SIST EN ISO 25178-2:2012

Geometrical product specifications (GPS) - Surface texture: Areal - Part 2: Terms, definitions and surface texture parameters (ISO 25178-2:2012)

This International Standard specifies minimum requirements for instruments and systems that fall into the class of corneal topographers (CTs). It also specifies tests and procedures to verify that a system or instrument complies with this International Standard and thus qualifies as a CT according to this International Standard. It also specifies tests and procedures that allow the verification of capabilities of systems that are beyond the minimum requirements for CTs. This International Standard defines terms that are specific to the characterization of the corneal shape so that they may be standardized throughout the field of vision care. This International Standard is applicable to instruments, systems and methods that are intended to measure the surface shape of the cornea of the human eye.

Geometrische Produktspezifikation (GPS) - Oberflächenbeschaffenheit: Flächenhaft - Teil 2: Begriffe und Oberflächen-Kenngrößen (ISO 25178-2:2012)

Dieser Teil von ISO 25178 legt die Benennungen, Definitionen und Parameter für die Ermittlung der Oberflächenbeschaffenheit durch flächenhafte Verfahren fest.

Spécification géométrique des produits (GPS) - État de surface: surfacique - Partie 2: Termes, définitions et paramètres d'états de surface (ISO 25178-2:2012)

L'ISO 25178:2012 spécifie les termes, définitions et paramètres applicables à la détermination de l'état de surface au moyen de méthodes surfaciques.

Specifikacija geometrijskih veličin izdelka - Tekstura površine: ploskovna - 2. del: Poimenovanja, definicije in parametri teksture površine (ISO 25178-2:2012)

Ta mednarodni standard določa minimalne zahteve za instrumente in sisteme iz razreda topografov roženice (CT). Določa tudi preskuse in postopke za preverjanje, ali je sistem ali instrument v skladu s tem mednarodnim standardom, pri čemer se zato lahko opredeli kot topograf roženice v skladu s tem mednarodnim standardom. Določa tudi preskuse in postopke, ki omogočajo preverjanje zmogljivosti sistemov, ki presegajo minimalne zahteve za topografe roženice. Ta mednarodni standard opredeljuje izraze, ki so specifični za ugotavljanje oblike roženice, da bodo standardizirani na celotnem področju očesne optike. Ta mednarodni standard se uporablja za instrumente, sisteme in metode za merjenje površinske oblike roženice človeškega očesa.

General Information

• Status: Withdrawn
• Public Enquiry End Date: 24-Mar-2008
• Publication Date: 04-Jul-2012
• Withdrawal Date: 31-Jan-2022
• ICS: 17.040.20 - Properties of surfaces
• ICS: 17.040.40 - Geometrical Product Specification (GPS)
• Technical Committee: ISEL - Mechanical elements
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 31-Jan-2022
• Due Date: 23-Feb-2022
• Completion Date: 01-Feb-2022
• Ref Project: EN ISO 25178-2:2012 - Geometrical product specifications (GPS) - Surface texture: Areal - Part 2: Terms, definitions and surface texture parameters (ISO 25178-2:2012)

Relations

• Replaced By: SIST EN ISO 25178-2:2022 - Geometrical product specifications (GPS) - Surface texture: Areal - Part 2: Terms, definitions and surface texture parameters (ISO 25178-2:2021)
• Effective Date: 26-Jan-2022

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 25178-2:2012
01-september-2012
6SHFLILNDFLMDJHRPHWULMVNLKYHOLþLQL]GHOND7HNVWXUDSRYUãLQHSORVNRYQDGHO
3RLPHQRYDQMDGHILQLFLMHLQSDUDPHWULWHNVWXUHSRYUãLQH,62
Geometrical product specifications (GPS) - Surface texture: Areal - Part 2: Terms,
definitions and surface texture parameters (ISO 25178-2:2012)
Geometrische Produktspezifikation (GPS) - Oberflächenbeschaffenheit: Flächenhaft -
Teil 2: Begriffe und Oberflächen-Kenngrößen (ISO 25178-2:2012)
Spécification géométrique des produits (GPS) - État de surface: surfacique - Partie 2:
Termes, définitions et paramètres d'états de surface (ISO 25178-2:2012)
Ta slovenski standard je istoveten z: EN ISO 25178-2:2012
ICS:
17.040.20 Lastnosti površin Properties of surfaces
SIST EN ISO 25178-2:2012 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 25178-2:2012

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SIST EN ISO 25178-2:2012


EUROPEAN STANDARD
EN ISO 25178-2

NORME EUROPÉENNE

EUROPÄISCHE NORM
April 2012
ICS 17.040.20
English Version
Geometrical product specifications (GPS) - Surface texture:
Areal - Part 2: Terms, definitions and surface texture parameters
(ISO 25178-2:2012)
Spécification géométrique des produits (GPS) - Etat de Geometrische Produktspezifikation (GPS) -
surface: Surfacique - Partie 2: Termes, définitions et Oberflächenbeschaffenheit: Flächenhaft - Teil 2: Begriffe
paramètres d'états de surface (ISO 25178-2:2012) und Oberflächen-Kenngrößen (ISO 25178-2:2012)
This European Standard was approved by CEN on 17 September 2011.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.





EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 25178-2:2012: E
worldwide for CEN national Members.

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SIST EN ISO 25178-2:2012
EN ISO 25178-2:2012 (E)
Contents Page
Foreword .3

2

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SIST EN ISO 25178-2:2012
EN ISO 25178-2:2012 (E)
Foreword
This document (EN ISO 25178-2:2012) has been prepared by Technical Committee ISO/TC 213 "Dimensional
and geometrical product specifications and verification" in collaboration with Technical Committee
CEN/TC 290 “Dimensional and geometrical product specification and verification” the secretariat of which is
held by AFNOR.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by October 2012, and conflicting national standards shall be withdrawn at
the latest by October 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 25178-2:2012 has been approved by CEN as a EN ISO 25178-2:2012 without any
modification.

3

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SIST EN ISO 25178-2:2012

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SIST EN ISO 25178-2:2012

INTERNATIONAL ISO
STANDARD 25178-2
First edition
2012-04-01

Geometrical product specifications
(GPS) — Surface texture: Areal —
Part 2:
Terms, definitions and surface texture
parameters
Spécification géométrique des produits (GPS) — État de surface:
Surfacique —
Partie 2: Termes, définitions et paramètres d'états de surface




Reference number
ISO 25178-2:2012(E)
©
ISO 2012

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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)

COPYRIGHT PROTECTED DOCUMENT


©  ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56  CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland

ii © ISO 2012 – All rights reserved

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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
Contents Page
Foreword . iv
Introduction . v
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 1
3.1  General terms . 1
3.2  Geometrical parameter terms . 4
3.3  Geometrical feature terms . 5
4  Field parameter definitions . 8
4.1  Height parameters . 8
4.2  Spatial parameters . 9
4.3  Hybrid parameters . 11
4.4  Functions and related parameters . 11
4.5  Miscellaneous parameters . 21
5  Determination of areal parameters for stratified functional surfaces of scale-limited
surfaces . 22
5.1  Calculating the parameters Sk, Smr1 and Smr2 . 22
5.2  Calculating the equivalent straight line . 22
5.3  Calculating the parameters Spk and Svk . 22
5.4  Calculating the parameters Spq, Svq and Smq . 22
6  Feature characterization . 24
6.1  General . 24
6.2  Type of texture feature . 25
6.3  Segmentation . 25
6.4  Determining significant features . 25
6.5  Section of feature attributes . 27
6.6  Attribute statistics . 28
6.7  Feature characterization convention . 28
6.8  Named feature parameters . 28
Annex A (informative) Segmentation . 31
Annex B (informative) Fractal methods . 36
Annex C (informative) Basis for areal surface texture standards . 41
Annex D (informative) Concept diagrams . 42
Annex E (informative) Relation to the GPS matrix model . 45
Bibliography . 46

© ISO 2012 – All rights reserved iii

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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(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 25178-2 was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product
specifications and verification.
ISO 25178 consists of the following parts, under the general title Geometrical product specifications (GPS) —
Surface texture: Areal:
 Part 2: Terms, definitions and surface texture parameters
 Part 3: Specification operators
 Part 6: Classification of methods for measuring surface texture
 Part 70: Physical measurement standards
 Part 71: Software measurement standards
 Part 601: Nominal characteristics of contact (stylus) instruments
 Part 602: Nominal characteristics of non-contact (confocal chromatic probe) instruments
 Part 604: Nominal characteristics of non-contact (coherence scanning interferometry) instruments
 Part 605: Nominal characteristics of non-contact (point autofocus probe) instruments
 Part 701: Calibration and measurement standards for contact (stylus) instruments
The following parts are under preparation:
 Part 1: Indication of surface texture
 Part 603: Nominal characteristics of non-contact (phase-shifting interferometric microscopy) instruments

iv © ISO 2012 – All rights reserved

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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
Introduction
This part of ISO 25178 is a geometrical product specification (GPS) standard and is to be regarded as a
general GPS standard (see ISO/TR 14638). It influences chain link 2 of the chains of standards on areal
surface texture.
The ISO/GPS Masterplan given in ISO/TR 14638 gives an overview of the ISO/GPS system of which this
document is a part. The fundamental rules of ISO/GPS given in ISO 8015 apply to this document and the
default decision rules given in ISO 14253-1 apply to specifications made in accordance with this document,
unless otherwise indicated.
For more detailed information of the relation of this standard to the GPS matrix model, see Annex E.
This part of ISO 25178 develops the terminology, concepts and parameters for areal surface texture.
© ISO 2012 – All rights reserved v

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SIST EN ISO 25178-2:2012

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SIST EN ISO 25178-2:2012
INTERNATIONAL STANDARD ISO 25178-2:2012(E)

Geometrical product specifications (GPS) — Surface texture:
Areal —
Part 2:
Terms, definitions and surface texture parameters
1 Scope
This part of ISO 25178 specifies terms, definitions and parameters for the determination of surface texture by
areal methods.
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/TS 16610-1:2006, Geometrical product specifications (GPS) — Filtration — Part 1: Overview and basic
concepts
ISO 17450-1:2011, Geometrical product specifications (GPS) — General concepts — Part 1: Model for
geometrical specification and verification
1)
ISO 25178-3:— , Geometrical product specifications (GPS) — Surface texture: Areal — Part 3: Specification
operators
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 17450-1 and ISO/TS 16610-1, and
the following apply.
3.1 General terms
3.1.1
non-ideal surface model
skin model
model of the physical interface of the workpiece with its environment
[ISO 17450-1:2011, 3.2.2]

1) To be published.
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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
3.1.1.1
mechanical surface
boundary of the erosion, by a spherical ball of radius r, of the locus of the centre of an ideal tactile sphere,
also with radius r, rolled over the skin model of a workpiece
[ISO 14406:2010, 3.1.1]
3.1.1.2
electromagnetic surface
surface obtained by the electromagnetic interaction with the skin model of a workpiece
[ISO 14406:2010, 3.1.2]
3.1.2
specification coordinate system
system of coordinates in which surface texture parameters are specified
NOTE If the nominal surface is a plane (or portion of a plane), it is common (practice) to use a rectangular coordinate
system in which the axes form a right-handed Cartesian set, the X-axis and the Y-axis also lying on the nominal surface,
and the Z-axis being in an outward direction (from the material to the surrounding medium). This convention is adopted
throughout the rest of this part of ISO 25178.
3.1.3
primary surface
surface portion obtained when a surface portion is represented as a specified primary mathematical model
with specified nesting index
[ISO/TS 16610-1:2006, 3.3]
NOTE In this part of ISO 25178, an S-filter is used to derive the primary surface.
3.1.3.1
primary extracted surface
finite set of data points sampled from the primary surface
[ISO 14406:2010, 3.7]
3.1.4
surface filter
filtration operator applied to a surface
NOTE In practice, the filter operator will apply to a primary extracted surface.
3.1.4.1
S-filter
surface filter which removes small scale lateral components from the surface resulting in the primary surface
3.1.4.2
L-filter
surface filter which removes large scale lateral components from the primary surface or S-F surface
3.1.4.3
F-operation
operation which removes form from the primary surface
NOTE 1 Some F-operations (such as association operations) have a very different action to that of filtration. Though
their action can limit the larger lateral scales of a surface this action is very fuzzy hence the fuzzy line for the action of the
F-operation in Figure 1.
NOTE 2 Many L-filters are sensitive to form and require an F-operation first as a prefilter before being applied.
2 © ISO 2012 – All rights reserved

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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
3.1.5
S-F surface
surface derived from the primary surface by removing the form using an F-operation
NOTE Figure 1 illustrates the relationship between the S-F surface and the S-filter and F-operation.
3.1.6
S-L surface
surface derived from the S-F surface by removing the large scale components using an L-filter
NOTE Figure 1 illustrates the relationship between the S-L surface and the S-filter and L-filter.
L
S F
a b
c
d
e
f

a
Small scale.
S F
S-F
b
Large scale.
c
Scale axis.
d
F-operation.
L
S
S-L
e
S-filter.

f
L-filter.
Figure 1 — Relationships between the S-filter, L-filter, F-operation and S-F and S-L surfaces
3.1.7
scale-limited surface
S-F surface or a S-L surface
3.1.8
reference surface
surface associated to the scale-limited surface according to a criterion
NOTE 1 The result is used as a reference surface for surface texture parameters.
NOTE 2 Examples of reference surfaces include plane, cylinder and sphere.
3.1.9
evaluation area
portion of the scale-limited surface for specifying the area under evaluation
NOTE See ISO 25178-3 for more information.
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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
3.1.10
definition area
portion of the evaluation area for defining the parameters characterizing the scale-limited surface
3.2 Geometrical parameter terms
3.2.1
field parameter
parameter defined from all the points on a scale-limited surface
NOTE Field parameters are defined in Clause 4.
3.2.2
feature parameter
parameter defined from a subset of predefined topographic features from the scale-limited surface
NOTE Feature parameters are defined in Clause 5.
3.2.3
V-parameter
material volume or void volume field or feature parameter
3.2.4
S-parameter
field or feature parameter that is not a V-parameter
3.2.5
height
signed normal distance from the reference surface to the scale-limited surface
NOTE 1 The distance is defined normal to the reference surface.
NOTE 2 The height is negative, if from the reference surface the point lies in the direction of the material.
3.2.6
ordinate value
z(x,y)
height of the scale-limited surface at position x,y
NOTE The coordinate system is based on the reference surface.
3.2.7
local gradient vector

zz
,

x y

gradient of the scale-limited surface at position x,y
NOTE For specific implementation, see ISO 25178-3.
3.2.8
autocorrelation function
f (t ,t )
ACF x y
function which describes the correlation between a surface and the same surface translated by (t ,t )
x y
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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
zx(),,y z(xt y t)dxdy
xy

A
ft ,t 

ACF xy
zx(),,y zx()ydxdy

A
with A being the definition area
3.2.9
Fourier transformation
F(p,q)
operator which transforms the scale-limited surface into Fourier space
()ipx iqy
F()pq,, z(xy)e dxdy

A
with A being the definition area
3.2.9.1
angular spectrum
f (s)
APS
power spectrum for a given direction, with respect to a specified direction  in the plane of the definition area
R
1
2
f (sr)Frsin()s,rcos()s dr

APS

R
2
where R to R is the range of integration in the radial direction and s the specified direction
1 2
NOTE 1 The positive x-axis is defined as the zero angle.
NOTE 2 The angle is positive in an anticlockwise direction from the x-axis.
3.3 Geometrical feature terms
3.3.1
peak
point on the surface which is higher than all other points within a neighbourhood of that point
NOTE 1 For discrete data, a triangulization of the surface is necessary.
NOTE 2 There is a theoretical possibility of a plateau. In practice, this can be avoided by the use of an infinitesimal tilt.
NOTE 3 For specific implementation, see ISO 25178-3.
3.3.1.1
hill
region around a peak such that all maximal upward paths end at the peak
3.3.1.2
course line
curve separating adjacent hills
3.3.2
pit
point on the surface which is lower than all other points within a neighbourhood of that point
NOTE 1 For discrete data, a triangulization of the surface is necessary.
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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
NOTE 2 There is a theoretical possibility of a plateau. In practice, this can be avoided by the use of an infinitesimal tilt.
NOTE 3 For specific implementation, see ISO 25178-3.
3.3.2.1
dale
region around a pit such that all maximal downward paths end at the pit
NOTE An areal motif is a dale; see ISO 12085.
3.3.2.2
ridge line
curve separating adjacent dales
3.3.3
saddle
set of points on the scale-limited surface where ridge lines and course lines cross
3.3.3.1
saddle point
saddle consisting of one point
3.3.4
topographic feature
areal, line or point feature on a scale-limited surface
3.3.4.1
areal feature
hill or dale
3.3.4.2
line feature
course line or ridge line
3.3.4.3
point feature
peak, pit or saddle point
3.3.5
contour line
line on the surface consisting of points of equal height
3.3.6
segmentation
method which partitions a scale-limited surface into distinct regions
3.3.6.1
segmentation function
function which splits a set of “events” into two distinct sets called the significant events and the insignificant
events and which satisfies the three segmentation properties
NOTE 1 Examples of events are: ordinate values, point features, etc.
NOTE 2 A full mathematical description of the segmentation function and the three segmentation properties can be
found in Scott (2004) (see Reference [16]).
NOTE 3 The mathematical treatment of the segmentation function and segmentation properties will be transferred to a
future ISO 16610 series document on segmentation.
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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
3.3.6.2
first segmentation property
P1
property where each event is allocated to the set of significant events or the set of insignificant events but not
both
P1:AE,()A ()AA(A) ()A
where
E is the set of all events;
 (.) maps events onto the set of significant events;
 (.) maps events onto the set of insignificant events
3.3.6.3
second segmentation property
P2
property where if a significant event is removed from the set of events then the remaining significant events
are contained in the new set of significant events
P2:A BE , ()A()B
where
E is the set of all events;
 (.) maps events onto the set of insignificant events
3.3.6.4
third segmentation property
P3
property where if an insignificant event is removed from the set of events then the same set of significant
events is obtained
P3:A BE ,()BA (A)()B
where
E is the set of all events;
 (.) maps events onto the set of significant events
3.3.7
change tree
graph where each contour line is plotted as a point against height in such a way that adjacent contour lines
are adjacent points on the graph
NOTE Peaks and pits are represented on a change tree by the end of lines. Saddle points are represented on a
change tree by joining lines. See Annex A for more details concerning change trees.
3.3.7.1
pruning
method to simplify a change tree in which lines from peaks (or pits) to their nearest connected saddle points
are removed
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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
3.3.7.2
local peak height
difference between the height of a peak and the height of the nearest connected saddle on the change tree
3.3.7.3
local pit height
difference between the height of the nearest connected saddle on the change tree and the height of a pit
3.3.7.4
Wolf pruning
pruning where lines are removed in order from the peak/pit with the smallest local peak/pit height up to the
peak/pit with a specified local peak/pit height
NOTE The local peak/pit heights will change during Wolf pruning as removing lines from a change tree will also
remove the associated saddle point.
3.3.8
Wolf peak height
minimum threshold at which a peak is pruned using Wolf pruning
3.3.9
Wolf pit height
minimum threshold at which a pit is pruned using Wolf pruning
3.3.10
peak height
height of the peak
3.3.11
pit height
height of the pit
3.3.12
height discrimination
minimum Wolf peak height or Wolf pit height of the scale-limited surface which should be taken into account
NOTE The height discrimination is usually specified as a percentage of Sz (4.1.6).
4 Field parameter definitions
In the terminological entries below, each term is followed by its parameter (abbreviated term), then its symbol.
Whereas abbreviated terms can contain multiple letters, symbols consist only of a single letter with subscripts
as needed. Symbols are used in the equations shown in this document. The reason for this differentiation is to
avoid misinterpretation of compound letters as an indication of multiplication between quantities in equations.
The parameters (abbreviated terms) are used in product documentation, drawings and data sheets.
4.1 Height parameters
All height parameters are defined over the definition area.
4.1.1
root mean square height of the scale-limited surface
Sq
S
q
root mean square value of the ordinate values within a definition area (A)
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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
1
2
Sz ()x,dyxdy
q

A
A
4.1.2
skewness of the scale-limited surface
Ssk
S
sk
quotient of the mean cube value of the ordinate values and the cube of Sq within a definition area (A)

11
3

Sz ()x,dyxdy
sk

3
A
S
q
A
4.1.3
kurtosis of the scale-limited surface
Sku
S
ku
quotient of the mean quartic value of the ordinate values and the fourth power of Sq within a definition area (A)


11
4

Sz ()x,dyxdy
ku

4
A

S
q
A
4.1.4
maximum peak height of the scale limited surface
Sp
S
p
largest peak height value within a definition area
4.1.5
maximum pit height of the scale limited surface
Sv
S
v
minus the smallest pit height value within a definition area
4.1.6
maximum height of the scale-limited surface
Sz
S
z
sum of the maximum peak height value and the maximum pit height value within a definition area
4.1.7
arithmetical mean height of the scale limited surface
Sa
S
a
arithmetic mean of the absolute of the ordinate values within a definition area (A)
1
Sz ()x,dyxdy
a
A
A
4.2 Spatial parameters
All spatial parameters are defined over the definition area.
© ISO 2012 – All rights reserved 9

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SIST EN ISO 25178-2:2012
ISO 25178-2:2012(E)
4.2.1
autocorrelati
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