Geospatial data integration and visualisation using open standard

Gilles TALADOIRE

University of New Caledonia (UNC)TIARE Computer Science LaboratoryNew Caledonia

a project with IRDThe French scientific research institutefor developmentLATICAL Remote Sensing LaboratoryNew Caledonia

Where is New Caledonia ?

Environmental Information System

Data AcquisitionRemote SensingGround Sensor

Data Archiving :Conception

StorageExtraction

User InterfaceData Processing and Analysis

System integration : From acquisition to visualisation

satellite sensor, aerial sensor, ground sensor==> heterogeneous data (textual, numerical, vector, images, …)==> heterogeneous formats

conceptual modelling, storage and extraction==> heterogeneous systems (GIS, DBMS, …)==> heterogeneous formats

Connected systems : expert systems, neural networks,multi-agents systems, data mining systems, imageprocessing and analysis, simulations, scientific model, …==> heterogeneous systems==> heterogeneous formats

Data visualisationadapted to the different users of an environmental projectavailable on Internet, graphically

==> Heterogeneous Data, Formats and Systems

Independent systems (generally)==> incompatibility or incoherence in this process

Many partners involved in environmental projects(expert firm, administration, research institute, …)

==> Not the same methods Not the same software

Not a single place

==> The generalised use of standards

Existing standardisation initiatives

In the domain of geospatial information : the Technical Comity ISO 211 :

the standardisation in the field of digital geographic information the OpenGIS consortium

the definition of specification to define transparent access toheterogeneous geodata and geoprocessing resourcesin a networked environmentGeographic Markup Language (GML)

In the domain of the internet : World Wide Web Consortium (W3C) Extensible Markup Language (XML)

(the universal format for structured documents and data on the Web) Scalable Vector Graphics (SVG)

(An application of XML for describing two-dimensional graphics)

Architecture for system integration

Data Acquisition :

Remote SensingGround Sensor

Data Archiving :Conception

StorageExtraction

User InterfaceData Processing and Analysis

System integration : From acquisition to visualisation

GML SVGGMLGML

==> The use of GML as common data interface

==> The use of SVG as visualisation solution

Creation of Import/Export module

GIS /Data Base

DataMining Simulation

DataProcessing

ImageProcessing

LearningSystem

ScientificModel

…

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Visualisation : from GML to SVG

Geographic DataDescription Language

Vector GraphicsDescription Language

Transformation to dofor map display

XML Schema

W3C

GML

OG

C

SVG

W3C

XML

W3C

Correspondence between objects

Geometric objet Correspondence

GML SVG<Point> To be determined : rectangle, circle, icon at the point<LineString> <polyline><Box> <rect><LinearRing> Used with <svg:polygon><Polygon> <polygon><MultiPoint> To be determined : rectangle, circle, icon at the point<MultiLineString> A group <g> of <svg:polyline><MultiPolygon> A group <g> of <svg:polygon>’

Feature Correspondence

GML SVGGML Feature

<Xxx><gml:name>feature_name</gml:name>…</Xxx>

SVG group

<g class="Xxx" id="name">…</g>

Geometric property :a point in the example

<Xxx>…<gml:location> <gml:Point> <gml:Coord> <gml:x>valuex</gml:x> <gml:y>valuey</gml:y> </gml:Coord> </gml:Point> </gml:location>…</gml:location>

Base element as in the table :a rectangle in the example

<rect x="valuex" y="valuey" heigth="10" width="10" class="Xxxlocation"/>

Non-geometric property :text, integer, decimal

<gml:name>feature_name</gml:name>

Text as legend

<text x="valuex" y="valuey"class="Xxxname">feature_name</text>

The use of the 'class' property of graphical objects to identify the element originThe properties of one feature are grouped with the <g> elementThe features collections are to group with the <g> elementThe non-geometric properties could be visualised as text on the map like a legend of the object

Example : A water tank has a name and a Point location

GML SVG<WaterTank> <gml:name>Drueulu1</gml:name> <gml:location> <gml:Point> <gml:Coord> <gml:x>512.0</gml:x> <gml:y>362.0</gml:y> </gml:Coord> </gml:Point> </gml:location></WaterTank>

<g class="WaterTank" id="Drueulu1"><rect y="357" x="507" height="10" width="10" class="WaterTanklocation"/><text y="362.0" x="512.0"class="WaterTankname">Drueulu1</text></g>

Display style

No style in GML 2.0

In SVG, three common usage for styling : directly in the SVG content SVG content generated as the output from XSLT transformation SVG content styled with CSS

==> Styling with CSS style sheet using the class names given to SVGelements :

flexible to change the map presentationeasy to do

Example

style sheet "watertank.css"

<g class="WaterTank" id="Drueulu1"><rect y="357" x="507" height="10" width="10" class="WaterTanklocation"/><text y="362.0" x="512.0" class="WaterTankname">Drueulu1</text></g>

.WaterTank {display:inline}

.WaterTanklocation {fill:red;stroke:blue;stroke-width:2; visibility:visible}

.WaterTankname {fill:black; visibility:visible}

part of SVG file SVG rendering

Fusion

GML Document

Style Sheet

SVG DocumentGenerator

The generic SVG generator :- a transformation XSL : XSLT designed speciallyor- a program that parse the XML file : for special processing

XLST transformations generic at two levels :- the application uses only geometric properties defined in the GML features schema, a general XSLT style sheet can be defined and used for all applications of this kind.- the GML application schema use specific geometric properties, the defined XSLT style sheet can be only use with the applications using this schema.

Extensions

Functionality to add in a generic way : The interactivity to manage layers, for zoom and moving functions The automatic generation of legends The use of links and associations of GML

- to visualise the links between the features to show dependencies Example : a water tank supply water to a village, a line is drawn from the tank to the village.

- to establish hyperlink between graphical elements The GML schema parsing :

- to develop a style sheet editor which propose features and properties of the schema- to realise a automatic style sheet generator from the schema

The management of temporal series to animate objects on the map

Conclusion

First stepSpatial data visualisation with a correspondence

between descriptive data and graphical data

Global projectto integrate systems with general use of GML as standard format

Thanks to :

I3S laboratory (University of Nice-Sophia Antipolis - CNRS)to invited me from september 2000 to june 2001