ASTM E2544-11a(2019)
(Terminology)Standard Terminology for Three-Dimensional (3D) Imaging Systems
Standard Terminology for Three-Dimensional (3D) Imaging Systems
SCOPE
1.1 This terminology contains common terms, definitions of terms, descriptions of terms, nomenclature, and acronyms associated with three-dimensional (3D) imaging systems in an effort to standardize terminology used for 3D imaging systems.
1.2 The definitions of the terms presented in 3.1 are obtained from various standard documents developed by various standards development organizations. The intent is not to change these universally accepted definitions but to gather, in a single document, terms and their definitions that may be used in current or future standards for 3D imaging systems.
1.2.1 In some cases, definitions of the same term from two standards have been presented to provide additional reference. The text in parentheses to the right of each defined term is the name (and, in some cases, the specific section) of the source of the definition associated with that term.
1.3 The definitions in 3.2 are specific terms developed by this committee for 3D imaging systems. Some terms may have generally accepted definitions in a particular community or are defined in existing standards. If there are conflicting definitions, our preference is to adapt (modify) the ISO standard (if available) for this standard.
1.4 A definition in this terminology is a statement of the meaning of a word or word group expressed in a single sentence with additional information included in notes or discussions.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
Note 1: The subcommittee responsible for this standard will review definitions on a five-year basis to determine if the definition is still appropriate as stated. Revisions will be made when determined necessary.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
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Designation: E2544 − 11a (Reapproved 2019)
Standard Terminology for
Three-Dimensional (3D) Imaging Systems
This standard is issued under the fixed designation E2544; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
1.1 Thisterminologycontainscommonterms,definitionsof
mendations issued by the World Trade Organization Technical
terms, descriptions of terms, nomenclature, and acronyms
Barriers to Trade (TBT) Committee.
associated with three-dimensional (3D) imaging systems in an
efforttostandardizeterminologyusedfor3Dimagingsystems.
2. Referenced Documents
1.2 The definitions of the terms presented in 3.1 are ob-
2.1 ASTM Standards:
tained from various standard documents developed by various
E456Terminology Relating to Quality and Statistics
standards development organizations. The intent is not to
2.2 ASME Standard:
change these universally accepted definitions but to gather, in
B89.4.19Performance Evaluation of Laser Based Spherical
asingledocument,termsandtheirdefinitionsthatmaybeused
Coordinate Measurement Systems
in current or future standards for 3D imaging systems.
2.3 ISO Standard:
1.2.1 In some cases, definitions of the same term from two
VIMInternational vocabulary of metrology -- Basic and
standards have been presented to provide additional reference.
general concepts and associated terms
The text in parentheses to the right of each defined term is the
ISO 11146–1 Lasers and laser-related equipment — Test
name(and,insomecases,thespecificsection)ofthesourceof
methods for laser beam widths, divergence angles and
the definition associated with that term.
beam propagation ratios — Part 1: Stigmatic and simple
1.3 The definitions in 3.2 are specific terms developed by
astigmatic beams
thiscommitteefor3Dimagingsystems.Sometermsmayhave
2.4 NIST/SEMATECH Standard:
generallyaccepteddefinitionsinaparticularcommunityorare
NIST/SEMATECHe-Handbook of Statistical Methods
defined in existing standards. If there are conflicting
definitions, our preference is to adapt (modify) the ISO
3. Terminology
standard (if available) for this standard.
3.1 Definitions:
1.4 A definition in this terminology is a statement of the
accuracy of measurement, n—closeness of the agreement
meaning of a word or word group expressed in a single
between the result of a measurement and a true value of the
sentence with additional information included in notes or
measurand. (VIM 3.5)
discussions.
DISCUSSION—
(1)Accuracy is a qualitative concept.
1.5 This standard does not purport to address all of the
(2)Theterm“precision”shouldnotbeusedfor“accuracy.”
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
bias (of a measuring instrument), n—systematic error of the
priate safety, health, and environmental practices and deter-
indication of a measuring instrument. (VIM 3.25)
mine the applicability of regulatory limitations prior to use.
DISCUSSION—
NOTE 1—The subcommittee responsible for this standard will review
definitions on a five-year basis to determine if the definition is still
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
appropriateasstated.Revisionswillbemadewhendeterminednecessary.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
1.6 This international standard was developed in accor-
Standards volume information, refer to the standard’s Document Summary page on
dance with internationally recognized principles on standard-
the ASTM website.
Available from American Society of Mechanical Engineers (ASME), ASME
International Headquarters, Three Park Ave., New York, NY 10016-5990, http://
www.asme.org.
1 4
This terminology is under the jurisdiction of Committee E57 on 3D Imaging Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
Systems and is the direct responsibility of Subcommittee E57.01 on Terminology. 4th Floor, New York, NY 10036, http://www.ansi.org.
Current edition approved March 1, 2019. Published March 2019. Originally Available from National Institute of Standards and Technology (NIST), 100
approved in 2007. Last previous edition approved in 2011 as E2544 – 11a. DOI: Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov.
10.1520/E2544-11AR19. e-Handbook available at http://www.itl.nist.gov/div898/handbook/.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2544 − 11a (2019)
DISCUSSION—
(1)The bias of a measuring instrument is normally esti-
(1)Examples include analog indicating voltmeter, digital
mated by averaging the error of indication over an appropriate
frequency meter, and micrometer.
number of repeated measurements.
(2)The display may be analog (continuous or discontinu-
bias, n—differencebetweentheaverageorexpectedvalueofa
ous) or digital.
distribution and the true value.
(3)Values of more than one quantity may be displayed
(NIST/SEMATECH e-Handbook)
simultaneously.
DISCUSSION—
(4)Adisplaying measuring instrument may also provide a
(1)In metrology, the difference between precision and
record.
accuracy is that measures of precision are not affected by bias,
whereas accuracy measures degrade as bias increases.
limiting conditions, n—the manufacturer’s specified limits on
theenvironmental,utility,andotherconditionswithinwhich
calibration, n—setofoperationsthatestablish,underspecified
an instrument may be operated safely and without damage.
conditions, the relationship between values of quantities
(ASME B89.4.19)
indicatedbyameasuringinstrumentormeasuringsystem,or
DISCUSSION—
values represented by a material measure or a reference
(1)The manufacturer’s performance specifications are not
material,andthecorrespondingvaluesrealizedbystandards.
assured over the limiting conditions.
(VIM 6.11)
DISCUSSION— maximum permissible error (MPE), n—extremevaluesofan
(1)Theresultofacalibrationpermitseithertheassignment
errorpermittedbyspecification,regulations,andsoforthfor
ofvaluesofmeasurandstotheindicationsorthedetermination a given measuring instrument. (VIM 5.21)
of corrections with respect to indications.
measurand, n—particular quantity subject to measurement.
(2)A calibration may also determine other metrological
(VIM 2.6)
properties such as the effect of influence quantities.
DISCUSSION—
(3)The result of a calibration may be recorded in a
(1)Example includes vapor pressure of a given sample of
document, sometimes called a calibration certificate or a
water at 20°C.
calibration report.
(2)The specification of a measurand may require state-
compensation, n—the process of determining systematic er- mentsaboutquantitiessuchastime,temperature,andpressure.
rors in an instrument and then applying these values in an
precision, n—closeness of agreement between independent
error model that seeks to eliminate or minimize measure-
test results obtained under stipulated conditions.
ment errors. (ASME B89.4.19)
(ASTM E456)
DISCUSSION—
conventional true value (of a quantity), n—value attributed
(1)Precisiondependsonrandomerrorsanddoesnotrelate
to a particular quantity and accepted, sometimes by
to the true value or the specified value.
convention, as having an uncertainty appropriate for a given
(2)The measure of precision is usually expressed in terms
purpose. (VIM 1.20)
ofimprecisionandcomputedasastandarddeviationofthetest
DISCUSSION—
results. Less precision is reflected by a larger standard devia-
(1)Examples: (1) at a given location, the value assigned to
the quantity realized by a reference standard may be taken as tion.
(3)“Independent test results” means results obtained in a
a conventional true value and (2) the CODATA(1986) recom-
mended value for the Avogadro constant, N : 6 022 136 7 × manner not influenced by any previous result on the same or
A
23 -1
similar test object. Quantitative measures of precision depend
10 mol .
(2)Conventional true value is sometimes called assigned critically on the stipulated conditions. Repeatability and repro-
ducibility conditions are particular sets of extreme stipulated
value, best estimate of the value, conventional value, or
reference value. conditions.
(3)Frequently, a number of results of measurements of a
precision, n—in metrology, the variability of a measurement
quantity is used to establish a conventional true value.
process around its average value.
error (of measurement), n—result of a measurement minus a (NIST/SEMATECH e-Handbook)
true value of the measurand. (VIM 3.10) DISCUSSION—
DISCUSSION— (1)Precision is usually distinguished from accuracy, the
(1)Since a true value cannot be determined, in practice, a variability of a measurement process around the true value.
conventional true value is used (see true value and conven-
Precision, in turn, can be decomposed further into short-term
tional true value). variation or repeatability and long-term variation or reproduc-
(2)When it is necessary to distinguish “error” from “ ibility.
relative error,” the former is sometimes called “absolute error
random error, n—result of a measurement minus the mean
of measurement.” This should not be confused with the “
that would result from an infinite number of measurements
absolute value of error,” which is the modulus of error.
of the same measurand carried out under repeatability
indicating (measuring) instrument, n—measuringinstrument conditions. (VIM 3.13)
that displays an indication. (VIM 4.6) DISCUSSION—
E2544 − 11a (2019)
(1)Random error is equal to error minus systematic error. (1)This is a value that would be obtained by a perfect
(2)Because only a finite number of measurements can be measurement.
made, it is possible to determine only an estimate of random (2)True values are by nature indeterminate.
error. (3)Theindefinitearticle“a,”ratherthanthedefinitearticle
“the,” is used in conjunction with “true value” because there
rated conditions, n—manufacturer-specified limits on
may be many values consistent with the definition of a given
environmental,utility,andotherconditionswithinwhichthe
particular quantity.
manufacturer’s performance specifications are guaranteed at
the time of installation of the instrument. uncertainty of measurement, n—parameter, associated with
(ASME B89.4.19) theresultofameasurement,thatcharacterizesthedispersion
of the values that could reasonably be attributed to the
relative error, n—error of measurement divided by a true
measurand. (VIM 3.9)
value of the measurand. (VIM 3.12)
DISCUSSION—
DISCUSSION—
(1)The parameter may be, for example, a standard devia-
(1)Since a true value cannot be determined, in practice a
tion (or a given multiple of it) or the half width of an interval
conventional true value is used.
having a stated level of confidence.
(2)Uncertainty of measurement comprises, in general,
repeatability (of results of measurements), n—closeness of
many components. Some of these components may be evalu-
the agreement between the results of successive measure-
ated from the statistical distribution of the results of series of
ments of the same measurand carried out under the same
measurements and can be characterized by experimental stan-
conditions of measurement. (VIM 3.6)
dard deviations. The other components, which can also be
DISCUSSION—
characterized by standard deviations, are evaluated from as-
(1)These conditions are called repeatability conditions.
sumed probability distributions based on experience or other
(2)Repeatability conditions include: the same measure-
information.
ment procedure; the same observer; the same measuring
(3)Itisunderstoodthattheresultofthemeasurementisthe
instrument used under the same conditions; the same location;
best estimate of the value of the measurand, and that all
and repetition over a short period of time.
components of uncertainty, including those arising from sys-
(3)Repeatability may be expressed quantitatively in terms
tematiceffects,suchascomponentsassociatedwithcorrections
of the dispersion characteristics of the results.
and reference standards, contribute to the dispersion.
reproducibility (of results of measurements), n—closeness
3.2 Definitions of Terms Specific to This Standard:
oftheagreementbetweentheresultsofmeasurementsofthe
3D imaging system, n—a non-contact measurement instru-
same measurand carried out under changed conditions of
ment used to produce a 3D representation (for example, a
measurement. (VIM 3.7)
point cloud) of an object or a site.
DISCUSSION—
DISCUSSION—
(1)Avalue statement of reproducibility requires specifica-
(1)Some examples of a 3D imaging system are laser
tion of the conditions changed.
scanners (also known as LADARs or LIDARs or laser radars),
(2)The changed conditions may include: principle of
optical range cameras (also known as flash LIDARs or 3D
measurement; method of measurement; observer; measuring
range cameras), triangulation-based systems such as those
instrument;referencestandard;location;conditionsofuse;and
using pattern projectors or lasers, and other systems based on
time.
interferometry.
(3)Reproducibility may be expressed quantitatively in
(2)In general, the information gathered by a 3D imaging
terms of the dispersion characteristics of the results.
system is a collection of n-tuples, where each n-tuple can
(4)Results are usually understood to be corrected results.
includebutisnotlimitedtosphericalorCartesiancoordinates,
return signal strength, color, time stamp, identifier,
systematic error, n—mean that would result from an infinite
number of measurements of the same measurand carried out polarization, and multiple range returns.
(3)3D imaging systems are used to measure from rela-
under repeatability conditions minus a true value of the
measurand. (VIM 3.14) tively small scale objects (for example, coin, statue, manufac-
tured part, human body) to larger scale objects or sites (for
DISCUSSION—
(1)Systematic error is equal to error minus random error. example, terrain features, buildings, bridges, dams, towns,
(2)Like true value, systematic error and its causes cannot archeological sites).
be completely known.
angular increment, n—the angle, ∆α, between reported
(3)For a measuring instrument, see “bias.”
points, where ∆α = α – α , in either the azimuth or
i i-1
true value (of a quantity), n—value consistent with the elevation directions (or a combination of both) with respect
definition of a given particular quantity. (V
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2544 − 11a E2544 − 11a (Reapproved 2019)
Standard Terminology for
Three-Dimensional (3D) Imaging Systems
This standard is issued under the fixed designation E2544; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This terminology contains common terms, definitions of terms, descriptions of terms, nomenclature, and acronyms
associated with three-dimensional (3D) imaging systems in an effort to standardize terminology used for 3D imaging systems.
1.2 The definitions of the terms presented in 3.1 are obtained from various standard documents developed by various standards
development organizations. The intent is not to change these universally accepted definitions but to gather, in a single document,
terms and their definitions that may be used in current or future standards for 3D imaging systems.
1.2.1 In some cases, definitions of the same term from two standards have been presented to provide additional reference. The
text in parentheses to the right of each defined term is the name (and, in some cases, the specific section) of the source of the
definition associated with that term.
1.3 The definitions in 3.2 are specific terms developed by this committee for 3D imaging systems. Some terms may have
generally accepted definitions in a particular community or are defined in existing standards. If there are conflicting definitions,
our preference is to adapt (modify) the ISO standard (if available) for this standard.
1.4 A definition in this terminology is a statement of the meaning of a word or word group expressed in a single sentence with
additional information included in notes or discussions.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
NOTE 1—The subcommittee responsible for this standard will review definitions on a five-year basis to determine if the definition is still appropriate
as stated. Revisions will be made when determined necessary.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E456 Terminology Relating to Quality and Statistics
2.2 ASME Standard:
B89.4.19 Performance Evaluation of Laser Based Spherical Coordinate Measurement Systems
2.3 ISO Standard:
VIM International vocabulary of metrology -- Basic and general concepts and associated terms
ISO 11146–1 Lasers and laser-related equipment — Test methods for laser beam widths, divergence angles and beam
propagation ratios — Part 1: Stigmatic and simple astigmatic beams
2.4 NIST/SEMATECH Standard:
NIST/SEMATECH e-Handbook of Statistical Methods
This terminology is under the jurisdiction of Committee E57 on 3D Imaging Systems and is the direct responsibility of Subcommittee E57.01 on Terminology.
Current edition approved May 15, 2011March 1, 2019. Published June 2011March 2019. Originally approved in 2007. Last previous edition approved in 201102011 as
E2544 – 11.11a. DOI: 10.1520/E2544-11A.10.1520/E2544-11AR19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, Three Park Ave., New York, NY 10016-5990, http://
www.asme.org.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov. e-Handbook
available at http://www.itl.nist.gov/div898/handbook/.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2544 − 11a (2019)
3. Terminology
3.1 Definitions:
accuracy of measurement, n—closeness of the agreement between the result of a measurement and a true value of the measurand.
(VIM 3.5)
DISCUSSION—
(1) Accuracy is a qualitative concept.
(2) The term “precision” should not be used for “accuracy.”
bias (of a measuring instrument), n—systematic error of the indication of a measuring instrument. (VIM 3.25)
DISCUSSION—
(1) The bias of a measuring instrument is normally estimated by averaging the error of indication over an appropriate number
of repeated measurements.
bias, n—difference between the average or expected value of a distribution and the true value.
(NIST/SEMATECH e-Handbook)
DISCUSSION—
(1) In metrology, the difference between precision and accuracy is that measures of precision are not affected by bias, whereas
accuracy measures degrade as bias increases.
calibration, n—set of operations that establish, under specified conditions, the relationship between values of quantities indicated
by a measuring instrument or measuring system, or values represented by a material measure or a reference material, and the
corresponding values realized by standards. (VIM 6.11)
DISCUSSION—
(1) The result of a calibration permits either the assignment of values of measurands to the indications or the determination
of corrections with respect to indications.
(2) A calibration may also determine other metrological properties such as the effect of influence quantities.
(3) The result of a calibration may be recorded in a document, sometimes called a calibration certificate or a calibration report.
compensation, n—the process of determining systematic errors in an instrument and then applying these values in an error model
that seeks to eliminate or minimize measurement errors. (ASME B89.4.19)
conventional true value (of a quantity), n—value attributed to a particular quantity and accepted, sometimes by convention, as
having an uncertainty appropriate for a given purpose. (VIM 1.20)
DISCUSSION—
(1) Examples: (1) at a given location, the value assigned to the quantity realized by a reference standard may be taken as a
23 -1
conventional true value and (2) the CODATA (1986) recommended value for the Avogadro constant, N : 6 022 136 7 × 10 mol .
A
(2) Conventional true value is sometimes called assigned value, best estimate of the value, conventional value, or reference
value.
(3) Frequently, a number of results of measurements of a quantity is used to establish a conventional true value.
error (of measurement), n—result of a measurement minus a true value of the measurand. (VIM 3.10)
DISCUSSION—
(1) Since a true value cannot be determined, in practice, a conventional true value is used (see true value and conventional true
value).
(2) When it is necessary to distinguish “error” from “ relative error,” the former is sometimes called “absolute error of
measurement.” This should not be confused with the “ absolute value of error,” which is the modulus of error.
indicating (measuring) instrument, n—measuring instrument that displays an indication. (VIM 4.6)
DISCUSSION—
(1) Examples include analog indicating voltmeter, digital frequency meter, and micrometer.
(2) The display may be analog (continuous or discontinuous) or digital.
(3) Values of more than one quantity may be displayed simultaneously.
(4) A displaying measuring instrument may also provide a record.
limiting conditions, n—the manufacturer’s specified limits on the environmental, utility, and other conditions within which an
instrument may be operated safely and without damage. (ASME B89.4.19)
DISCUSSION—
(1) The manufacturer’s performance specifications are not assured over the limiting conditions.
maximum permissible error (MPE), n—extreme values of an error permitted by specification, regulations, and so forth for a
given measuring instrument. (VIM 5.21)
measurand, n—particular quantity subject to measurement. (VIM 2.6)
DISCUSSION—
E2544 − 11a (2019)
(1) Example includes vapor pressure of a given sample of water at 20°C.
(2) The specification of a measurand may require statements about quantities such as time, temperature, and pressure.
precision, n—closeness of agreement between independent test results obtained under stipulated conditions.
(ASTM E456)
DISCUSSION—
(1) Precision depends on random errors and does not relate to the true value or the specified value.
(2) The measure of precision is usually expressed in terms of imprecision and computed as a standard deviation of the test
results. Less precision is reflected by a larger standard deviation.
(3) “Independent test results” means results obtained in a manner not influenced by any previous result on the same or similar
test object. Quantitative measures of precision depend critically on the stipulated conditions. Repeatability and reproducibility
conditions are particular sets of extreme stipulated conditions.
precision, n—in metrology, the variability of a measurement process around its average value.
(NIST/SEMATECH e-Handbook)
DISCUSSION—
(1) Precision is usually distinguished from accuracy, the variability of a measurement process around the true value. Precision,
in turn, can be decomposed further into short-term variation or repeatability and long-term variation or reproducibility.
random error, n—result of a measurement minus the mean that would result from an infinite number of measurements of the same
measurand carried out under repeatability conditions. (VIM 3.13)
DISCUSSION—
(1) Random error is equal to error minus systematic error.
(2) Because only a finite number of measurements can be made, it is possible to determine only an estimate of random error.
rated conditions, n—manufacturer-specified limits on environmental, utility, and other conditions within which the manufacturer’s
performance specifications are guaranteed at the time of installation of the instrument.
(ASME B89.4.19)
relative error, n—error of measurement divided by a true value of the measurand. (VIM 3.12)
DISCUSSION—
(1) Since a true value cannot be determined, in practice a conventional true value is used.
repeatability (of results of measurements), n—closeness of the agreement between the results of successive measurements of the
same measurand carried out under the same conditions of measurement. (VIM 3.6)
DISCUSSION—
(1) These conditions are called repeatability conditions.
(2) Repeatability conditions include: the same measurement procedure; the same observer; the same measuring instrument used
under the same conditions; the same location; and repetition over a short period of time.
(3) Repeatability may be expressed quantitatively in terms of the dispersion characteristics of the results.
reproducibility (of results of measurements), n—closeness of the agreement between the results of measurements of the same
measurand carried out under changed conditions of measurement. (VIM 3.7)
DISCUSSION—
(1) A value statement of reproducibility requires specification of the conditions changed.
(2) The changed conditions may include: principle of measurement; method of measurement; observer; measuring instrument;
reference standard; location; conditions of use; and time.
(3) Reproducibility may be expressed quantitatively in terms of the dispersion characteristics of the results.
(4) Results are usually understood to be corrected results.
systematic error, n—mean that would result from an infinite number of measurements of the same measurand carried out under
repeatability conditions minus a true value of the measurand. (VIM 3.14)
DISCUSSION—
(1) Systematic error is equal to error minus random error.
(2) Like true value, systematic error and its causes cannot be completely known.
(3) For a measuring instrument, see “bias.”
true value (of a quantity), n—value consistent with the definition of a given particular quantity. (VIM 1.19)
DISCUSSION—
(1) This is a value that would be obtained by a perfect measurement.
(2) True values are by nature indeterminate.
(3) The indefinite article “a,” rather than the definite article “the,” is used in conjunction with “true value” because there may
be many values consistent with the definition of a given particular quantity.
E2544 − 11a (2019)
uncertainty of measurement, n—parameter, associated with the result of a measurement, that characterizes the dispersion of the
values that could reasonably be attributed to the measurand. (VIM 3.9)
DISCUSSION—
(1) The parameter may be, for example, a standard deviation (or a given multiple of it) or the half width of an interval having
a stated level of confidence.
(2) Uncertainty of measurement comprises, in general, many components. Some of these components may be evaluated from
the statistical distribution of the results of series of measurements and can be characterized by experimental standard deviations.
The other components, which can also be characterized by standard deviations, are evaluated from assumed probability
distributions based on experience or other information.
(3) It is understood that the result of the measurement is the best estimate of the value of the measurand, and that all
components of uncertainty, including those arising from systematic effects, such as components associated with corrections and
reference standards, contribute to the dispersion.
3.2 Definitions of Terms Specific to This Standard:
3D imaging system, n—a non-contact measurement instrument used to produce a 3D representation (for example, a point cloud)
of an object or a site.
DISCUSSION—
(1) Some examples of a 3D imaging system are laser scanners (also known as LADARs or LIDARs or laser radars), optical
range cameras (also known as flash LIDARs or 3D range cameras), triangulation-based systems such as those using pattern
projectors or lasers, and other systems based on interferometry.
(2) In general, the informatio
...
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