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Human Interaction with Animated Maps:
The portrayal of the passage of time
Terje Midtbø1, Keith C. Clarke2 and Sara I. Fabrikant3
1 Division of Geomatics, Norwegian University of Science and Technology
Høgskoleringen 7, 7491 Trondheim, NORWAY
E-mail: terjem@ntnu.no
Phone: +47 73 59 45 81
2Department of Geography, University of California at Santa Barbara
3611 Ellison Hall, Santa Barbara, CA 93106-4060, USA
E-mail: kclarke@geog.ucsb.edu
Phone: +1 805 893 3663
3 Department of Geography, University of Zürich
Winterthurerstr. 190 CH-8057 Zurich, SWITZERLAND
E-mail: sara@geo.unizh.ch
Phone: +41 44 635 51 50
Abstract. Methods for interactive map animations are still in an early stage
compared to more traditional cartography, and the potentials for improvements
are significant. This paper focuses on better design for map animations,
particularly for the portrayal of the information regarding the temporal
dimension. A series of animations are presented and discussed and
subsequently introduced to a wider group of people. In the responses from this
group it was not possible to show any significant difference in how well people
respond to the different animations, nevertheless people do have preferences for
certain animation types depending on which time-scale they represent.
Key words: Dynamic maps, interactive maps, visualization, map animations,
spatio-temporal information.
1. Introduction
People have used maps as tools for description of the geographical environment for
ages, while the media for transmission of geographic information have changed over
the years. Materials like stone, mammoth teeth, clay tablets, silk, papyrus, wood,
copper, paper etc have been involved. Today most maps are stored electronic, and
many of them are passed on to the user trough a computer screen. While cartography
has been concentrated on static illustrations during thousands of years, computer
based methods open for a new category of maps: the map animations and dynamic
maps. These maps offer something that never could be a part of the traditional maps;
45
movement and change in the map. However, the quantity of map animations has not
really increased that much until the last 10 years. And it is quite obvious that the
Internet and the World Wide Web (WWW) has been the most important catalyst for
this increase. Still most of the maps on the web remain static, but several high level
programming languages and applications for preparation of animations are now
making the production of animations easier. However, even though the technical
framework is becoming more accessible we still need more knowledge on how these
animations should appear.
Research has begun to examine how effective animations are for the
communication of information. Reviewing empirical animation research Tversky
(2002) found that many animations are too complex and too fast to be accurately
perceived. The necessity of making animation without too much detail was pointed
out by Harrower (2003). The information has to be well arranged and include as few
details as possible to be effective. Tversky (2002) also pointed out that animations
might generally be more effective when they are interactive, and she makes a sharp
distinction between non-interactive and interactive animations. Although
Tversky(2002) reviewed experimental work dealing with animations in general and
not map animations in particular, she found no advantage in using animations
compared to using a series of static pictures (Tversky, 2002). In the reviewed
experiments, the length of the time period for studying the figures/animation did not
seem to be a controlled variable.
Geographic space is central to all geographic information, yet almost all
geographical data are also highly structured in time. Like space, time has granularity
and extent. In geology and geomorphology, changes occur on a very long-term time-
scale, while in meteorology and traffic analysis, the dynamics are hour to hour and
minute to minute. Cartographic animation has emerged as an important tool for the
interpretation of time-space information (Peterson, 1995). Before the computer age
such animations were rare. The most famous early cartographic animation may be
Disney’s visualization of the German attack on Warsaw in 1939 (Peterson 1999).
Using movie technologies was rather expensive and time consuming, so there were
few examples in cartography until Tobler’s animation of the population growth of
Detroit (Tobler, 1969).
While most map animations focus on depicting spatial change using visual
variables (Bertin, 1981) as extended for dynamics (DiBiase et al., 1992), the design
aspects of temporal change have often been overlooked. Koussoulakou and Kraak
(1992) pointed out that the mapping of spatial data’s multi-dimensional and temporal
component would be an important challenge in the nineteen-nineties. During the last
decade we saw many examples of animations for this kind of data, but there remain
many unsolved research issues connected to the problem. Other than animations
involving changing the map viewing geometry for an unchanging map, most
phenomena that are visualized in an animation do have a strong temporal message. In
such presentations, time itself is an important variable that has to be included, and
clearly needs to be an easy perceivable component of the map. According to Bertin
(1981) only one variable, in addition to the position, should be presented on a
thematic map when the aim is to make a "seeing map", i.e. to keep the perception of
the contents on a global level. In many applications, on the web, it is indeed the only
variable shown on the map. However, on these maps time is symbolized as text, often
46 Proceedings, ScanGIS’2007
“hidden” on the fringe of the application. Slocum et al. (2000) state that it is difficult
to keep one’s focus on the main phenomenon in the animation and to read the text
outside the map simultaneously. One solution might be to use some kind of sound
(Midtbø, 2000), but this is restricted to sequential information, and is consequently
less suited for interactive animations. To keep the information visual we can use an
animation for the temporal component as well as for the main phenomenon. Kraak et
al. (1997) proposes the use of dynamic legends describing the passage of time. In an
experiment Edsall et al. (1997) depicted the passage of time as separate animated
legends, placed below the animated map. However, their results were inconclusive,
showing no significant differences in performance or speed among any of the legends.
In this paper we introduce some examples on animation where we attempt to
explore how visual variables can be applied to depict the passage of time jointly with
spatial change. According to Slocum et al. (2000), the temporal legend which has the
width of the map itself might be easier to interpret than a legend occupying a small
portion of the display window. In some of our examples the temporal legend has both
the width and the height of the animation and is, in one way, incorporated into the
map animation itself. The ideas for some of the presented animations were originally
introduced in Midtbø (2000).
2. Animation of time
This paper looks closer into how the presentation of “time” can be included in an
animation. This involves several problems to be addressed like such as; differences in
time scale (one hour, one decade etc.) and different techniques for the presentation of
time within these scales. Cross testing display combinations makes for a wide variety
of animations when the various methods are compared.
For the visualization of the temporal component it might be appropriate to
consider how people perceive time and how natural phenomena influence our
perception of time. Block (1990) outlined how humans perceive time. Three
important factors are succession, duration and temporal perspective. The length of
perceived episodes and the order of incidents are of importance. People also use
“tags” from various experiences as “temporal indexes” much as they use landmarks
during navigation. Natural phenomena, like the earth moving around its own axis and
the earth moving around the sun, pave the way for perception of time as a repeating
pattern. For such repeating temporal patterns it is reasonable to consider a circular
model for the temporal component rather than the more common linear model.
Multiple ways of representing the passage of time in map animations were
designed. Most were based on incorporation of the temporal component into the
animation itself. The “time legend” used in these methods encircles the map and is no
longer situated outside the animation. The intent was to use the peripheral vision of
the map interpreter to visualize the temporal component at the same time as the main
phenomenon is studied in the map animation. Care must be taken when deciding
which visual or dynamic variables to use. It is important that the variable used for
visualizing time differs from the variable used for the main phenomenon. In most of
our examples, dynamics in the thematic map animations are represented by changing
Midtbø, Clarke and Fabrikant 47
the size of circles on a representative proportional circle map. This means that the
visual variable “size” is used (Bertin, 1981), and also to some degree the dynamic
variable “rate of change” (DiBiase et al. 1992). Hence, these variables should be
avoided when visualizing time in the same animation. The list below shows an
overview of the animation types that were evaluated. The various animation types can
be studied at:
http://www.geomatikk.ntnu.no/prosjekt/tempvisual/Time_animation.html
xBackground shadow (Figure 1). In these animations the background of the map
changes as a shadow is moving from one end of the map to the other. Alongside
the map there is a time scale, which the shadow passes over. The darker area
(shadow) may move from left to right, right to left, from above to below or from
below to above the map. In our case the shadow moved from left to right behind
the map animation. It is also possible to use a circular movement of the shadow for
a cyclic visualization of the temporal component. Another type in the same
category is when the background of the animation initially is dark, and a lighter
background “slides” in to denote change in time. We also tried a highly transparent
shadow that slides in on top of the map animation. However, this type had less
positive effects on the visualization. By using a moving background shadow, it is
the visual variable position that represents time and the front of the moving shadow
that indicates the present point of time.
xAnalog clock hand (Figure 2). For temporal phenomena that have a circular
character it is possible to use a clock hand as time indicator. The aim is still to
incorporate the visualization of time in the animation, so the clock hand rotates
behind the map and points at a time scale that encircles the map. While this figure
illustrates a circular animation, it is also possible to use a pointer that moves along
a linear scale. The pointer indicates time in the same way as the front of the
shadow in our previous example. It seems appropriate to consider such an
animation for phenomena that are cyclical in a 24-hour period. However, an analog
Figure 1: Background shadow
48 Proceedings, ScanGIS’2007
clock animation will, by most people, be identified as a 12-hour cycle. The
background intensity can be used to distinguish between night and day in a 24-hour
period. We also considered some animations where the hand was on top of the
map, but this seemed less suitable.
xSatellite (Figure 3). Instead of the “clock hand” a satellite object is moved along
the time scale indicating the point of time. Since this is different from an analog
clock with hands, the method might be more appropriate when showing
phenomena with other cyclical time durations than 24-hours. Figure 3 shows
temperature changing over one year. Like the other animations this is interactive. It
is possible to start and stop the animation with the control panel, and the animation
can be run forward and backward continuously or step by step. In addition it is
possible to jump to a chosen time in the animation by clicking on the small
stationary and transparent satellites along the time scale. This “time jump function-
ality” seems particular useful. Finally it is possible to move the legend circles to
compare them with the growing and shrinking circles in the map on close range.
Figure 3: Satellite
Figure 2: Analog clock hand
Midtbø, Clarke and Fabrikant 49
xSun/moon icon (Figure 4). For a 24-hours period the satellite can be substituted
for a sun/moon icon. To point out the difference between night and day, the icon
changes from a moon to a sun at 06:00 in the morning, and back to a moon at
06:00 in the evening. An alternative type of this animation is shown in figure 4.
Here the animation is based on the fact that the sun rises and sets behind a horizon.
The sun icon is moving along a semicircle over the “map horizon” at daytime. At
“sunset” a moon icon starts in the same orbit. In addition to the alternating icons it
is possible to change the background intensity to emphasize the day/night
transition. The drawback of the method is that the time scale is no longer directly
compatible with an analog clock. Here a combination of the visual variables
position,form and intensity represents the temporal dimension.
xEmbedded hands (Figure 5). This time illustration depends on the visual variable
that is used to show the primary phenomenon. In our example we use proportional
Figure 4: Sun/moon icon
Figure 5: Embedded hands
50 Proceedings, ScanGIS’2007
circles. As we can see from Figure 5, a hand is embedded in each circle on the
map. All the hands are moving in parallel and their positions/angles denote the
point of time. This analog clock type animation depends on a circular
representation of the primary phenomenon. It is however possible to imagine hands
embedded in other symbol types. One problem with the method is that it might be
more difficult to comprehend the time information when the circles become very
small.
xGrowing bar (Figure 6). This is may be one of the few of our examples that can be
found in other applications. In Figure 6 the bar is growing along a time scale. The
bar is usually horizontal, but vertical variants could be considered. As Slocum et al.
(2000) suggests, our growing bar has the width of the map itself, and is not situated
in a peripheral position in the window. In the growing bar it is mainly the variable
Figure 6: Growing bar
Figure 7: Alternating pictures/icons
Midtbø, Clarke and Fabrikant 51
position that shows time, partly assisted by the variable size. Because of the
qualities of our peripheral vision it is important to give the bar an intensity that is
in contrast with the background.
xAlternating pictures/icons (Figure 7). In human perception of time information is
“stored” in the brain and “linked” through a kind of indexing. Much of this
indexing is individual, but to some degree common experience leads to a common
understanding. This fact is utilized in the moon/sun example. Most people connect
the sun icon with daytime and the moon icon with nighttime. Other icons can be
employed for groups that have common interests. Figure 7 shows an animation in
which different pictures of cars are used for time indexing. Each car represents a
certain decade. In this animation the car models and styles change as the cars move
along the time scale. Consequently, a combination of the variables position and
form are used to visualize the temporal dimension. In one of our animations the
changing cars only represented time (no change in position). Compared to the
animation from Figure 6 this animation, which was based on the variable form
only, seemed less interpretable.
xAlternating text (Figure 8). This represents the most commonly used method for
the representation of time in map animations on the Web today. The time is
indicated by dates, years and clock hours or similar, written as text and numbers.
These are often represented by too small a font and are situated too far outside the
animation. Their distinctness can be improved by increasing the font size, and by
moving the text closer to the animation.
xSliding map (Figure 9). In all the animations the presentation of time has a central
position, but in this type the temporal dimension is even more central. The time
scale is dominant in the display, and the map animation slides along the time scale.
The position of the map itself denotes the point of time. If the map reader is
studying a certain site on the map, this site can be connected to the time scale.
Unfortunately, the map has to be rather small in this animation to avoid inaccuracy
Figure 8: Alternating text
52 Proceedings, ScanGIS’2007
in the perception.
xTransparent/emphasized map (Figure 10). This animation permits more
Figure 9: Sliding Map
Figure 10: Transparent/emphasized map
Midtbø, Clarke and Fabrikant 53
interactivity than animation. As in the sliding map, the time scale is central. A
series of small mutliples are located along the time scale. Initially all the maps are
transparent. By moving the mouse pointer over a map it is highlighted by reducing
the transparency. The position of the map in the time scale supplies the temporal
information.
xMouse over legend (Figure 11). Here we use an active legend (Peterson 1999)
where the temporal change in the animation is controlled by moving the mouse
pointer along a time scale. In Figure 11 the time scale consists of years written as
text. Both the text itself and the position of the text represent the temporal variable.
3. Testing the animations
The animations presented in Section 2 is based on fundamental cartographic
theory, some triaal and errors and the autors subjective ideas for design. However,
would these animations be attractive and easy understandable for a wider group of
people? And which kind of animation would be best adapted to different time-spans?
Fore answering these questions an experimental web-interface was designed. More
details about this application can be studied in Midtbø et al. (200x).
Initially, many different animations were considered for exploration and testing.
For the final trial it was decided to concentrate on a subset of the characteristics of
time animation. A principal conceptual difference among the methods outlined above
is their treatment of time as a circular variable, a linear variable, or a simple text
string. The various tests in the application was designed and organized to explore
different aspects of the animation of time. First, they were intended to investigate
whether this basic division of the animations was reflected in peoples’ perceptions.
Secondly, the tests focused on whether any of the animation types were better suited
for particular time periods. Accordingly, for each animation type (circular, linear and
Figure 11: Mouse over legend
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text) we introduced four different time spans: a 24-hour period, 12 days, 1 year, and 4
decades. The conterminous United States (excluding Alaska and Hawaii) was used as
the geographical extent for the experiment. For the animations’ primary phenomenon,
various kinds of weather information were used for time spans up to 1 year, and
population growth was used for variations over decades. Table 1 shows the data sets
together with their corresponding time periods. All the variables were represented
similarly, by proportional symbols, using growing and shrinking circles. For each
phenomenon three different data sets were prepared, each based on information about
weather and population in seven cities situated around the country (Figure 12).
Table 1: Time spans and corresponding phenomena
Figure 12: The Three Distributions of Cities
Each of the animations presented above were implemented in Macromedia
Director to contain an interactive control panel. This included “move forward”,
“move backwards”, “stop”, “step forward” and “step backwards” buttons. It was also
possible to jump in the animations by clicking on the markers along the time-scale.
This detail made the repeated study of a certain time-period efficient. Finally, to get a
better comprehension of the size of the proportional circles in the animation, it was
possible to move the transparent circles from the legend into the animation itself. In
order to make the recording process of the interaction simpler and easier to investigate
user reaction to the animations, this control panel was simplified for the versions
presented on the web. All buttons were made inactive except the start button. In
addition a button to terminate the animation was introduced. This made it possible to
Time span Primary
phenomenon
Temporal
resolution
Visual
variable
Dynamic
variable
24-hours Wind speed (I.e.) 1 hour Size Display date,
rate of change
12 days Temperature above
and below normal
temperature (F°)
24 hours Size, color
(above-red,
below-blue)
Display date,
rate of change
1 year Temperature above
and below normal
temperature (F°)
1 month Size, color
(above-red,
below-blue)
Display date,
rate of change
4 decades Population growth (%) 10 years Size, color
(growth-
b
lue,
reduction-red)
Display date,
rate of change
Midtbø, Clarke and Fabrikant 55
measure how long the animation was viewed by the users. On the other hand, this
excluded most kinds of interaction when the animation was running.
For each animation in the experiment a question was asked before the user got
access to the animation. The user was asked to study two particular cities on the map
animation. The question was accompanied by a figure that pointed out the two cities.
Figure 13 shows an example how the questions were asked. Next, the animation was
started and the viewer was asked to terminate the animation as soon as he/she knew
the answer to the question. Finally, the audience had to answer the question by
choosing between alternatives. Table 2 shows the alternatives for the different time
periods.
Table 2: Alteratives in the questionnaire
Time span No. of alt. Alternatives
24 hours 8 6pm-9pm, 9pm-12am, 12am-3am, 3am-6am,
6am- 9am, 9am-12pm,12pm-3pm, 3pm-6pm
12 days 4 5-7, 8-10, 11-13, 14-16 (dates)
1 year 4 Jan.-Mar., Apr.-Jun., Jul.-Sep., Oct.-Dec.
4 decades 4 1960-1970, 1970-1980, 1980-1990, 1990-2000
Figure 12: Questions asked before the animation
56 Proceedings, ScanGIS’2007
4. Accomplishments and results
The application for testing the animation on a larger group of people was
announced on some major cartography interests discussion lists in USA. After some
weeks we had received 133 answers, most of them during the first week after the
announcement. Forty-five of these were women, and 101 out of 133 claimed to have a
formal education within Cartography (not a surprise considering the mailing lists for
announcement of the experiment).
In the questionnaires the participants were asked to check off the time periods that
they believed reflected the data shown in the animations. The results from the
questionnaires were quite varied, so initially we studied the time each participant
spent watching the animation before he/she terminated it to answer the questions.
Some answers were rejected due to slow computers on the client side, some
evident misunderstandings etc., leaving 91 subjects. The mean value for the measured
time the participants used before answering the questions showed a marginal
difference between the three animation types. Most variation appeared for the 4
decades time span, which was presumed to be the animation with the easiest time
representation. The results showed a mean value of 12 seconds for the linear
animation, 10.3 seconds for the circular animation and 13.1 second for the text
animation. However, since the standard deviations are respectively 9.4, 6.8 and 8.1
the analysis of variance showed no significant difference between the animation
types.
After the participants had completed the four animations, examples of the two
remaining animation types were introduced. They were then asked some questions
about which type of animation they preferred for the various time spans. The results
from these questions are shown in Table 3. There are clear preferences for some of
the animation types in combination with particular time spans. The majority of the
participants preferred the circular animations for the visualization of a 24-hour period,
while the linear animations seem to be most attractive for time spans of a non-cyclic
character. About 60% of all the participants prefer the linear animation for the 12 days
and the 4 decades periods. One year is a common period related to a natural
phenomenon. However, from the table we can see that the group that prefer a linear
animation is about the same size as the “circular group.”
Table 3: Preferred animation types
24 hours Year 12 days 4 decades
Prefer linear animation 23.3% 45.1% 57.2% 61.7%
Prefer circular animation 68.4% 45.9% 29.3% 24.8%
Prefer textual animation 8.3% 9.0% 13.5% 13.5%
Midtbø, Clarke and Fabrikant 57
Table 4: Preferred animationtypes dependent on employed animation in the experiment
24 hours Year 12 days 4 decades
Linear animation in experiment
Prefer linear animation 29.8% 53.2% 68.1% 74.5%
Prefer circular animation 66% 44.7% 21.3% 17.0%
Prefer textual animation 4.2% 2.1% 10.6% 8.5%
Circular animation in experiment
Prefer linear animation 32.6% 45.7% 56.5% 60.9%
Prefer circular animation 63.0% 50% 34.8% 32.6%
Prefer textual animation 4.3% 4.3% 8.7% 6.5%
Textual animation in experiment
Prefer linear animation 8.7% 34.7% 43.5% 47.8%
Prefer circular animation 76.1% 45.7% 34.8% 28.3%
Prefer textual animation 15.2% 19.6% 21.7% 23.9%
In Table 3 the preferences for all the participants are included, independent of
which type of animation they were assigned during the experiment. However, we are
actually looking at three different groups of participants; a group that used the circular
animations, another that used the linear animations and a third that used the textual
description during the experiment. Were the preferences of the participants in the
different groups influenced by the animation used in the experiment? Table 4 shows
the preference for animation types based on which type of animation that was
employed during the experiment.
If we compare the average results in Table 3 with the numbers in Table 4 there is a
tendency for participants to favour the animation type to which they were exposed
during the experiment. There is only one exception from this tendency; for the
participants in the “linear group” the preference for a circular animation for a 24-hour
period is greater than average. Correspondingly their preference is lower than average
in the “circular group”.
5. Conclusions
It is our belief that map animations of today have significant potentials for
improvements. In this paper we have presented some methods for the portrayal of the
passage of time, and tested some of these on an audience. The practical case in the
experiment is focused on people’s reaction to various animations representing time.
We measured the time each participant studied the animations before he/she was
prepared to answer a series of questions. The results gave no significant indications
that one of the animation types in the experiment was better suited for temporal
representation. This could be a negative result, or it could indicate that different
people have different personal preferences. However, the answers to the questions
were quite scattered, and made it difficult to make any conclusions. By studying the
data we can see that the questions related to the animations were too ambitious for
58 Proceedings, ScanGIS’2007
this type of experiment. To discover the usefulness of the various temporal
representations in web-based experiments it is necessary to prepare simpler and more
unambiguous tasks.
On the other hand there was a distinct difference in which type of animation the
participants preferred. For the representation of a period of non-cyclic nature, most of
the participants preferred a linear animation for the representation of time. For the
natural cyclic period of a year, the preference was about even between the circular
animation and the linear animation, while most participants preferred a circular
animation for a 24-hour period. It was also evident that most of the participants
preferred a figurative animation above representing time by changing text.
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60 Proceedings, ScanGIS’2007
