SIST EN ISO 16610-85:2014

Geometrical product specifications (GPS) - Filtration- Part 85: Morphological areal filters: Segmentation (ISO 16610-85:2013)

This part of ISO 16610 develops the terminology and concepts for areal morphological segmentation. In particular it describes the watershed segmentation method and the Wolf pruning method. This document assumes a continuous surface.

Geometrische Produktspezifikation (GPS) - Filterung - Teil 85: Morphologische Flächenfilterung: Segmentierung (ISO 16610-85:2013)

Dieser Teil von ISO 16610 entwickelt die Terminologie und die Konzepte der flächenhaften morphologischen Zerlegung. Er beschreibt insbesondere die Wasserscheiden Zerlegungsmethode und die Wolf Beschnei-dungsmethode.

Spécification géométrique des produits (GPS) - Filtrage - Partie 85: Filtres surfaciques morphologiques: Segmentation (ISO 16610-85:2013)

L'ISO 16610-85:2013 développe la terminologie et les concepts applicables à la segmentation morphologique surfacique. Elle décrit en particulier la méthode de segmentation par ligne de partage des eaux et la méthode d'élagage de Wolf. Le présent document suppose une surface continue.

Specifikacija geometrijskih veličin izdelka (GPS) - Filtriranje - 85. del: Morfološki ploskovni filtri: Segmentacija (ISO 16610-85:2013)

Ta del standarda ISO 16610 razvija terminologijo in pojme za morfološko ploskovno segmentacijo. Predvsem opisuje metodo delitve površja na porečja in metodo določanja razmerij med posameznimi točkami (Wolfova metoda). Ta dokument predvideva neprekinjeno površino.

General Information

• Status: Published
• Publication Date: 26-May-2014
• ICS: 17.040.20 - Properties of surfaces
• ICS: 17.040.40 - Geometrical Product Specification (GPS)
• Technical Committee: ISEL - Mechanical elements
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 13-May-2014
• Due Date: 18-Jul-2014
• Completion Date: 27-May-2014
• Ref Project: EN ISO 16610-85:2013 - Geometrical product specifications (GPS) - Filtration- Part 85: Morphological areal filters: Segmentation (ISO 16610-85:2013)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 16610-85:2014
01-julij-2014
6SHFLILNDFLMDJHRPHWULMVNLKYHOLþLQL]GHOND*36)LOWULUDQMHGHO0RUIRORãNL
SORVNRYQLILOWUL6HJPHQWDFLMD,62
Geometrical product specifications (GPS) - Filtration- Part 85: Morphological areal filters:
Segmentation (ISO 16610-85:2013)
Geometrische Produktspezifikation (GPS) - Filterung - Teil 85: Morphologische
Flächenfilterung: Segmentierung (ISO 16610-85:2013)
Spécification géométrique des produits (GPS) - Filtrage - Partie 85: Filtres surfaciques
morphologiques: Segmentation (ISO 16610-85:2013)
Ta slovenski standard je istoveten z: EN ISO 16610-85:2013
ICS:
17.040.20 Lastnosti površin Properties of surfaces
SIST EN ISO 16610-85:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 16610-85:2014

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SIST EN ISO 16610-85:2014


EUROPEAN STANDARD
EN ISO 16610-85

NORME EUROPÉENNE

EUROPÄISCHE NORM
February 2013
ICS 17.040.20
English Version
Geometrical product specifications (GPS) - Filtration- Part 85:
Morphological areal filters: Segmentation (ISO 16610-85:2013)
Spécification géométrique des produits (GPS) - Filtrage - Geometrische Produktspezifikation (GPS) - Filterung - Teil
Partie 85: Filtres surfaciques morphologiques: 85: Morphologische Flächenfilterung: Segmentierung (ISO
Segmentation (ISO 16610-85:2013) 16610-85:2013)
This European Standard was approved by CEN on 30 July 2012.

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, Former Yugoslav Republic of Macedonia, 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
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16610-85:2013: E
worldwide for CEN national Members.

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SIST EN ISO 16610-85:2014
EN ISO 16610-85:2013 (E)
Contents Page
Foreword . 3

2

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SIST EN ISO 16610-85:2014
EN ISO 16610-85:2013 (E)
Foreword
This document (EN ISO 16610-85:2013) 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 August 2013, and conflicting national standards shall be withdrawn at
the latest by August 2013.
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, Former Yugoslav Republic of Macedonia, 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 16610-85:2013 has been approved by CEN as EN ISO 16610-85:2013 without any
modification.

3

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SIST EN ISO 16610-85:2014

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SIST EN ISO 16610-85:2014
INTERNATIONAL ISO
STANDARD 16610-85
First edition
2013-02-01
Geometrical product specifications
(GPS) — Filtration —
Part 85:
Morphological areal filters:
Segmentation
Spécification géométrique des produits (GPS) — Filtrage —
Partie 85: Filtres surfaciques morphologiques: Segmentation
Reference number
ISO 16610-85:2013(E)
©
ISO 2013

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SIST EN ISO 16610-85:2014
ISO 16610-85:2013(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2013
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
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 2013 – All rights reserved

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Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Geometrical feature terms . 1
3.2 Segmentation . 3
3.3 Pruning . 5
4 Segmentation details . 7
4.1 General . 7
4.2 Basic segmentation . 7
4.3 Watershed segmentation .10
4.4 Watershed segmentation using Wolf pruning .12
5 General information .14
Annex A (informative) Additional information about segmentation .15
Annex B (informative) Wolf pruning examples .16
Annex C (informative) Relationship to the filtration matrix model .21
Annex D (informative) Concept diagrams .22
Annex E (informative) Relation to the GPS matrix model.24
Bibliography .26
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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 16610-85 was prepared by Technical Committee ISO/TC 213, Dimensional and geometrical product
specifications and verification.
This first edition of ISO 16610-85 replaces Annex A (Segmentation) in ISO 25178-2:2012.
ISO 16610 consists of the following parts, under the general title Geometrical product specifications
(GPS) — Filtration:
— Part 1: Overview and basic concepts [Technical Specification]
— Part 20: Linear profile filters: Basic concepts
— Part 21: Linear profile filters: Gaussian filters
— Part 22: Linear profile filters: Spline filters
— Part 28: Profile filters: End effects [Technical Specification]
— Part 29: Linear profile filters: Spline wavelets
— Part 30: Robust profile filters: Basic concepts [Technical Specification]
— Part 31: Robust profile filters: Gaussian regression filters [Technical Specification]
— Part 32: Robust profile filters: Spline filters [Technical Specification]
— Part 40: Morphological profile filters: Basic concepts
— Part 41: Morphological profile filters: Disk and horizontal line-segment filters
— Part 49: Morphological profile filters: Scale space techniques
— Part 60: Linear areal filters: Basic concepts
— Part 61: Linear areal filters: Gaussian filters
— Part 71: Robust areal filters: Gaussian regression filters
— Part 85: Morphological areal filters: Segmentation
The following parts are planned:
— Part 62: Linear areal filters: Spline filters
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— Part 69: Linear areal filters: Spline wavelets
— Part 70: Robust areal filters: Basic concepts
— Part 72: Robust areal filters: Spline filters
— Part 80: Morphological areal filters: Basic concepts
— Part 81: Morphological areal filters: Sphere and horizontal planar segment filters
— Part 82: Morphological areal filters: Motif filters
— Part 89: Morphological areal filters: Scale space techniques
See Annex C for relationships to other filtration documents.
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Introduction
This part of ISO 16610 is a geometrical product specification (GPS) standard and is to be regarded as
a general GPS standard (see ISO 14638). It influences the feature characteristics chain link in the GPS
matrix structure.
The ISO/GPS Masterplan given in ISO 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 on the relation of this part of ISO 16610 to other standards and to the GPS
matrix model, see Annex E.
This part of ISO 16610 develops the terminology and concepts for areal segmentation.
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SIST EN ISO 16610-85:2014
INTERNATIONAL STANDARD ISO 16610-85:2013(E)
Geometrical product specifications (GPS) — Filtration —
Part 85:
Morphological areal filters: Segmentation
1 Scope
This part of ISO 16610 develops the terminology and concepts for areal morphological segmentation.
In particular, it describes the watershed segmentation method and the Wolf pruning method. This
document assumes a continuous surface.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
1)
ISO 16610-1 , Geometrical Product Specifications (GPS) — Data extraction techniques by sampling and
filtration — Part 1: Basic terminology
ISO 25178-2:2012, Geometrical product specifications (GPS) — Surface texture: Areal — Part 2: Terms,
definitions and surface texture parameters
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 16610-1, ISO 25178-2:2012 and
the following apply.
3.1 Geometrical feature terms
3.1.1
peak
point on the surface which is higher than all other points within a neighbourhood of that point
Note 1 to entry: For discrete data, a triangulization of the surface is necessary.
Note 2 to entry: There is a theoretical possibility of a plateau. In practice, this can be avoided by the use of an
infinitesimal tilt.
Note 3 to entry: For specific implementation, see ISO 25178-3.
[SOURCE: ISO 25178-2:2012, 3.3.1]
3.1.1.1
Maxwellian hill
region around a peak such that all maximum upward paths end at the peak
Note 1 to entry: In ISO 25178-2:2012, 3.3.1.1, the term corresponding to this definition was “hill”.
1)  To be published (Revision of ISO/TS 16610-1:2006).
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3.1.1.2
course line
curve separating adjacent hills
[SOURCE: ISO 25178-2:2012, 3.3.1.2]
3.1.1.3
hill
region around a single dominant peak whose boundary consists of a ring of course lines
Note 1 to entry: There may be other peaks in the hill but they will all be insignificant compared to the dominant peak.
3.1.2
pit
point on the surface which is lower than all other points within a neighbourhood of that point
Note 1 to entry: For discrete data, a triangulization of the surface is necessary.
Note 2 to entry: There is a theoretical possibility of a plateau. In practice, this can be avoided by the use of an
infinitesimal tilt.
Note 3 to entry: For specific implementation, see ISO 25178-3.
[SOURCE: ISO 25178-2:2012, 3.3.2]
3.1.2.1
Maxwellian dale
region around a pit such that all maximum downward paths end at the pit
Note 1 to entry: In ISO 25178-2:2012, 3.3.1.1, the term corresponding to this definition was “dale”.
3.1.2.2
ridge line
curve separating adjacent dales
[SOURCE: ISO 25178-2:2012, 3.3.2.2]
3.1.2.3
dale
region around a single dominant pit whose boundary consists of a ring of ridge lines
Note 1 to entry: There may be other pits in the dale but they will all be insignificant compared to the dominant pit.
Note 2 to entry: Motifs are dales, see ISO 12085:1996.
3.1.3
saddle
set of points on the surface where ridge lines and course lines cross
[SOURCE: ISO 25178-2:2012, 3.3.3, modified — ISO 25178-2:2012 had “scale-limited ridge lines” in
the definition.]
3.1.3.1
saddle point
saddle consisting of one point
[SOURCE: ISO 25178-2:2012, 3.3.3.1]
3.1.4
topographic feature
areal, line or point feature on a surface
[SOURCE: ISO 25178-2:2012, 3.3.4, modified — ISO 25178-2:2012 had “scale-limited surface” in the definition.]
2 © ISO 2013 – All rights reserved

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3.1.4.1
areal feature
hill or dale
[SOURCE: ISO 25178-2:2012, 3.3.4.1]
3.1.4.2
line feature
course line or ridge line
[SOURCE: ISO 25178-2:2012, 3.3.4.2]
3.1.4.3
point feature
peak, pit or saddle point
[SOURCE: ISO 25178-2:2012, 3.3.4.3]
3.1.5
contour line
line on the surface consisting of points of equal height
[SOURCE: ISO 25178-2:2012, 3.3.5]
3.2 Segmentation
3.2.1
segmentation
method which partitions a surface into distinct regions
[SOURCE: ISO 25178-2:2012, 3.3.6, modified — ISO 25178-2:2012 had “scale-limited surface” in the definition.]
3.2.1.1
event
mutually exclusive surface portions whose union covers the whole surface
EXAMPLE Ordinate values, Maxwellian hills, Maxwellian dales, etc.
3.2.1.2
watershed segmentation
segmentation which uses the concept of filling dales (hills) with water to determine the saddle at which
the water first overflows and the adjacent dale (hill) into which it overflows
3.2.2
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 to entry: A full mathematical description of the segmentation function and the three segmentation
[8]
properties can be found in Scott (2004).
[SOURCE: ISO 25178-2:2012, 3.3.6.1, modified — Notes 1 and 3 have not been included here.]
3.2.3
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
Pa1: ∀⊆AE,(ΨΦAA)(∪=)(AAndΨΦ)(∩=A) ∅
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where
E is the set of all events;
Ψ (.)
maps events onto the set of significant events;
Φ(.)
maps events onto the set of insignificant events.
SEE: Figure 1.
E
A
Ψ (A) Φ (A)
Figure 1 — Venn diagram of first segmentation property
[SOURCE: ISO 25178-2:2012, 3.3.6.2]
3.2.4
second segmentation property
P2
property where 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:,∀⊆AB⊆⊆EAΦΦ() ()B
where
E is the set of all events;
Ψ (.)
maps events onto the set of significant events;
Φ(.)
maps events onto the set of insignificant events.
SEE: Figure 2.
E
B
A
Ψ (B)
Ψ (A)
Φ (B)
Φ (A)
Figure 2 — Venn diagram of second segmentation property
[SOURCE: ISO 25178-2:2012, 3.3.6.3]
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3.2.5
third segmentation property
P3
property where an insignificant event is removed from the set of events then the same set of significant
events is obtained
P3:,∀⊆AB⊆⊆EBΨΨ() AA⇒=() Ψ ()B
where
E is the set of all events;
Ψ (.)
maps events onto the set of significant events;
Φ(.)
maps events onto the set of insignificant events.
SEE: Figure 3.
E
B
A
Ψ (A) = Ψ (B)
Φ (A)
Figure 3 — Venn diagram of third segmentation property
[SOURCE: ISO 25178-2:2012, 3.3.6.4]
3.3 Pruning
3.3.1
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 1 to entry: Peaks and pits are represented on a change tree by the end of lines. Saddle points are represented
on a change tree by lines joining. See Clause 4 for more details concerning change trees.
[SOURCE: ISO 25178-2:2012, 3.3.7, modified — The reference in the note has been changed to Clause 4.]
3.3.2
pruning
method to simplify a change tree in which lines from peaks (or pits) to their nearest connected saddle
points are removed
[SOURCE: ISO 25178-2:2012, 3.3.7.1]
3.3.3
height
signed normal distance from the reference surface to the surface
Note 1 to entry: The distance is defined normal to the reference surface.
Note 2 to entry: The height is negative, if from the reference surface, the point lies in the direction of the material.
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3.3.4
saddle height
height of the saddle
3.3.5
peak height
height of the peak
[SOURCE: ISO 25178-2:2012, 3.3.10]
3.3.5.1
local peak height
difference between the height of a peak and the height of the nearest connected saddle on the change tree
[SOURCE: ISO 25178-2:2012, 3.3.7.2]
3.3.6
pit height
height of the pit
[SOURCE: ISO 25178-2:2012, 3.3.11]
3.3.6.1
local pit height
difference between the height of a pit and the height of the nearest connected saddle on the change tree
[SOURCE: ISO 25178-2:2012, 3.3.7.3]
3.3.7
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 1 to entry: The local peak/pit heights will change during Wolf pruning as removing lines from a change tree
will also remove the associated saddle point.
Note 2 to entry: Other criteria for pruning are not covered in this part of ISO 16610. See References [9] and [10]
for examples.
[SOURCE: ISO 25178-2:2012, 3.3.7.4, modified — Note 2 to entry has been added.]
3.3.7.1
Wolf peak height
minimum height threshold at which a peak is pruned using Wolf pruning
[SOURCE: ISO 25178-2:2012, 3.3.8, modified — The word “height” has been added in the definition.]
3.3.7.2
Wolf pit height
minimum height threshold at which a pit is pruned using Wolf pruning
[SOURCE: ISO 25178-2:2012, 3.3.9, modified — The word “height” has been added in the definition.]
3.3.8
height discrimination
minimum Wolf peak height or Wolf pit height of the surface which should be taken into account
Note 1 to entry: Height discrimination is a nesting index for Wolf pruning segmentation.
[SOURCE: ISO 25178-2:2012, 3.3.12, modified — ISO 25178-2:2012 had “scale-limited surface” in the
definition. Note 1 to entry is different.]
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3.3.9
virtual pit
imaginary pit, that has a minus infinity pit height, to which all edge points are connected
3.3.10
virtual pit condition
condition where a virtual pit is assumed
4 Segmentation details
4.1 General
A watershed segmentation method claiming to comply with this document shall conform to 4.2 to 4.3
and a Wolf pruning method claiming to comply with this document shall conform to 4.2 to 4.4.
4.2 Basic segmentation
4.2.1 General
Segmentation is a filtration operation (as defined in ISO 16610-1) that spatially decomposes a surface
into mutually exclusive portions of that surface (see Figure 1). Segmentation filtration requires: the
objects being filtered i.e. the segments; the rule for segment combination e.g. the watershed rule; and the
rule which states which segments are significant e.g. Wolf pruning. Associated with each segmentation
method is a nesting index such that large values of the nesting index correspond to large surface portions
and smaller values of the nesting index correspond to smaller surface portions (compare Figures 4 and 5).
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Dimensions in millimetres
Figure 4 — Example of segmentation of a surface from a grinding wheel with Wolf pruning
5 % total height
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Dimensions in millimetres
Figure 5 — Example of segmentation of a surface from a grinding wheel with Wolf pruning
15 % total height
In more detail, a surface consists of a set of “events” (3.2.1.1) for example:
— a set of all the extracted points from the surface;
— a set of all the Maxwellian hills;
— a set of all the Maxwellian dales, etc.
Segmentation then consists of:
a) determining which events are significant, at a particular nesting index, through the use of a
segmentation function; and
b) determining to which significant event each insignificant event should be combined.
Each surface portion, of the segmentation, then consists of a significant event together with all the
insignificant events that have been combined with it.
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4.2.2 Rules for stable segmentation
A segmentation function consists of splitting the set of “events” into two distinct sets called the
significant events and the insignificant events. For the segmentation function to give unique and stable
results the segmentation function shall satisfy the following three segmentation properties:
P1: Each event is allocated to one and only one of these two sets (i.e. the set of sig-
nificant events and the set of insignificant events).
P2: If a significant event is removed from the set of events, then the remaining sig-
nificant events are contained in the new set of significant events.
P3: If an insignificant event is removed from the set of events, then the same set of
significant events is obtained.
It can be shown that all segmentation functions that satisfy these three properties can be mapped
[13]
one-to-one onto a certain subset of algebraic morphological closing filters. Algebraic morphological
closing filters are widely used in image analysis. They are set functions with the following three defining
[14]
properties:
a) all sets are subsets of their own closings;
b) a closing of a closing of a set is the closing of the original set;
c) a closing of a subset is a subset of the closing of the original set.
The particular subsets of the closing filters that the segmentation functions map onto are the closings
with the following properties:
If two sets of events give the same closing, then their intersection also gives the same closing
For any closing that satisfies this property, we can map it one-to-one onto a particular segmentation
function as follows:
For any set of events, consider the smallest subset of this set that gives the same closing as the original
set of events. It can be shown that this particular subset is unique and well defined and corresponds to
the set of significant events and its complement, with respect to the set of events, corresponds to the set
of insignificant events. The inverse mapping is also well defined.
4.3 Watershed segmentation
4.3.1 General
The watershed method consists of gradually filling insignificant dales with water. The water will
eventually flow out of each dale, at a saddle point, into an adjacent dale. If that dale is significant combine
the two dales. Otherwise continue to fill the new lake until the water flows into a significant dale; All the
filled insignificant dales are then combined with the significant dale. By inverting the landscape so hills
become dales, etc., a similar process will establish the combination of insignificant hills to significant hills.
For this part of ISO 16610, the set of events shall consist of areal features and the combination rule shall
consist of the watershed method. Segmentation that uses the watershed method as the combination rule
is called watershed se
...