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1.4.7. Interactivity in Thematic Maps

When producing a static thematic map you have to choose the data visualisation type right at the beginning of the production process. That means that you have to choose a representation type and eventually a classification type and visualise the data, according to your choice, in the map. Even if there exist several possibilities to visualise the data in an appropriate way in a map, you have to choose one of them and apply it to the data.

Within the field of interactive thematic maps we have the possibility to leave the choice for an appropriate data representation to the user. Of course, you have to choose the representation types that visualise best the given data. But if there are several ideal methods (choropleth map, diagrams, etc.) for the best visualisation, you are able to leave the final choice to the user. You can even leave the choice of which data should be visualised to the user.

To get an idea of some of the mentioned possibilities, explore the following interactive map.

Example of an      interactive thematic mapExample of an interactive thematic map (Schnabel 2008)

Can you name three functions that allow to change the visualisation parameters of the presented map? (Click here for more information)

Two of the most popular features of interactive thematic maps are that the user can choose the variables that will be visualised in the map and the classification method that will be applied to the data, including the number of classes.

You can explore a second interactive example that include these popular features:

An example of an         interactive thematic mapAn example of an interactive thematic map (Isakowski 2004)

In the previous chapter we said that (1) a continuous representation of data amounts is better because the exact values are visualised in the map. But we also mentioned that (2) it is better to classify the data because the human eye has a limited ability to discriminate a large number of different areal symbol shades. For printed maps you have to choose one of these two methods and create the map according to your decision.
However, for interactive screen maps you are able to combine these two methods. On the one hand you can create e.g. a choropleth map using intervals and on the other hand you can show the user the exact value for each area by e.g. implementing a mouse over or a click effect, etc.

Both presented maps contain the combination of these two methods. Did you already recognize how the examples integrated these methods? If not, have a second look at the examples and concentrate on these methods.

Here are the solutions how the examples integrated the two methods. (Click here for more information)

We will not go into further details of interactivity for thematic maps because there is a large number of functions that can be implemented into a thematic map. We only want you to explore the example on the right, which is very rich of interactive tools for thematic maps, to get an idea what interactivities may be implemented in a thematic map. remark

The application allows you to load your own dataset, choose a diagram type and create a map out of your defined settings.

Application rich of interactivitiesApplication rich of interactivities (Schnabel 2006)

If you are interested in examples that show possibilities of the interaction between the content of a thematic map and its legend, have a look at the Homepage of Ellsiepen. There you find several examples that deal with interactive legends in thematic maps.

Exercise

We only presented you a few possible interaction parts that could be implemented into an interactive thematic map. There are a lot more possibilities how to design a thematic map interactively.

There exist a lot of interactive thematic maps in the Internet. We now want you to search the Internet for one of them. Write a short (about 1/2 A4 page) essay about the interactive parts of your chosen maps. How is the thematic cartography aspect realised? Do you miss some interactivities or are there some interactivities which could be realised in a better way? Hand in your essay to your tutor.



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