1、Designation: E2544 11Standard Terminology forThree-Dimensional (3D) Imaging Systems1This standard is issued under the fixed designation E2544; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in p
2、arentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This terminology contains common terms, definitions ofterms, descriptions of terms, nomenclature, and acronymsassociated with three-dimensional (3
3、D) imaging systems in aneffort to standardize terminology used for 3D imaging systems.1.2 The definitions of the terms presented in 3.1 are ob-tained from various standard documents developed by variousstandards development organizations. The intent is not tochange these universally accepted definit
4、ions but to gather, ina single document, terms and their definitions that may be usedin current or future standards for 3D imaging systems.1.2.1 In some cases, definitions of the same term from twostandards have been presented to provide additional reference.The text in parentheses to the right of e
5、ach defined term is thename (and, in some cases, the specific section) of the source ofthe definition associated with that term.1.3 The definitions in 3.2 are specific terms developed bythis committee for 3D imaging systems. Some terms may havegenerally accepted definitions in a particular community
6、 or aredefined in existing standards. If there are conflicting defini-tions, our preference is to adapt (modify) the ISO standard (ifavailable) for this standard.1.4 A definition in this terminology is a statement of themeaning of a word or word group expressed in a singlesentence with additional in
7、formation included in notes ordiscussions.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulator
8、y limitations prior to use.NOTE 1The subcommittee responsible for this standard will reviewdefinitions on a five-year basis to determine if the definition is stillappropriate as stated. Revisions will be made when determined necessary.2. Referenced Documents2.1 ASTM Standards:2E456 Terminology Relat
9、ing to Quality and Statistics2.2 ASME Standard:3B89.4.19 Performance Evaluation of Laser Based SphericalCoordinate Measurement Systems2.3 ISO Standard:4VIM International vocabulary of metrology - Basic andgeneral concepts and associated termsISO 111461 Lasers and laser-related equipment Testmethods
10、for laser beam widths, divergence angles andbeam propagation ratios Part 1: Stigmatic and simpleastigmatic beams2.4 NIST/SEMATECH Standard:5NIST/SEMATECH e-Handbook of Statistical Methods3. Terminology3.1 Definitions:accuracy of measurement, ncloseness of the agreementbetween the result of a measure
11、ment and a true value of themeasurand. (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), nsystematic error of theindication of a measuring instrument. (VIM 3.25)DISCUSSION1This terminology is under th
12、e jurisdiction of Committee E57 on 3D ImagingSystems and is the direct responsibility of Subcommittee E57.01 on Terminology.Current edition approved April 1, 2011. Published May 2011. Originallyapproved in 2007. Last previous edition approved in 2010 as E2544 10. DOI:10.1520/E2544-11.2For referenced
13、 ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Society of Mechanical Engineers (ASME), ASMEInterna
14、tional Headquarters, Three Park Ave., New York, NY 10016-5990, http:/www.asme.org.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.5Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop
15、1070, Gaithersburg, MD 20899-1070, http:/www.nist.gov.e-Handbook available at http:/www.itl.nist.gov/div898/handbook/.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.(1) The bias of a measuring instrument is normallyestimated by aver
16、aging the error of indication over an appro-priate number of repeated measurements.bias, ndifference between the average or expected value of adistribution and the true value.(NIST/SEMATECH e-Handbook)DISCUSSION(1) In metrology, the difference between precision andaccuracy is that measures of precis
17、ion are not affected by bias,whereas accuracy measures degrade as bias increases.calibration, nset of operations that establish, under specifiedconditions, the relationship between values of quantitiesindicated by a measuring instrument or measuring system, orvalues represented by a material measure
18、 or a referencematerial, and the corresponding values realized by standards.(VIM 6.11)DISCUSSION(1) The result of a calibration permits either the assignmentof values of measurands to the indications or the determinationof corrections with respect to indications.(2) A calibration may also determine
19、other metrologicalproperties such as the effect of influence quantities.(3) The result of a calibration may be recorded in adocument, sometimes called a calibration certificate or acalibration pensation, nthe process of determining systematic er-rors in an instrument and then applying these values i
20、n anerror model that seeks to eliminate or minimize measure-ment errors. (ASME B89.4.19)conventional true value (of a quantity), nvalue attributedto a particular quantity and accepted, sometimes by conven-tion, as having an uncertainty appropriate for a givenpurpose. (VIM 1.20)DISCUSSION(1) Examples
21、: (1) at a given location, the value assigned tothe quantity realized by a reference standard may be taken asa conventional true value and (2) the CODATA (1986) recom-mended value for the Avogadro constant, NA: 6 022 136 7 31023mol-1.(2) Conventional true value is sometimes called assignedvalue, bes
22、t estimate of the value, conventional value, orreference value.(3) Frequently, a number of results of measurements of aquantity is used to establish a conventional true value.error (of measurement), nresult of a measurement minus atrue value of the measurand. (VIM 3.10)DISCUSSION(1) Since a true val
23、ue cannot be determined, in practice, aconventional true value is used (see true value and conven-tional true value).(2) When it is necessary to distinguish “error” from “relative error,” the former is sometimes called “absolute errorof measurement.” This should not be confused with the “absolute va
24、lue of error,” which is the modulus of error.indicating (measuring) instrument, nmeasuring instru-ment that displays an indication. (VIM 4.6)DISCUSSION(1) Examples include analog indicating voltmeter, digitalfrequency meter, and micrometer.(2) The display may be analog (continuous or discontinu-ous)
25、 or digital.(3) Values of more than one quantity may be displayedsimultaneously.(4) A displaying measuring instrument may also provide arecord.limiting conditions, nthe manufacturers specified limits onthe environmental, utility, and other conditions within whichan instrument may be operated safely
26、and without damage.(ASME B89.4.19)DISCUSSION(1) The manufacturers performance specifications are notassured over the limiting conditions.maximum permissible error (MPE), nextreme values of anerror permitted by specification, regulations, and so forth fora given measuring instrument. (VIM 5.21)measur
27、and, nparticular quantity subject to measurement.(VIM 2.6)DISCUSSION(1) Example includes vapor pressure of a given sample ofwater at 20C.(2) The specification of a measurand may require state-ments about quantities such as time, temperature, and pressure.precision, ncloseness of agreement between in
28、dependenttest results obtained under stipulated conditions.(ASTM E456)DISCUSSION(1) Precision depends on random errors and does not relateto the true value or the specified value.(2) The measure of precision is usually expressed in termsof imprecision and computed as a standard deviation of the test
29、results. Less precision is reflected by a larger standard devia-tion.(3) “Independent test results” means results obtained in amanner not influenced by any previous result on the same orsimilar test object. Quantitative measures of precision dependcritically on the stipulated conditions. Repeatabili
30、ty and repro-ducibility conditions are particular sets of extreme stipulatedconditions.precision, nin metrology, the variability of a measurementprocess around its average value.(NIST/SEMATECH e-Handbook)DISCUSSION(1) Precision is usually distinguished from accuracy, thevariability of a measurement
31、process around the true value.Precision, in turn, can be decomposed further into short-termvariation or repeatability and long-term variation or reproduc-ibility.E2544 112random error, nresult of a measurement minus the meanthat would result from an infinite number of measurementsof the same measura
32、nd carried out under repeatabilityconditions. (VIM 3.13)DISCUSSION(1) Random error is equal to error minus systematic error.(2) Because only a finite number of measurements can bemade, it is possible to determine only an estimate of randomerror.rated conditions, nmanufacturer-specified limits on env
33、i-ronmental, utility, and other conditions within which themanufacturers performance specifications are guaranteed atthe time of installation of the instrument.(ASME B89.4.19)relative error, nerror of measurement divided by a truevalue of the measurand. (VIM 3.12)DISCUSSION(1) Since a true value can
34、not be determined, in practice aconventional true value is used.repeatability (of results of measurements), ncloseness ofthe agreement between the results of successive measure-ments of the same measurand carried out under the sameconditions of measurement. (VIM 3.6)DISCUSSION(1) These conditions ar
35、e called repeatability conditions.(2) Repeatability conditions include: the same measure-ment procedure; the same observer; the same measuringinstrument used under the same conditions; the same location;and repetition over a short period of time.(3) Repeatability may be expressed quantitatively in t
36、ermsof the dispersion characteristics of the results.reproducibility (of results of measurements), nclosenessof the agreement between the results of measurements of thesame measurand carried out under changed conditions ofmeasurement. (VIM 3.7)DISCUSSION(1) A value statement of reproducibility requi
37、res specifica-tion of the conditions changed.(2) The changed conditions may include: principle ofmeasurement; method of measurement; observer; measuringinstrument; reference standard; location; conditions of use; andtime.(3) Reproducibility may be expressed quantitatively interms of the dispersion c
38、haracteristics of the results.(4) Results are usually understood to be corrected results.systematic error, nmean that would result from an infinitenumber of measurements of the same measurand carried outunder repeatability conditions minus a true value of themeasurand. (VIM 3.14)DISCUSSION(1) System
39、atic error is equal to error minus random error.(2) Like true value, systematic error and its causes cannotbe completely known.(3) For a measuring instrument, see “bias.”true value (of a quantity), nvalue consistent with thedefinition of a given particular quantity. (VIM 1.19)DISCUSSION(1) This is a
40、 value that would be obtained by a perfectmeasurement.(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 theremay be many values consistent with the definition of a givenparticular quanti
41、ty.uncertainty of measurement, nparameter, associated withthe result of a measurement, that characterizes the dispersionof the values that could reasonably be attributed to themeasurand. (VIM 3.9)DISCUSSION(1) The parameter may be, for example, a standard devia-tion (or a given multiple of it) or th
42、e half width of an intervalhaving a stated level of confidence.(2) Uncertainty of measurement comprises, in general,many components. Some of these components may be evalu-ated from the statistical distribution of the results of series ofmeasurements and can be characterized by experimental stan-dard
43、 deviations. The other components, which can also becharacterized by standard deviations, are evaluated from as-sumed probability distributions based on experience or otherinformation.(3) It is understood that the result of the measurement is thebest estimate of the value of the measurand, and that
44、allcomponents of uncertainty, including those arising from sys-tematic effects, such as components associated with correctionsand reference standards, contribute to the dispersion.3.2 Definitions of Terms Specific to This Standard:3D imaging system, na non-contact measurement instru-ment used to pro
45、duce a 3D representation (for example, apoint cloud) of an object or a site.DISCUSSION(1) Some examples of a 3D imaging system are laserscanners (also known as LADARs or LIDARs or laser radars),optical range cameras (also known as flash LIDARs or 3Drange cameras), triangulation-based systems such as
46、 thoseusing pattern projectors or lasers, and other systems based oninterferometry.(2) In general, the information gathered by a 3D imagingsystem is a collection of n-tuples, where each n-tuple caninclude but is not limited to spherical or Cartesian coordinates,return signal strength, color, time st
47、amp, identifier, polariza-tion, and multiple range returns.(3) 3D imaging systems are used to measure from rela-tively small scale objects (for example, coin, statue, manufac-tured part, human body) to larger scale objects or sites (forexample, terrain features, buildings, bridges, dams, towns,arche
48、ological sites).E2544 113angular increment, nthe angle, Da, between reportedpoints, where Da = ai ai-1, in either the azimuth orelevation directions (or a combination of both) with respectto the instruments internal frame of reference.DISCUSSION(1) For scanning instruments, the angular increment may
49、also be known as the angle step size.beam diameter (ds), nfor a laser beam with a circularirradiance pattern, the beam diameter is the extent of theirradiance distribution in a cross section of the laser beam (ina plane orthogonal to its propagation path) at a distance z andis given by:dsz! 5 4sz!where:s(z) = sx(z) = sy(z)sx(z),sy(z) = the square roots of the second order mo-mentsDISCUSSION(1) Reference ISO 111461.(2) For a laser beam with a Gaussian distribution ofirradiance, the beam diameter is often def
