clutter reduction methods for point symbols in …...1. aim of the study: clutter reduction for map...

Jari Korpi, Paula Ahonen-Rainio28.8.2013

Clutter Reduction Methods for Point Symbols in Map Mashups

Contents

1. Aim of the study: Clutter reduction for map mashups2. Classification of the clutter reduction methods3. Criteria for evaluating the methods4. Evaluation of the methods against the criteria5. Example6. Conclusions

9/20/2013Department of Real Estate, Planning and Geoinformatics

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Map mashups

= Content from different sources are overlaid on top of each other,typically thematic information on top of a background map

= Often interactive tools for exploring the thematic information


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Map mashups

Map mashups can vary in...

Common problem with mashups: Clutter of symbols


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symbology density usage

Clutter reduction in map mashups

We needed to find methods that are suitable for reducing clutter in an interactive map mashup

To be successful in choosing a method for a cluttered map the characteristics and needs of the case

andthe strengths and limitations of different methods

must be known


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Clutter reduction in map mashups

Because map mashups have characteristics from both maps and information visualization, methods from both disciplines should be considered

Maps generalization operatorsInformation visualization clutter reduction methods


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Classification of the methods


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Map Mashups Cartography Informationvisualisation

Selection Selection Filtering

Refinement Refinement Sampling

Displacement Displacement Displacement

Aggregation Aggregation Clustering

Typification Typification Clustering

Symbolisation Symbolisation

Classification

Change size

Change opacity

Spatial distortion Topological distortion

Animation Animation








Classification

Change size

Change opacity


Animation Animation








Classification

Change size

Change opacity


Animation Animation








Classification

Change size

Change opacity


Animation Animation

cluttered

changing

Criteria for evaluating the methods


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Map Mashups Cartography (McMaster & Shea 1992)

Information visualisation (Ellis & Dix 2007)

Reduces complexity Reducing complexity

Avoids hidden symbols Avoids overlap

Keeps spatial information Maintaining spatial accuracy Keeps spatial information

Can be localised Can be localised

Is scalable Is scalable

Is controllable Is adjustable

Keeps attribute values Maintaining attribute accuracy Can show point/line attribute

Can access individual items Can discriminate points/lines

Improves aesthetic quality Maintaining aesthetic quality

Keeps logical hierarchy Maintaining a logical hierarchy

























































































































Strengths and limitations of the methods


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yes

mainly

partially

no

Example: News map with pictographic symbolsPrimary criteria for the case:1.Effect must be targetted to cluttered areas2.Individual items must be accessible3.Attribute values must be shown

To supplement the limitations of the primary method


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Example: News map with pictographic symbols


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Conclusions

For map mashups, clutter reduction methods and requirements are derived from cartography and information visualization

Knowing the general strengths and limitations of the methods helps in finding the suitable methods for each case

None of the clutter reduction methods is perfect; each has its strengths and limitations


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Thank you!

Further information:

[email protected]

The Cartographic Journal 50(3) pp. 257-265.


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mailto:[email protected]

clutter reduction methods for point symbols in …...1. aim of the study: clutter reduction for map...

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