedure. If no EDM with higher accuracy is available, the full test
procedure has to be applied.
4.3 Procedure 2: Full test procedure (Type A evaluation of standard uncertainty)
The full test procedure shall be adopted to determine the best achievable measure of precision of a particular
EDM instrument and its ancillary equipment under field conditions, described by the operator.
The full test procedure is based on measurements of distances in all combinations on a test line without
nominal values. The experimental standard deviation of a single distance measurement is determined from a
least squares adjustment of the distances in all combinations. Scale errors of an EDM instrument cannot be
detected by this procedure. But scale errors in general do not have any influence, neither on the experimental
standard deviation, s, nor on the zero-point correction, δ. In order to determine the stability of the scale, the
measuring frequency of the EDM instrument can be checked by means of a frequency meter.
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ISO 17123-4:2012(E)
The test procedure given in Clause 6 is intended for determining the measure of precision in use of a particular
EDM instrument. This measure of precision in use is expressed in terms of the experimental standard deviation,
s, of a single measured distance, which is considered the type A standard uncertainty:
su=
ISO-EDM
Further, this procedure implies:
— the measure of precision in use of EDM instruments by a single survey team with a single instrument and
its ancillary equipment at a given time;
— the measure of precision in use of a single instrument over time;
— the measure of precision in use of each of several EDM instruments in order to enable a comparison of
their respective achievable precisions to be obtained under similar field conditions.
Statistical tests should be applied to determine whether the experimental standard deviation, s, obtained belongs
to the population of the instrumentation’s theoretical standard deviation σ, whether two tested samples belong
to the same population and whether the zero-point correction, δ, is equal to zero or equal to a predetermined
value, δ (see 6.4).
0
5 Simplified test procedure
5.1 Configuration of the test field
The test field shall consist of one permanently marked instrument station and four permanently mounted
reflectors at typical distances for the usual working range of the particular EDM instrument (e.g. from 20 m to
200 m). If permanent mounting of the reflectors is not possible, then the ground points of the reflector stations
should be indelibly marked.
In order to set up the test field, each distance shall be measured and meteorologically corrected at least
three times using a higher accurate EDM instrument (see Figure 1) to eventually obtain a mean value. For
this purpose, air temperature and air pressure have to be measured individually at the instrument and the
target point very thoroughly in order to determine the necessary corrections of the mean values [1 ppm for any
deviation of 1 °C in temperature and/or for any deviation of 3 hPa (3 mbar) in air pressure].
Figure 1 — Configuration of the test field for the simplified test procedure
The atmospherically corrected mean values of the four distances shall be considered to be true values:
xd=
11
xd=
22
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ISO 17123-4:2012(E)
xd=
33
xd=
44
5.2 Measurements
When setting up the EDM instrument, special care shall be taken when centring above the ground point.
Each distance shall be measured three times. Also, the air temperature and the air pressure shall be measured
to derive the atmospheric corrections. The measured distances x , x , x , x are the mean values of the three
1 2 3 4
measurements corrected for atmospheric influences.
5.3 Calculation
All differences xx= shall be within the specified permitted deviation ± p (according to ISO 4463-1) for the
jj
intended measuring task. If p is not given, all differences shall be xx=≤ 25, × s , where s is the standard
jj
uncertainty u of a single distance measurement, according to the full test procedure described in Clause 6.
ISO-EDM
If the differences xx− are too large for the intended task, it is necessary to make further investigations in
jj
order to identify the main sources of errors.
5.4 Further investigations
If all differences xx= have the same sign, then a systematic error is suspected. This can be an error of the
jj
zero-point correction or a scale error. If no source for the systematic error can be recognized, then it is
recommended to carry out the full test procedure as given in Clause 6.
If a scale error is suspected, then the measuring frequency of the EDM instrument should be checked by
means of a frequency meter, or the local service of the EDM manufacturer has to be contacted.
To check the zero-point correction, δ, a temporary baseline (about 50 m) consisting of three points on a straight
line with an in-line tolerance of 3 cm should be established (see Figure 2). Three tripods with forced centring
shall constitute the baseline.
Figure 2 — Temporary baseline to check the zero-point correction
From the measured distances between the tripods, the zero-point correction is calculated
δ =−13,,12−23, (1)
where
δ is the zero-point correction, and
are the measured distances between the three tripods.
13,; 12, and 23,
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ISO 17123-4:2012(E)
6 Full test procedure
6.1 Configuration of the test line
A test configuration between 300 m and 600 m long with seven points on a straight line shall be established.
The total line can also have an appropriate length to the distance of the intended use of the EDM (for line setup,
see Figure 3). The points shall be stable during the test measurements.
Figure 3 — Configuration of the test line for the full test procedure
A: Test line setup with 21 different distances
A good configuration of the
...
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