12 Geographical Data Visualization on Mobile Devices
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technique based on displaying arrows coupled with labels for distance indication. In
a subsequent work [9], we compared Halo with two other techniques based on exploiting size and body length of arrows, respectively, to inform about the distance of
objects. In our study, arrows allowed users to order off-screen objects faster and more
accurately according to their distance, while Halo allowed users to better identify the
correct location of off-screen objects.
12.3 Supporting User’s Navigation in the Field
Navigation can be generally defined as the process whereby people determine where
they are, where everything else is, and how to get to particular objects or places [20].
Helping users navigate the geographical area they are in is a typical goal of systems
supporting activities in the field. For example, it is a key service of mobile guides [5],
applications that exploit information such as user position, place, current time, and
task, to provide users with information and services related to a specific geographical
area. A number of the proposed techniques are based on the visualization of 2D
maps representing the considered geographical area but alternative solutions have
also been investigated, especially to provide users with directions to reach specific
objects or places.
12.3.1 2D Map-based Techniques
2D maps provide information about the geographical area the users are in. By
exploiting positioning technologies such as GPS (global positioning system), they
can highlight the user’s current position by means of a graphical symbol. Furthermore, the positions of objects and other people can be presented. Additionally, maps
can show routes and landmarks (i.e. distinctive features of an environment, such as
churches and squares, that can be used as reference points during navigation) for
reaching specific objects or places in a geographical area.
Most of the research results presented in Sect. 12.2 are also significant in the
design of maps for navigation. For example, by investigating the effect of map generalization on user’s performance in route-following tasks in a geographical area,
Dillemuth [13] found that a generalized map was more effective than an aerial photograph (Fig. 12.6). Indeed, users took less time to complete tasks and performed
less zooming operations in the former rather than in the latter condition. However,
Dillemuth also points out that missing or erroneous information in a map cause confusion and errors in navigating an area, thus suggesting that an accurate aerial map
with a lot of detail would be preferable to a generalized but outdated map.
Baus et al. [6] studied how to perform map adaptation for pedestrian navigation according to user’s walking speed and accuracy of positional information.
Figure 12.7(a) presents an example map for a slowly moving user and unprecise
positional information, whereas Fig. 12.7(d) shows a map for exact positional information at higher speed. The precision of positional information is encoded in the size
of the dot that represents user’s current position on the map. A decreasing positional
269
technique based on displaying arrows coupled with labels for distance indication. In
a subsequent work [9], we compared Halo with two other techniques based on exploiting size and body length of arrows, respectively, to inform about the distance of
objects. In our study, arrows allowed users to order off-screen objects faster and more
accurately according to their distance, while Halo allowed users to better identify the
correct location of off-screen objects.
12.3 Supporting User’s Navigation in the Field
Navigation can be generally defined as the process whereby people determine where
they are, where everything else is, and how to get to particular objects or places [20].
Helping users navigate the geographical area they are in is a typical goal of systems
supporting activities in the field. For example, it is a key service of mobile guides [5],
applications that exploit information such as user position, place, current time, and
task, to provide users with information and services related to a specific geographical
area. A number of the proposed techniques are based on the visualization of 2D
maps representing the considered geographical area but alternative solutions have
also been investigated, especially to provide users with directions to reach specific
objects or places.
12.3.1 2D Map-based Techniques
2D maps provide information about the geographical area the users are in. By
exploiting positioning technologies such as GPS (global positioning system), they
can highlight the user’s current position by means of a graphical symbol. Furthermore, the positions of objects and other people can be presented. Additionally, maps
can show routes and landmarks (i.e. distinctive features of an environment, such as
churches and squares, that can be used as reference points during navigation) for
reaching specific objects or places in a geographical area.
Most of the research results presented in Sect. 12.2 are also significant in the
design of maps for navigation. For example, by investigating the effect of map generalization on user’s performance in route-following tasks in a geographical area,
Dillemuth [13] found that a generalized map was more effective than an aerial photograph (Fig. 12.6). Indeed, users took less time to complete tasks and performed
less zooming operations in the former rather than in the latter condition. However,
Dillemuth also points out that missing or erroneous information in a map cause confusion and errors in navigating an area, thus suggesting that an accurate aerial map
with a lot of detail would be preferable to a generalized but outdated map.
Baus et al. [6] studied how to perform map adaptation for pedestrian navigation according to user’s walking speed and accuracy of positional information.
Figure 12.7(a) presents an example map for a slowly moving user and unprecise
positional information, whereas Fig. 12.7(d) shows a map for exact positional information at higher speed. The precision of positional information is encoded in the size
of the dot that represents user’s current position on the map. A decreasing positional