6 Spatial Data and XML

(1)

6.1 Standards 6.2 XML

6.3 GML 6.4 XSLT

6 Spatial Data and XML

6.4 XSLT 6.5 SVG

6.6 Summary

(2)

• Collection of spatial data is particularly expensive

• Spatial data is durable, must be updated nevertheless

• Geoservices are increasingly offered by the internet

• Spatial data should be capable of being

6 Spatial Data and XML

• Spatial data should be capable of being integrated and easily interchangeable

• Unified visualization of spatial data is desirable

• Preferably do not use individual formats but common standards

http://picture.yatego.com/

(3)

• De facto standards emerge over time through frequent use

• De facto standards are standardized by institutions

• In the area of standards for spatial data the following institutions are important

6.1 Standards

institutions are important

– International Organization for Standardization (ISO) – Open Geospatial Consortium (OGC)

– Working Committee of the Surveying Authorities of the States of the Federal Republic of Germany

(Arbeitsgemeinschaft der Vermessungsverwaltungen der Länder der Bundesrepublik Deutschland (AdV))

(4)

• International Organization for Standardization (ISO)

– International association of

standardization bodies from approx. 150 countries – Develops international standards in many technical

6.1 Standards

– Develops international standards in many technical areas

– Serves the exchange of goods and services and the mutual cooperation

– In the area of spatial information 5 working groups (in ISO/TC 211)

(5)

• National standardization bodies and ISO

6.1 Standards

http://www.geoinformation.net/

(6)

• ISO/TC 211 geographic information/geomatics

– Approx. 60 members

– Edits the standard series ISO 19100

6.1 Standards

(7)

• ISO 19107 Spatial Schema

6.1 Standards

(8)

• Geometry classes in the spatial schema

6.1 Standards

(9)

• Open Geospatial Consortium (OGC)

– International consortium of approx. 350 members (industry, administration, research)

– Develops fundamentals for standardized access methods for spatial information

6.1 Standards

(10)

– Products of the OGC are specifications

• Basic models, abstract specifications, implementation specifications

– Overview of abstract specifications

6.1 Standards

(11)

– Particularly important: Simple Features

• Standard for modeling the geometry of spatial objects

• 0-, 1-, 2-dimensional, straight lines, no topology

6.1 Standards

(12)

• SQL/MM spatial vs.

Simple Features geometry

6.1 Standards

(13)

• Cooperation between ISO/TC 211 and OGC

6.1 Standards

(14)

• Example: OpenGIS Catalog Service Implementation Specification

• Supports publishing and searching of geospatial metadata

6.1 Standards

metadata

– Approx. 200 printed pages – Includes syntax

of the catalog query language

http://www.opengeospatial.org/standards/cat

(15)

• Working Committee of the Surveying Authorities of the States of the Federal Republic

of Germany (Arbeitsgemeinschaft der

Vermessungsverwaltungen der Länder der Bundesrepublik Deutschland (AdV))

6.1 Standards

Bundesrepublik Deutschland (AdV))

– Coordination of the German cadastral surveying – Development of recommendations for

• Authoritative topographic cartographic information system

(amtliches topographisch-kartographisches Informationssystem (ATKIS))

• Authoritative real estate cadastre information system (amtliches Liegenschafts-Kataster-Informationssystem (ALKIS))

(16)

– Representation of the official German surveying in international institutions (see section 2.5 AAA-

Project)

– Provide ISO/OGC-compliant components for spatial data infrastructure

6.1 Standards

data infrastructure

– Example: AFIS-ALKIS-ATKIS specialized technical schema with 226 object types, including

• Buildings, including

• Groups of object types: information concerning buildings, including

(17)

• Object class: AX_Gebaeude with definition:

• A permanent building, whose documentation is required because of its importance as a property and which serves the purpose of the basic information of real estate cadastre

• With 20 attributes, including:

6.1 Standards

• Function of building with approx. 200 values, including:

• 2000 (business/industry), 2056 (pharmacy), 2081 (restaurant), 3071 (police)

– Provide the technical schemas (and all object copies) in ISO/OGC-compliant formats

(18)

• Example: a single building

<AX_Gebaeude gml:id="DEHHSERV00001FN1">

...

<gml:Polygon>

<gml:exterior>

<gml:Ring>

...

<gml:pos>3567807.047 5930017.550</gml:pos>

<gml:pos>3567810.850 5930024.755</gml:pos>

...

6.1 Standards

<gml:pos>3567810.850 5930024.755</gml:pos>

...

<gml:pos>3567807.047 5930017.550</gml:pos>

...

</gml:Ring>

</gml:exterior>

</gml:Polygon>

</position>

</AX_Gebaeude>

(19)

• Extensible Markup Language

• Representation of hierarchically structured data in the format of text files

6.2 XML

of text files

• Metalanguage for the description

and generation of markup languages

• "Special context-free grammar for defining specific context-free grammars"

• "Standard for exchanging data on the web"

(20)

• Markup language: language (words over an alphabet) with special symbols (tags) in the character strings

• HTML example:

6.2 XML

• HTML example:

[EE04]

<ul>

<li>

<p>Geotopographische Basisinformationen in digitaler Form

</li>

<li>

<p> Geodä tische Referenznetze

</li>

</ul>

(21)

• A (concrete) class of XML-based applications is also called document class

• An extension of such a class is called a document (or an application)

• The structure of

6.2 XML

• The structure of document classes can be specified by means of a

document type definition (DTD)

(22)

• Main components of the DTDs are

– Elements – Attributes – Entities

• Elements are the basic modules of XML

6.2 XML

• Elements are the basic modules of XML documents

– Consist of a start and an end tag – May be empty

– May be nested (hierarchical structure of XML documents)

(23)

• Example: a DTD of a city

6.2 XML

<!ELEMENT city(name, inhabitants?, area)>

<!ELEMENT name (#PCDATA)>

<!ELEMENT inhabitants(#PCDATA)>

<!ELEMENT area(polygon+)>

<!ELEMENT polygon (point, point, point, point, point*)>

<!ELEMENT point(x, y)>

<!ELEMENT x (#PCDATA)>

<!ELEMENT y (#PCDATA)>

(24)

– A well-formed instance:

6.2 XML

<?xml version="1.0" standalone="yes"?>

<!DOCTYPE city SYSTEM "city.dtd">

<city><name>Braunschweig</name>

<area>

...

</polygon>

</area>

</city>

(25)

– Another well-formed instance:

6.2 XML

<?xml version="1.0" standalone="yes"?>

<!DOCTYPE city SYSTEM "city.dtd">

<city><name>Ausschnitt</name>

<area>

<point><x>welchem</x><y>Text</y></point>

<point><x>Du</x><y>gleichst</y></point>

<point><x>dem</x><y>Geist</y></point>

...

<point><x>nicht</x><y>mir</y></point>

</polygon>

</area>

</city>

(26)

• Attributes specify additional properties of elements

6.2 XML

– Example: ^[EE04]

<text font-family= "Arial" font-weight= "bold" font-size= "350"

stroke= "#FFFFFF" fill= "#FFFFFF" x= "-130.0" y="115.0"> U

</text>

(27)

• Entities

– Placeholder for content

– Will be declared once and can be used repeatedly

– At each place of use the parser replaces reference by

6.2 XML

At each place of use the parser replaces reference by appropriate value

– Example:

<!ENTITY baumgrün "#00ff00">

<!ENTITY grenzviolett "#9900ff">

<path id="SN4100_einzelsignaturNadelholz"

d="M 130 0 L -50 0 0 -180 50 0"

fill="none" stroke-miterlimit="20"

stroke-linejoin="miter"

stroke-width="12" stroke="&baumgrün;"/>

(28)

• A central XML concept is integration of data and meta-data (XML documents include complete

self-descriptions)

• Therefore, removal of DTDs is obvious (for

6.2 XML

• Therefore, removal of DTDs is obvious (for reuse)

• Large-scale projects may have several DTDs (possible name conflicts)

(29)

• For combining XML documents multiple concepts exist

– Namespaces – XPath

6.2 XML

– XPointer – XLink

http://www.jeckle.de/

(30)

• Namespaces

– Are declared as attribute (of an element) and apply to all sub-trees of that element

– Include a Uniform Resource Identifier (URI) as address

6.2 XML

address

[EE04]

<AX_Bestandsdatenauszug

xmlns:gml="http://www.opengis.net/gml"...>

...<gml:featureMember>...

...</gml:featureMember>...

</AX_Bestandsdatenauszug>

(31)

• XML Path Language (XPath)

– Addressing within XML documents

– Basis of XSL Transformations (XSLT) and XPointer

– Navigation in XML documents (trees) with address paths

6.2 XML

• Address paths

– Absolute (begin with '/' for root node) or – Relative (to the current context node)

– Contain axis information, node tests, predicates

[EE04]

(32)

• XML Pointer Language (XPointer)

– Addressing parts of XML documents – Extension of XPath

– Simple references refer to XML elements which are identified by an ID

6.2 XML

identified by an ID

– Complex references with specifications of blocks (start-point, end-point, range)

</g>

<use transform="translate(120515.9,152201.3) rotate(136)"

xlink:href="#SN3316SymbolKirche"/>

(33)

• XML Linking Language (XLink)

– Syntax for defining links within XML documents

– XLinks are linking XML elements with other XML elements

– Declaration by xlink:href="URI"

6.2 XML

– Declaration by xlink:href="URI"

– URI information may contain XPointer expressions

– There are simple (xlink: type = "simple") and extended (xlink: type = "extended") XLinks

– Extended XLinks are linking more than two sources

(34)

• Structure of XML documents can be defined by DTDs

• However, expressiveness of DTDs is restricted

– No specific data <!ELEMENT city(name, inhabitants?, area)>

6.2 XML

– No specific data

types (only CDATA) – Only few structuring

options by sub-elements

– Integrity constraints hardly definable

<!ELEMENT city(name, inhabitants?, area)>

<!ELEMENT name (#PCDATA)>

<!ELEMENT inhabitants(#PCDATA)>

<!ELEMENT area(polygon+)>

<!ELEMENT polygon

(point, point, point, point, point*)>

<!ELEMENT point(x, y)>

<!ELEMENT x (#PCDATA)>

<!ELEMENT y (#PCDATA)>

(35)

• XML-Schema

– Language for modeling structured information – Describes by schema language

• Data types

6.2 XML-Schema

• Documents

• Document Groups

– Alternative to DTDs

– Element contents can be typed and reused

– Allows limitations of value ranges and specifications of cardinalities

</restriction>

</simpleType>

(36)

• Numerous data types are provided, including

– xsd:string, xsd:boolean, xsd:decimal, xsd:float, xsd:time, xsd:date, xsd:integer (xsd: namespace of XML-Schema)

• Construction of data types with

6.2 XML-Schema

– Base type with restrictions

• Length specifications, patterns, ranges, enumerations

• List types and

union types

<xsd:simpleType name="ObjektartName">

<xsd:restriction base="xsd:string">

<xsd:pattern value="A[XP]_[a-zA-Z0-9_]+"/>

</xsd:restriction>

</xsd:simpleType>

(37)

• Complex element declarations are possible

6.2 XML-Schema

(38)

• Example of a complex element declaration

6.2 XML-Schema

</choice>

</complexType>

</element>

</sequence>

</complexType>

</element>

</choice>

</complexType>

</element>

</sequence>

</complexType>

</element>

(39)

• Example of an element instance

6.2 XML-Schema

...

<Bezeichnung>Schriftformat F K 28 blau</Bezeichnung>

<Schriftart>Arial</Schriftart>

<Schriftstil>Fett, Kursiv</Schriftstil>

</Schriftfarbe>

</SchriftStyle>

<Effekt>Grossbuchstaben</Effekt>

</SchriftSignatur>

</Signatur>

...

</Signaturen>

(40)

• Definition of keys and foreign keys

6.2 XML-Schema

[EE04]

(41)

• Geography Markup Language

• Markup Language generated by the use of XML (and XML-Schema); XML application

• To exchange spatial objects (in the OGC context:

"features")

6.3 GML

"features")

• Defined by the Open Geospatial Consortium with the ISO TC 211

• Defines numerous constructs for modelling own spatial applications, including

– Objects (features) and geometries

(42)

• The current GML specification of the OGC (version 3.0)

consists of approx.

550 pages

6.3 GML

550 pages

(43)

• The basic elements and data types are defined in 33 XML-Schema documents (base schemas)

• A concrete application has to be derived from the given schemas

6.3 GML

(44)

• The central class is the abstract feature type

• “All specific feature types defined in application

schemas must be derived from AbstractFeatureType”

6.3 GML

</sequence>

</extension>

</complexContent>

</complexType>

(45)

• Among others the geometries of the “Simple Features” are provided

– Typically 2-dimensional geometries with straight lines – Including points, lines, polygons

6.3 GML

(46)

• Definition of the polygon type

6.3 GML

</complexType>

</element>

</complexType>

</element>

</sequence>

</extension>

</complexContent>

</complexType>

(47)

• Definition of an own feature type

6.3 GML

</sequence>

</extension>

</complexContent>

</complexType>

(48)

• AFIS ALKIS ATKIS schema of the AdV is a (very large) example of a GML-

compliant modeling of a spatial application

• Consists of a base schema (contains common base classes for spatial objects)

6.3 GML

http://www.adv-online.de/

base classes for spatial objects)

• And of technical schemas (containing all object classes needed for representing the information occurring in cadastral surveying)

• For ALKIS there exist more than 220 object types including numerous types of relationships

(49)

• Here only a very small example is presented:

the schema of a single object class

"AX_Gebaeude" (simplified)

6.3 GML

<element name="gebaeudefunktion"

type="adv:AX_GebaeudefunktionType"/>

<element maxOccurs="unbounded" minOccurs="0"

name="weitereGebaeudefunktion"

type="adv:AX_Weitere_GebaeudefunktionType"/>

name="name" type="string"/>

<element maxOccurs="unbounded" minOccurs="0" name="nutzung"

(50)

6.3 GML

<element minOccurs="0" name="bauweise"

type="adv:AX_Bauweise_GebaeudeType"/>

<element minOccurs="0" name="anzahlDerOberirdischenGeschosse"

type="integer"/>

<element minOccurs="0" name="anzahlDerUnterirdischenGeschosse"

type="integer"/>

<element minOccurs="0" name="dachform"

type="adv:AX_DachformType"/>

<element minOccurs="0" name="zustand"

type="adv: AX_Zustand_GebaeudeType"/>

name="baujahr" type="integer"/>

<element minOccurs="0" name="lageZurErdoberflaeche"

type="adv:AX_LageZurErdoberflaeche_GebaeudeType"/>

(51)

<element minOccurs="0" name="dachgeschossausbau"

type="adv:AX_Dachgeschossausbau_GebaeudeType"/>

name="zeigtAuf" type="gml:ReferenceType">

</element>

6.3 GML

name="gehoert" type="gml:ReferenceType">

</element>

</element>

name="haengtZusammenMit" type="gml:ReferenceType">

</element>

</sequence>

</extension>

</complexContent>

</complexType>

(52)

<AX_Gebaeude gml:id="DEHHSERV00001FN1">

...

<gml:Polygon>

<gml:exterior>

<gml:Ring>

<gml:pos>3567807.047 5930017.550</gml:pos>

– An instance of "AX_Gebaeude" (simplified)

6.3 GML

"position":

inherited

<gml:pos>3567807.047 5930017.550</gml:pos>

<gml:pos>3567810.850 5930024.755</gml:pos>

...

<gml:pos>3567807.047 5930017.550</gml:pos>

</gml:Ring>

</gml:exterior>

</gml:Polygon>

</position>

</AX_Gebaeude>

inherited of class

AG_ObjektType

(53)

• GML serves (also) for the exchange of spatial objects

• Therefor the Web Feature Service (WFS) was defined

6.3 GML

defined

– Web-based access to data "of a distributed GIS"

– Only vector data are exchanged

– Requests are sent as a HTTP request from a client to the WFS

(54)

– WFS offers the following operations

• GetCapabilities

• GetFeature

• DescribeFeatureType

• Transaction

6.3 GML

• LockFeature

• GetCapabilities

– Describes which WFS services are available – Gives the names of the

available feature types

(55)

• DescribeFeatureType

– Describes the schema of a feature type

• GetFeature

– Delivers an instance of a feature

6.3 GML

– Delivers an instance of a feature

– Supports spatial and non-spatial selections

<wfs:Query typeName="AX_Gebaeude">

<ogc:Filter>

<ogc:PropertyIsEqualTo>

<ogc:PropertyName>weitereGebaeudefunktion</ogc:PropertyName>

<ogc:Literal>1170</ogc:Literal>

</ogc:PropertyIsEqualTo>

</ogc:Filter>

</wfs:Query>

(56)

• Extensible Stylesheet Language for Transformation

• Programming language to

transform XML documents

6.4 XSLT

transform XML documents

• Computational complete

• Based on tree structure of XML documents

• Used to define transformation rules

• Is a declarative and functional programming language

(57)

• XSLT programs (XSLT stylesheets) are XML documents themselves

• Stylesheets are read by XSLT processors; based on the stylesheets' rules the XSLT processors then transforms input documents into output

6.4 XSLT

then transforms input documents into output documents

(58)

• A transformation consists of transformation rules (templates) with the following structure

– An XPath-based pattern

– Instructions for constructing the target tree

• Patterns select nodes of the source tree

6.4 XSLT

• Patterns select nodes of the source tree

• From these nodes the instructions generate parts of the target tree

• Frame of a transformation (XSLT stylesheet):

<?xml version="1.0" encoding="ISO-8859-1"?>

<xsl:stylesheet xmlns:xsl=http://www.w3.org/1999/XSL/Transform version="1.0">

<xsl:output method="xml" />

<!– rules -->

</xsl:stylesheet>

(59)

• Main construct is the template

6.4 XSLT

<xsl:template match="...">

...instructions...

</ xsl: template>

– If several transformation rules are applicable, the most specific one is

applied

– Within a template

numerous instructions may occur

(60)

• <xsl:apply-templates

select = ... mode = ...>

... parameters may occur... </xsl:apply-templates>

– Explicit call of templates

– In the select attribute specification of an XPath

6.4 XSLT

– In the select attribute specification of an XPath expression

– With it selection of the nodes to be processed

– If no select element is present, all direct child nodes are processed

– With the mode parameters further node selection can be performed

(61)

• <xsl:value-of select = .../>

– Generates a string at the current position in the output tree

– String can be the value of a node or of a defined variable

6.4 XSLT

variable

– Select attribute selects node, variable, or parameter whose value is to be used

(62)

• <xsl:for-each select = ...> ...instructions...

</xsl:for-each>

– Iteration instructions within a template definition – All instructions within this statement are applied to

all specified nodes

6.4 XSLT

all specified nodes

– Select attribute selects nodes

• <xsl:text>

– Generates static text in the result tree

(63)

• <xsl:choose>

– Frame for sequence of queries – <xsl:when test = ...>

...instructions... </xsl:when>

– Queries are finished with <xsl:otherwise>

6.4 XSLT

– Queries are finished with <xsl:otherwise>

– Those query is selected whose condition as first yields true

• <xsl:if test = ...> ...instructions... </xsl:if>

– Conditional execution of instructions – Test attribute contains condition

(64)

• For illustration: excerpt from "xslt.xsd" to describe "choose"

6.4 XSLT

<element name="when" type="xsl:conditional-template"

maxOccurs="unbounded"/>

<element name="otherwise" type="xsl:template-with-space"

minOccurs="0"/>

</complexType>

<complexType name="conditional-template" base="xsl:template-with-space"

derivedBy="extension">

</complexType>

<complexType name="template-with-space" base="xsl:template"

derivedBy="extension">

</complexType>

(65)

• Example for the use of XSLT

– Transformation of XML-compliant extracts of the digital landscape model (DLM25)

into TK25-like graphics (see section 3.2) – Here: derivation rule for local roads

6.4 XSLT Example

– Here: derivation rule for local roads

(are drawn as white lines with a narrow purple boundary)

– Template scans data for local roads and generates drawing commands

(66)

• A (fairly short) road in the given landscape dataset

6.4 XSLT Example

<gml:name>Badstrasse</gml:name>

<gml:centerLineOf>

<gml:coord>

<gml:X>4437952.980</gml:X>

<gml:Y>5331812.550</gml:Y>

</gml:coord>

<gml:coord>

<gml:X>4437960.070</gml:X>

<gml:Y>5331818.450</gml:Y>

</gml:coord>

<gml:coord>

<gml:X>4437967.200</gml:X>

<gml:Y>5331825.410</gml:Y>

</gml:coord>

</gml:centerLineOf>

(67)

6.4 XSLT Example

<Zustand>in Betrieb</Zustand>

<AnzahlDerFahrstreifen

Bedeutung="tatsaechliche Anzahl"> 2

</AnzahlDerFahrstreifen>

<Funktion>Strassenverkehr</Funktion>

Anliegerverkehr

</VerkehrsbedeutungInneroertlich>

<BreiteDerFahrbahn>Keine Zuweisung

</BreiteDerFahrbahn>

<Widmung>Gemeindestrasse</Widmung>

Attribut trifft nicht zu

</InternationaleBedeutung>

Attribut trifft nicht zu

</VerkehrsbedeutungUeberuertlich>

</Attribute>

</Strasse>

</AtkisMember>

(68)

• Search for local roads

6.4 XSLT Example

<xsl:template

match="/dlm:AtkisModell/dlm:AtkisMember/dlm:Strasse">

<xsl:if test="contains(dlm:Attribute/dlm:Widmung,’Gemeindestrasse’) or contains(dlm:Attribute/dlm:Widmung,’Sonstiges’)">

<xsl:call-template name="DrawPath">

<xsl:with-param name="styleclass"

select="linieNebenstrasseNahverkehrVordergrund">

</xsl:call-template>

</xsl:if>

</xsl:template> <AtkisMember>

<gml:name>Badstrasse</gml:name>

<gml:centerLineOf>

<gml:coord>

<gml:X>4437952.980</gml:X>

<gml:Y>5331812.550</gml:Y>

</gml:coord>

(69)

• Generating line signatures

6.4 XSLT Example

<xsl:template name="DrawPath">

<xsl:param name="styleclass"/>

<svg:path>

<xsl:attribute name="class"><xsl:value-of select="$styleclass"/></xsl:attribute>

<xsl:attribute name="d">

<xsl:for-each select="gml:centerLineOf/gml:coord">

<xsl:choose>

<xsl:when test="position() = 1">

<xsl:text>M </xsl:text><xsl:call-template name="getX"/>

<xsl:text> </xsl:text><xsl:call-template name="getY"/>

<xsl:text> L </xsl:text>

</xsl:when>

<xsl:otherwise>

<xsl:call-template name="getX"/>

<xsl:text> </xsl:text><xsl:call-template name="getY"/>

<xsl:if test="position() != last()"><xsl:text> </xsl:text></xsl:if>

</xsl:otherwise>

</xsl:choose>

</xsl:for-each>

</xsl:attribute>

</svg:path>

(70)

• Templates "getX" and "getY" read x and y

coordinates, transform the coordinates into map coordinates, and write it to the current position in the output tree

• Style class

6.4 XSLT Example

• Style class

“linieNebenstrasseNahverkehrVordergrund”:

• Line which is generated in the example (SVG statement):

.linieNebenstrasseNahverkehrVordergrund

{ fill: none; stroke-width: 8.5px; stroke: snow; stroke-linejoin: round}

<path class="linieNebenstrasseNahverkehrVordergrund"

d="M 8245.97 -2142.98 L 8253.65 -2146.15 8259.83 -2151.12"/>

(71)

• Scalable Vector Graphics (SVG)

• XML-based language for

describing two-dimensional, freely scalable vector graphics

6.5 SVG

freely scalable vector graphics

• Standard of the W3C

• Beside static graphics also interactions, animation, and filter applications are provided

• SVG files are relatively small and are editable with any text editor

(72)

• SVG documents are structured like XML documents

– Prolog with XML declaration and document type declaration

– Root element, including

6.5 SVG

– Root element, including

• Declaration of namespaces and

• Definition area (also for non-SVG code)

– Attributes "width" and "height" specify the width and the height of the entire graphic

– Optional attribute "viewBox" defines reference frame, specified are its left lower point and its width

(73)

– Example, declares a frame for a real estate map in the context of an A3 landscape format and a scale of

1:1000

6.5 SVG

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"

"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">

viewBox= "99269.744 150779.44 42000.0 29700.0"

xmlns:xlink= "http://www.w3.org/1999/xlink">

<defs>

.SN2028LinieFlurstueck{fill: none; stroke-width: 35; stroke-linecap: butt;

stroke-linejoin: miter; stroke: #000000;}

...

</style>

...

</defs>

...

(74)

• Several SVG elements and attributes, including

– Line between 2 points (line)

– Line connecting several points (polyline) – Rectangle (rect)

6.5 SVG

Rectangle (rect) – Circle

– Ellipse – Polygon – Path

– Text

<rect x="5" y="5"

width="50" height="25"

style="stroke: blue; fill: none;">

</svg>

(75)

• All attributes of rectangle

6.5 SVG

<!ATTLIST %SVG.rect.qname;

%SVG.Core.attrib;

%SVG.Conditional.attrib;

%SVG.Style.attrib;

%SVG.Paint.attrib;

%SVG.Color.attrib;

%SVG.Opacity.attrib;

%SVG.Graphics.attrib;

%SVG.Clip.attrib;

%SVG.Mask.attrib;

%SVG.Filter.attrib;

%SVG.GraphicalEvents.attrib;

%SVG.Cursor.attrib;

%SVG.External.attrib;

x %Coordinate.datatype; #IMPLIED y %Coordinate.datatype; #IMPLIED width %Length.datatype; #REQUIRED height %Length.datatype; #REQUIRED rx %Length.datatype; #IMPLIED

ry %Length.datatype; #IMPLIED

(76)

• Circle example (with instruction for grouping and transformation)

6.5 SVG

<g style="fill-opacity:0.7;

stroke:black;

stroke-width:0.1cm;">

<circle cx="6cm" cy="2cm" r="100"

http://luxor-xul.sourceforge.net/

style="fill:red;"

transform="translate(0,50)"/>

style="fill:blue;"

style="fill:green;"

transform="translate(-70,150)"/>

</g>

(77)

• Path instruction for complex shapes, lines and areas

– Element’s attributes include the attribute “d” for specifying the points of the path

– Attribute “d” contains further commands for the

6.5 SVG

– Attribute “d” contains further commands for the interpretation of the points

– E.g. a point may be the begin or the end of a curve or of a line

<path id="SN4100_einzelsignaturNadelholz"

d="M 130 0 L -50 0 0 -180 50 0"

fill="none" stroke-miterlimit="20"

stroke-linejoin="miter"

stroke-width="12" stroke="&baumgrün;"/>

(78)

• Commands of the path instruction

6.5 SVG

command description example

M (MoveTo) specifies the starting point of a path M20 50

Z (ClosePath) generates a closed shape Z

L (LineTo) draws a line from the current point to the specified point

L50 100 specified point

H (Horizontal LineTo)

draws a horizontal line from the current point

H75

V (Vertical LineTo) draws a vertical line from the current point V40 C (CurveTo) draws a Bézier curve from the current

point

C30 0 50 20 60 15

Q (Quadratic Bézier CurveTo)

draws a quadratic Bézier curve from the current point

Q40 0 60 20 A (Elliptical Arc) draws an elliptic arc from the current point A25 25 -30 0 1

50 -25

(79)

• Path example (with quadratic Bezier curve)

6.5 SVG

<path fill="none" stroke-width="3"

stroke="green"

d="M 20 20 l 0 -13 M 16 20 q 0 -10 -5 -10 M 12 20 q 0 -6 -4 -6 M 12 20 q 0 -6 -4 -6 M 24 20 q 0 -10 5 -10 M 28 20 q 0 -6 4 -6"

id="Pflanzensymbol"/>

(80)

• Path example (with grouping command and filled areas)

6.5 SVG

250.0 250.0 Z“ fill= "#FFFFFF"/>

<path d="M -200.0 145.0 L -118.0 88.0 -94.0 97.0 -94.0 72.0 -148.0 72.0 -148.0 -27.0 -94.0 -27.0 -94.0 -152.0 33.0 -200.0 161.0 -134.0

161.0 80.0 200.0 115.0 132.0 200.0 62.0 150.0 62.0 72.0 0.0 72.0 0.0 150.0 -73.0 200.0 Z“ fill= "#FF0000"/>

<path d="M 0.0 -27.0 L 0.0 -119.0 62.0 -95.0 62.0 -27.0 Z"

fill= "#FFFFFF"/>

</g>

(81)

• Text instruction for text placement

– Beside being a graphic element, in SVG text is also available as a text element

6.5 SVG

element

– Several attributes,

including “x” and “y” for positioning

– Texts can be translated and turned

– Orientation, alignment, font stretch may be

specified among others

[SX08]

(82)

• Text example

6.5 SVG

<defs>

<![CDATA[ text {font-family:verdana,sans-serif;

font-size:40px; font-weight:bold;}]]>

</style>

</defs>

http://svg.tutorial.aptico.de/

</defs>

<circle cx="150" cy="100" r="90“

style="fill:none; stroke:black;" />

<text class="big" x="110,135,160" y="70,110,150"> SVG

</text>

<text class="big" x="110,135,160" y="70,110,150“

dx="-10,-10,-10" style="fill:red;"> SVG

</text>

(83)

• Grouping instruction “g” to group elements

– Attributes of grouped elements can be specified altogether, e.g. style attributes

6.5 SVG

<circle cx="6cm" cy="2cm" r="100" style="fill:red;"

– Groups can be named

<circle cx="6cm" cy="2cm" r="100" style="fill:red;"

<circle cx="6cm" cy="2cm" r="100" style="fill:blue;"

<circle cx="6cm" cy="2cm" r="100" style="fill:green;"

transform="translate(-70,150)"/></g>

(84)

– Also different elements may be grouped

6.5 SVG

<path d="M-250.0 310.0 L -250.0 -190.0 0.0 -310.0 250.0 -190.0 250.0 310.0 Z"

fill= "#00FFFF"/>

<text font-family= "Arial" font-weight= "bold"

font-size= "420" stroke= "#FFFFFF"

fill= "#FFFFFF" x= "-130.0" y="150.0">

• With the "use" element an instance of a named element (e.g. of a group) is created

fill= "#FFFFFF" x= "-130.0" y="150.0">

P

</text>

</g>

<use transform="translate(135463.0,173871.7)"

xlink:href="#SN3309SymbolParkhausParkdeck"/>