A Web Service to personalise Map Colouring

17.11.09 A Web Service to personalise Map ColouringJoerg Steinruecken

A Web Service to personalise Map Colouring

Joerg SteinrueckenDepartment of Geoinformation

Institute of Geodesy and GeoinformationUniversity of Bonn

17.11.09A Web Service to personalise Map Colouring

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Joerg Steinruecken

Motivation

• World Wide Web offers geospatial data from many different sources

• „Mapping on Demand“: Creating maps– in real time– by combining data from different sources– for individual purposes– independent of time and place

• Problems:– Portrayal of data from different sources conflict


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Joerg Steinruecken

Personalisierung BefragungTour 1

Tour 2

Tour 4

Tour 5

Tour 6

Tour 7

Tour 3

Legend


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Joerg Steinruecken

Motivation

• World Wide Web offers geospatial data from many different sources

• „Mapping on Demand“: Creating maps– in real time– by combining data from different sources– for individual purposes– independent of time and place

• Problems:– Portrayal of data from different sources conflict– Perceptibility is influenced by

• Users‘ visual system (colour vision impairment)• Outer effects

– Device specific colour reproduction– Environment (e.g. dark room or sunlight)


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Joerg Steinruecken

Stating the problem

• Given– Background: Topographical Map which has a fixed

graphical representation

– Overlay: Objects O1 … On which can be portrayed by users

• Searching portrayal options of objects O1 … On

• Postulations– Conciseness: Visual distinguishability

• of objects O1 … On among each other

• of objects O1 … On from the topographic map

• for all users and on all devices

– Solution „on demand“– Access without technical barriers


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Joerg Steinruecken

Outer Frame

• Service-oriented architecture• Geospatial data provided by standardised services

– Open Geospatial Consortium (OGC) Web Map Service (WMS) Specification

– OGC Symbology Encoding (SE) / Styled Layer Descriptor (SLD) Specification


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Joerg Steinruecken

Statement

• Portrayal– Options: Visual variables– Most important variable: Colour– Problem of distinguishability is reduced to the

identification of well distinguishable colours– Colours are adjusted to a specific user and his

device

• Colours provided by a Web Service


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Joerg Steinruecken

Stating the problem with colours

• Given– Background: Topographical Map which contains

m colours

– Overlay: Objects O1 … On which can be portrayed by users

• Searching n colours for objects O1 … On

• Postulations– Conciseness: Visual distinguishability

• of colours of objects O1 … On among each other

• of colours of objects O1 … On from the colours of the topographic map

• for all users and on all devices

– Solution „on demand“– Access without technical barriers


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Joerg Steinruecken

Domain

Architecture

ServerClient

Browser Webserver

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy


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Joerg Steinruecken

Domain

Architecture - Personalisation

ServerClient

Browser Webserver

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy


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Joerg Steinruecken

Personalisation

• Creation of user profiles (user name, password,…)• Getting personal data

– Colour vision impairment• specified by users• Users have to evaluate test images

– Display‘s colour reproduction and ambient light• Display calibrated?• Visual calibration by gamma adjustment• Users have to evaluate test images


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Joerg Steinruecken

Domain

Architecture – Map request

ServerClient

Browser Webserver

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy


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Joerg Steinruecken

Domain


ServerClient

Browser Webserver

Web Map Client

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy


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Joerg Steinruecken

Domain


ServerClient

Browser Webserver

Web Map Client

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

ProxyWMS-URL

WMS-URL


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Joerg Steinruecken

Domain


ServerClient

Browser Webserver

Web Map Client

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy

GetCapabilties


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Joerg Steinruecken

Domain


ServerClient

Browser Webserver

Web Map Client

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy

SE


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Joerg Steinruecken

Domain


ServerClient

Browser Webserver

Web Map Client

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy

SE-URL

SE-URL

SE


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Joerg Steinruecken

Domain


ServerClient

Browser Webserver

Web Map Client

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy

GetMap

SE


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Joerg Steinruecken

Domain


ServerClient

Browser Webserver

Web Map Client

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy

GetMap

SLD=SE-URL

SE


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Joerg Steinruecken

Domain


ServerClient

Browser Webserver

Web Map Client

Web Map Client

Server

(SLD-)WMS

Geodata

Server

User DataPersonali-

sation

Webserver

(Service)

Colouring

Proxy


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Joerg Steinruecken

Approach of colouring

Visual Distinguishability

Colour space, providing an appropriate metric(visual equidistance)

Formulation of an optimisation problem:Maximise the minimal distance between colours

Solution on demand

Modelling the colour space: 3D-Polyhedron


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Process of colouring

sRGB

Standard-RGB


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sRGB XYZ

CIE-XYZ colour space


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sRGB XYZ CIELUV

CIE L* u* v* colour space


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Joerg Steinruecken


sRGB XYZ CIELUV MAXMIN


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Joerg Steinruecken


sRGB XYZ CIELUV MAXMIN


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Joerg Steinruecken

Optimisation problem

d

nlk ,...,1;9,...,1 0 llTk bXn

ijnmjni ;,...,1,,...,1

2, ji YX

),( XFY

F Set of m given colours

X Set of n colours which have to be determined

lTk bn , Parameters of hyperplanes which form

the polyhedron

maximise

subject to dYX ji 2

,

Euclidean Distance

objective

constraints


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Joerg Steinruecken

Problem characteristics

• Nonlinear problem– Large number of local optimal solutions– Efficient algorithms find a locally optimal solution,

but usually not the globally optimal solution

Global Optimum

Local Optima

Rastrigins function (source: Matlab)


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Behaviour of efficient algorithms

)(xf

x

Local OptimumGlobal Optimum

Fundamental importance of starting points‘ location


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Algorithm

Finding appropriate starting points

Method of local optimisation

Detect suboptimal solutions

Nearly global optimal solution

S1

S2

S3


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Joerg Steinruecken

• Observation: To use the colour space in the best possible way, the majority of points have to lie on the polyhedron‘s boundary.

• Conclusion: Points which are placed on the boundary are well suited as starting points

S1: Appropriate starting points


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S3: Detect suboptimal solutions

Given points

Voronoi vertices

intersection ofVoronoi edgesand polygon

Vertices ofthe polygon

• Find an improvement• Candidats are given by the Voronoi-Diagram• Example in 2D:


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Personal information

• Incorporation of users‘ personal information as constraints – Color vision impairment: Finding colours in a

plane– Colour reproduction & ambient light: Clipping

the colour space


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Joerg Steinruecken

Personalisierung BefragungTour 1

Tour 2

Tour 4

Tour 5

Tour 6

Tour 7

Tour 3

Legend


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Conclusions

• Concise maps by selection of well distinguishable colours

• Formulation of an optimisation problem– distinguishability = Euclidean distance

• Efficient identification of a nearly optimal solution

• Algorithm: Find appropriate starting points, local optimisation method, geometric evaluation

• Adaptation to users‘ individual requirements• Usable as Web Service• Prototype will shortly be available on

http://colour.ikg.uni-bonn.de

17.11.09 A Web Service to personalise Map ColouringJoerg Steinruecken

Thank you for your attention

A Web Service to personalise Map Colouring

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