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Cartography in internet-based view services : methods to improve cartography when geographic data from several sources are combined

Olsson, Per Ola LU (2011) In Seminar series NGEM01 20102
Dept of Physical Geography and Ecosystem Science
Abstract
We live in an information intensive society and geographic data are part of this information. These geographic data are used by private persons to plan holiday trips or to find the way to business meetings. Companies utilize geographic data in fields such as forestry, construction work, and tourism. Local municipalities require geographic data for planning purposes, and in the academic world much research is based on geographic data. To enable sharing of these data, searching, viewing, and downloading are facilitated by web-based services following common standards. These services are part of, and regulated by Spatial Data Infrastructures (SDI). An important component of an SDI is a geoportal. That is a web site acting as a gateway to web... (More)
We live in an information intensive society and geographic data are part of this information. These geographic data are used by private persons to plan holiday trips or to find the way to business meetings. Companies utilize geographic data in fields such as forestry, construction work, and tourism. Local municipalities require geographic data for planning purposes, and in the academic world much research is based on geographic data. To enable sharing of these data, searching, viewing, and downloading are facilitated by web-based services following common standards. These services are part of, and regulated by Spatial Data Infrastructures (SDI). An important component of an SDI is a geoportal. That is a web site acting as a gateway to web services that enable a user to search, view, and download geographic data.

In this master thesis the main focus is on view services. If these view services have limited symbology options they may prevent geoportals from reaching their full potential. It might be so that all data required for a map are found from different sources, but limited symbology options prevent a user from designing a legible map. This situation can be improved by allowing user-defined symbology or with a larger number of symbologies available from a service. Cartography can also be improved by methods that enable a user to control symbology to a larger extent.

To facilitate development of methods to improve cartography when data from several sources are combined and viewed in a geoportal a test bed, the Cartographic enhanced geoportal (CEG), is implemented in this study. Two methods are implemented in CEG. The polygon overlay method enables polygon features to be overlaid other data without hiding underlying information; this is achieved by symbolizing polygons with boundary and icons. The colour saturation method enables a user to invoke visual hierarchies in a map by deemphasizing less important information.

Another potential problem in view services is maps that are difficult to read due to excessive amount of information. One approach to solve this problem is to identify areas with poor legibility in a map and apply generalization operations on these areas; that is more efficient than applying generalization on the entire map A study was performed to investigate if clustering techniques can be used to identify areas that are difficult to read. The density based DBSCAN clustering algorithm was implemented and tested. The study shows a promising result; however, a more extensive investigation must be performed to draw any conclusions. (Less)
Abstract (Swedish)
Populärvetenskaplig sammanfattning
Vi lever idag i ett informationssamhälle och delar av denna information är geografisk. Denna geografiska information kan användas för att skapa kartor efter egna önskemål och för specifika användningsområden. Genom att ansluta till en webbsida som tillhandahåller visningstjänster av kartor kan en användare välja vilken information som ska vara med i en karta och vilka symboler som ska användas för informationen som visas.

En webbsida som ger tillgång till visningstjänster som gör det möjligt att skapa egna kartor kallas geoportal. Genom att ansluta till en geoportal kan kartor skapas efter egna önskemål. Detta är en stor skillnad mot karttjänster som exempelvis eniro.se och hitta.se där kartorna... (More)
Populärvetenskaplig sammanfattning
Vi lever idag i ett informationssamhälle och delar av denna information är geografisk. Denna geografiska information kan användas för att skapa kartor efter egna önskemål och för specifika användningsområden. Genom att ansluta till en webbsida som tillhandahåller visningstjänster av kartor kan en användare välja vilken information som ska vara med i en karta och vilka symboler som ska användas för informationen som visas.

En webbsida som ger tillgång till visningstjänster som gör det möjligt att skapa egna kartor kallas geoportal. Genom att ansluta till en geoportal kan kartor skapas efter egna önskemål. Detta är en stor skillnad mot karttjänster som exempelvis eniro.se och hitta.se där kartorna redan är ”färdiga”. Via en geoportal kan exempelvis en kommun som vill hitta en lämplig plats för att bygga en ny industri skapa en karta där olämpliga områden, t.ex. olämpliga jordarter, skyddade områden, och närområde runt tätorter markeras. En sådan karta kan sedan användas som beslutsunderlag. En privatperson som planerar en semesterresa kan exempelvis ta med antal dagar med åska i sin karta för att hitta områden med liten åskrisk.

Det finns emellertid begränsningar som gör att geoportaler inte är lika användbara som de skulle kunna vara. Ofta är det inte möjligt för en användare att bestämma vilka symboler som ska användas för den geografiska informationen. Det kan leda till att viktig information döljas av annan information när geografiska data från flera tjänster visas i en och samma karta. Detta kan förbättras genom att ge en användare mer frihet när det gäller att bestämma vilka symboler som ska användas. Situationen kan också förbättras genom att designa symboler som gör att det blir möjligt att kombinera information från flera tjänster.

I denna uppsats presenteras en utvecklingsmiljö för att testa metoder som gör det enklare att skapa kartor som är lättlästa i en geoportal. En metod som gör att inte information döljs av annan information är att ytor visas med en kantlinje och ikoner (ytmönstringssymboler) istället för att heltäckande fyllning. En annan metod som gör det lättare att skapa lättlästa kartor är att tona ner mindre viktig information i en karta. En metod att identifiera svårlästa områden i en karta presenteras också. Genom att hitta svårlästa områden och göra dessa mer lättlästa kan en bättre karta skapas. (Less)
Please use this url to cite or link to this publication:
author
Olsson, Per Ola LU
supervisor
organization
alternative title
Kartor skapade över internet
course
NGEM01 20102
year
type
H2 - Master's Degree (Two Years)
subject
keywords
geography, physical geography, cartography, geoportal, view service, WMS, symbology, legibility, geografi, naturgeografi, kartografi, visningstjänst, symbolsättning, läsbarhet.
publication/series
Seminar series
report number
202
language
English
id
3049302
date added to LUP
2012-09-04 16:27:06
date last changed
2012-09-04 16:27:06
@misc{3049302,
  abstract     = {We live in an information intensive society and geographic data are part of this information. These geographic data are used by private persons to plan holiday trips or to find the way to business meetings. Companies utilize geographic data in fields such as forestry, construction work, and tourism. Local municipalities require geographic data for planning purposes, and in the academic world much research is based on geographic data. To enable sharing of these data, searching, viewing, and downloading are facilitated by web-based services following common standards. These services are part of, and regulated by Spatial Data Infrastructures (SDI). An important component of an SDI is a geoportal. That is a web site acting as a gateway to web services that enable a user to search, view, and download geographic data. 

In this master thesis the main focus is on view services. If these view services have limited symbology options they may prevent geoportals from reaching their full potential. It might be so that all data required for a map are found from different sources, but limited symbology options prevent a user from designing a legible map. This situation can be improved by allowing user-defined symbology or with a larger number of symbologies available from a service. Cartography can also be improved by methods that enable a user to control symbology to a larger extent.

To facilitate development of methods to improve cartography when data from several sources are combined and viewed in a geoportal a test bed, the Cartographic enhanced geoportal (CEG), is implemented in this study. Two methods are implemented in CEG. The polygon overlay method enables polygon features to be overlaid other data without hiding underlying information; this is achieved by symbolizing polygons with boundary and icons. The colour saturation method enables a user to invoke visual hierarchies in a map by deemphasizing less important information. 

Another potential problem in view services is maps that are difficult to read due to excessive amount of information. One approach to solve this problem is to identify areas with poor legibility in a map and apply generalization operations on these areas; that is more efficient than applying generalization on the entire map A study was performed to investigate if clustering techniques can be used to identify areas that are difficult to read. The density based DBSCAN clustering algorithm was implemented and tested. The study shows a promising result; however, a more extensive investigation must be performed to draw any conclusions.},
  author       = {Olsson, Per Ola},
  keyword      = {geography,physical geography,cartography,geoportal,view service,WMS,symbology,legibility,geografi,naturgeografi,kartografi,visningstjänst,symbolsättning,läsbarhet.},
  language     = {eng},
  note         = {Student Paper},
  series       = {Seminar series},
  title        = {Cartography in internet-based view services : methods to improve cartography when geographic data from several sources are combined},
  year         = {2011},
}