From digital map to digital tactile map: a transmission with accent in
haptic language
Papadopoulos Konstantinos1 and Karanikolas Nikolaos2
Konstantinos S. Papadopoulos, Assistant Professor, Department of Educational and Social Policy,
University of Macedonia, 156 Egnatia st. P.O. Box 1591, 54006, Thessaloniki, Greece, [email protected]
Nikolaos Karanikolas, Visiting Lecturer, School of Urban-Regional Planning and Development, Aristotle
University of Thessaloniki, Raidestou 11, 546 636, Thessaloniki, Greece, [email protected]
Keywords: spatial knowledge, haptic perception, digital cartography, tactile maps.
Abstract
People with visual impairment are unable to collect the external visual stimuli from the environment or to
use conventional maps. So, the importance of tactile maps as informational and orientation means is
undoubted. The blind user perceives the information graphed on the tactile map by feeling the elements of
the map with the fingertips. There has been considerable research into the design of these maps over
recent decades, providing answers to most of the questions which have arisen concerning their
intelligibility – the use of symbols, for example, and the implementation of uniform standards to make the
maps generally accessible. For the production of tactile maps a number of methods have been developed
worldwide. The introduction of new technologies has contributed to the design and production of tactile
maps, following procedures appropriate to the special needs of tactile mapping, with automatic
cartography. During the procedure of implementing a tactile map with the use of a personal computer, a
basic stage is the construction of a digital map. In this paper, the design of tactile maps of Thessaloniki
(the second largest city in Greece) is discussed, with special emphasis in a number of relevant issues
influencing the whole process.
Introduction
Various factors affect an individual’s spatial knowledge including the characteristics of the
environment (size, structure, and familiarity), personal characteristics (age, cognitive
development, and perceptual modality for coding spatial information), and learning processes
(strategies for acquiring information, learning conditions, and medium for communicating
spatial information) (Espinosa & Ochaνta, 1998). Taking into consideration the nature of the
input of spatial information through the remaining perceptual systems of persons who are blind,
it is important to study the effects of different instructional methods for teaching people who are
blind about space (Espinosa & Ochaνta, 1998).
The majority of people have used a map to collect information, locate the spatial position of
certain information, orientate, plan journeys, map out routes, calculate distances between places,
and help themselves become familiar with a region. People with visual impairment are unable to
collect the external visual stimuli from the environment or to use conventional maps. So, the
importance of tactile aids (tactile models and tactile maps) as tools providing spatial information
and orientation is undoubted (Papadopoulos, Livieratos and Boutoura 2001, Papadopoulos
2004). The usefulness of tactile maps for teaching people who are blind about space has been
demonstrated in several studies (Espinosa & Ochaνta, 1998). A tactile map provides a view of a
novel environment that can stand in, to some extent, for a visual view of the environment
(Golledge, 1991).
Tactile maps are raised-line images which are used to convey information in graphic formats to
visually impaired people (blind or individuals with low vision). This information can be of great
importance as it allows visually impaired people to study, work, and live more independently
(Jehoel, Ungar, McCallum & Rowell, 2005).
The spatial layout of the represented area can perceived with a tactile map, without conducting
any distracting navigational activities, such as avoiding obstacles (Harder & Michel, 2002).
Visually impaired people who read and memorize a tactile map in order to prepare themselves
for traveling an unfamiliar route in an unknown environment, travel more safely and efficiently
through that route than do those who either use an audiotaped description or travel the route
accompanied and advised by a sighted observer (Espinosa, Ungar, Ochaνta, Blades, & Spencer,
1998).
In Espinosa and Ochaνta (1998) study, the effects of three instructional methods direct experience, cartographic representation, and verbal description - on the spatial
knowledge of 30 adults who were blind, were estimated. According to the results
participants' practical spatial knowledge was better when they learned the route with a
tactile map than in either of the two other conditions.
Tactile maps can provide visually impaired people with knowledge about both proximate and
distant places and contribute to successful wayfinding (Ungar, Blades & Spencer, 1996). Usage
of a tactile map with the intention to find a way requires certain skills, such as: the ability to
read the map effectively, to orient the map, and to extract appropriate information (e.g. distance
and direction of landmarks in the environment) from the map. Moreover, users have to be able
to locate themselves on the map and then update their own position as they move through the
environment (Ungar, Blades & Spencer, 1996). Studies that have considered tactile maps as
wayfinding aids are few and have concentrated on adult map users, while the limited research
on children's use of tactile maps for wayfinding and navigation has shown that even young
children can use simple tactile maps to work out the direction of nearby places (Ungar, Blades
& Spencer, 1996).
Visually impaired users can gain information about the spatial relationships between places
much more rapidly from a tactile map than from direct experience with the environment if they
understand scale and can translate distances on a map into distances in the environment (Ungar,
Blades, Spencer, & Morsley, 1994). Visually impaired children can be taught how to calculate
distances from a map, and this ability can contribute both to their understanding of maps and
their mobility skills (Ungar, Blades & Spencer, 1997).
Of equal importance is the contribution of tactile maps in formatting new cognitive maps or in
reforming the existing ones (Papadopoulos, 2004). The ability of visually impaired individuals
of different ages, and especially children, to construct cognitive maps is a subject which has
stimulated much interest in the scientific community (Spencer, Morsley, Ungar, Pike & Blades,
1992; Landau, Spelke & Gleitman, 1984). According to Harder & Michel (2002), anyone who
reads a tactile map by successively touching parts of the map will have to build up a mental
spatial structure of the represented area (Rèvèsz, 1938, cited in Harder & Michel, 2002).
The use of tactile maps leads to the issue of which strategies should be used to explore tactile
maps. This issue has been addressed in several studies, all of which have stressed that
systematic exploration procedures yield better results (Espinosa & Ochaνta, 1998).
Haptic perception
Blind individuals can use perceptual cues (auditory, tactile, kinesthetic, and olfactory) in order
to pick up, codify, store, and recover spatial information (Espinosa & Ochaνta, 1998). Using the
above alternative strategies, blind individuals can move about and gain efficient knowledge of
space. Thereby, they can organize spatial information in a functionally equivalent way to
sighted individuals. However, given the characteristics of perceptual systems other than vision,
this task is more time consuming and more cognitive effort assuming for blind people than for
sighted people (Espinosa & Ochaνta, 1998).
The blind user perceives the information graphed on the map by feeling the elements of the map
with the fingertips. For the education of visually impaired people and for their space
comprehension, ‘touch’ is considered as basic modality for selecting information.
Recognition through touch is not direct, as in the case with sight. First, we see the whole, and
then we observe its parts. However, in the sense of touch, the construction of the whole is a
mental process that takes place after the perception of the parts (Revesz 1950). Several writers,
Piaget among them, have noted that the development in haptic exploratory characteristics is
similar to that in visual exploration, with haptic development following a timetable that is
comparatively delayed. Much of this delay may be related to the characteristics of the receptors
for the two modalities (Piaget 1953). Two important differences are obvious (Warren 1982):
The first is related with incapability of hands comparing them with eye movements. Hand and
its fingers are more cumbersome than the eye, making explicit that visual system is better and
earlier prepared to make the fine muscular adjustments needed for regular and rapid exploration
of stimuli. Second difference related with spatial distribution of receptors in the eye - that is
more conducive than that on the hand to the simultaneous registry of spatially distributed
stimulus arrays. Peripheral field of vision allows the synchronised import of spatial
relationships, in contradiction with the attribute of ‘sequence of actions’, that is characteristic
for haptic exploration.
Unlike a print map, from which spatial and other information can be read off almost
simultaneously, a tactile map must be explored sequentially. There are two important
consequences of this. Firstly, acquiring spatial information from a tactile map may place greater
demands on memory, as the information will have to be integrated from successive hand
movements. Secondly, it is likely that different tactile scanning strategies will be differentially
effective for gathering the relevant spatial information (Ungar, Blades and Spencer 1993).
Strategies that are in use during the haptic exploration, affect strongly the haptic perception
(Warren 1982). There are research results (Abravanel 1968, 1973, Davidson 1972a, Berla and
Butterfield 1977) supporting this opinion. However, a number of studies have demonstrated
significant improvement in haptic performance with experience (Davidson 1972b, Simmons and
Locher 1979, Davidson, Appelle and Pezzmenti 1981). Ungar, Blades and Spencer (1993) noted
that visually impaired children could remember and reproduce the array of tactile map symbols.
Therefore, the additional use of memory involved in employing a tactile map would not put
visually impaired children at any particular disadvantage.
Many persons who are visually impaired have difficulty accomplishing the task of reading the
tactile map (Ungar, Blades, & Spencer, 1995, 1996, cited in Harder & Michel, 2002). In
general, visually impaired people read a tactile map slower and understand it less than do
sighted people who see a visual print of the same map (Ungar et al., 1995, cited in Harder &
Michel, 2002). However, blind children improved their ability to orient themselves (Ungar et
al., 1997, cited in Harder & Michel, 2002) or to locate certain distinctive features on a tactile
map (Berla & Butterfield, 1977, cited in Harder & Michel, 2002) after a fewer than 10 hours
systematic training of appropriate tactile scanning strategies (Ungar et al., 1997, cited in Harder
& Michel, 2002). In any case, additional research is necessary to analyze in detail the strategies
used by proficient - in the exploration of tactile maps - blind people and then to train
inexperienced blind people in the use of these strategies (Espinosa & Ochaνta, 1998).
Haptic variables
The optical variables of Cartography, shape, orientation, texture, color hue, size and color value
(Bertin, 1977) are used in the conventional science of map-making for the presentation of
qualitative and quantitative information (Papadopoulos, Tsioukas & Daniil, 2003).
In case of tactile maps there are some differentiations with regard to Bertin’s optical variables.
Color hue variable is not used when the map is read by totally blind individuals, while rise
variable (height off the base surface) fills in the rest 5 variables, which are texture, shape,
orientation, size and color value. “Rise” variable can be used only where the map-printing
method admit it. Thermoform method is such a method. On the other hand, in microcapsule
maps this variable is not used. The haptic variables are shown in Figure 1 (Papadopoulos, 2000).
Differences to “shape” variable as well as to “size” and “rise” variables are easier discriminated
by haptic readers (Papadopoulos, 2000). Thus, two haptic symbols which differ toward one of
those variables are easier discriminated by the user as different without confusion.
However, for ease discrimination of haptic symbols it is necessary to differ to more than one
haptic variables. For example, it is easier to discriminate two symbols with different size and
shape than two symbols which differ only to the shape, especially if the symbols are small.
According to Bentzen (1996) the choice of tactile maps symbols should be based on two
considerations: 1. symbols should differ between them in as many ways as possible in order to
be maximally discriminable, and 2. symbols should be easy to associate with the features they
represent. Preiser (1985) recommended two braille cell labels as the most memorable instead of
all other types of point symbols for highly schematic tactile maps. James and Gill (1974), as
well as Lambert and Lederman (1989) found that meaningful symbols are particularly quickly
recognized and accurately identified.
Figure 1. Haptic variables: shape, size, texture, value, orientation and rise which are used for
the presentation of tactile symbols (Papadopoulos, 2000).
The production of tactile maps
The importance of tactile maps means first that they should be accessible to the visually
impaired, and second that they should be correctly interpreted. There has been considerable
research into the design of these maps over recent decades, providing answers to most of the
questions which have arisen concerning their intelligibility – the use of symbols, for example,
and the implementation of uniform standards to make the maps generally accessible
(Papadopoulos 2005).
A number of methods have been developed worldwide for the production of tactile maps (see,
e.g., Turner, & Sherman, 1986; Dacen-Nagel & Coulson, 1990; Edman 1992; Papadopoulos
2000). Tactile maps and tactile graphics in general are produced using various substrates
(background materials), based on the production method that is used every time (Horsfall 1997).
For example, the stereo-copying process uses microcapsule paper that contains heat-activated
microcapsules, embossed graphics are produced using paper, thermoform uses thermoplastic
polymers, and screen-printing is done on a wax-based paper (Jehoel, Ungar, McCallum &
Rowell, 2005). A new technology, the TIMP tactile inkjet printer, can print tactile images in
polymer on a large variety of substrates. This printer uses a 500-nozzle, 180 dots-per-inch,
piezo, drop-on-demand industrial printhead. Ultraviolet cured ink drops of 80 picoliters are built
up in a multilayer process (see McCallum & Ungar, 2003).
Previous studies have attempted to measure differences in map-reading performance for maps
produced in various methods. Dacen-Nagel and Coulson (1990) studied map-reading
performance on maps of several levels of complexity that were produced by four methods.
According to their study, microcapsule maps received the most favorable comments, followed
by multitextural maps and maps that were produced by letterpress plates, whilst thermoform
maps received the most unfavorable comments. On the other hand, Pike, Blades and Spencer
(1992) found that there are no significant differences in map-reading performance of visually
impaired children using microcapsule and thermoform maps.
In their study Jehoel et al. (2005) evaluated the relative suitability of different base materials for
the production of tactile maps and diagrams via a new ink-jet process. During this study visually
impaired and sighted participants performed a search task on seven substrates. Specifically, they
ranked the substrates on the basis of their individual preferences with regard to their search
time. In general, the participants explored plastic and aluminum substrates slower than they did
paper substrates. According to this study results, paper substrates (particularly rough paper and
microcapsule paper) seem to be the most suitable for the production of tactile maps and
diagrams using an inkjet printing method. However, some other factors should be taken into
consideration as well. First of all, the selection of a substrate depends on the functions of the
map or diagram. For example, durable substrates, such as plastic and aluminum, are more
suitable for use in public places, whereas paper substrates (lightweight and easily folded up) can
more easily be carried by an individual user (Jehoel et al., 2005).
The introduction of new technologies, mainly in the last ten years, has contributed to the design
and production of tactile maps, following procedures appropriate to the special needs of tactile
mapping, with automatic cartography (Papadopoulos 2005b). During the procedure of
implementing a tactile map with the use of a personal computer, a basic stage is the construction
of a digital map. However, it is well known today, especially to those involved with
cartography, that many digital maps are available as a result of the creation of conventional
maps. Based on this heritage we can create easier tactile maps, avoiding the task of digitising a
map and concentrating on the generalization of graphical forms and on the writing of the braille
labels. Taking into consideration the above situation, we can say that the procedure for the
construction of the digital map includes the following stages (Papadopoulos 2000,
Papadopoulos, Livieratos & Boutoura 2001):
•
•
•
•
•
the construction of the geometrical content of the digital map;
the generalisation of the graphic forms;
the choice of tactile symbols, their construction and placement;
the placement of labels in braille;
the construction of a proper legend.
The generalisation process is more necessary when the development of a digital tactile map is
based upon a digital map for the visually people. Then is possible that an amount of information
must be generalized to be more comprehensible in accordance with the scale of the two different
maps.
For the placement of braille labels in digital map, some braille fonts are used. These braille fonts
come from the country where the map is constructed. However, citizens of other countries will
transcribe tactile maps in order to be readable. For the conversion of this braille labels into
English braille code, the transcription of braille labels is required. For decades now there has
been considerable discussion of – and research into – the transcription of conventional maps;
various ‘romanisation’ systems are now widely accepted and used. In Greece, designed a tool
for the automated transcription of Greek tactile maps into the Roman alphabet. That can be also
used for the conversion of Greek tactile maps into English braille (Papadopoulos 2005a).
Tactile city maps of Thessaloniki
This specific guide has been constructed in order to provide visually impaired people with the
necessary information for their orientation and mobility in the centre of Thessaloniki. The
choice of the area to be represented was based on a research about which areas of the city
considered to be useful and popular destinations for the visually impaired. The size of the area
thus covered was approximately 3700x2000 m.
For the development of the digital base-maps of tactile guide an existing map was used
(Livieratos, Boutoura & Myridis, 1997). This is a digital map for visually able people that was
processed and converted in a proper digital form for the construction of the tactile guide. All the
cartographic process was carried out using the MicroStation software. The generalisation
process was necessary for the transition from the conventional digital map to the “tactile digital
map”. Αn amount of information must be generalized to be more comprehensible in accordance
with the scale of the maps and taking into consideration the restrictions that the haptic mapreading puts. Specifically, in the conventional digital map the building squares, traffic islands,
all names of streets and squares, names of areas, pedestrian zones, galleries, and detailed
coastline, are presented thoroughly. In addition, all buildings of the mapped area, thematic
information which corresponds to specific “important buildings, and other important
information which corresponds to places, were presented as well. On the other hand, in the
“tactile digital map” a continuous thick straight line symbolize basic streets, a continuous thin
straight line symbolize the rest of the streets, and a straight dot line symbolize pedestrian zones
or galleries. In addition, buildings are not mapped, while coastline and traffic islands are
generalized. Furthermore, important information, street and square names are written with
braille characters (letters and numbers).
Braille characters have standard size (they are sufficiently bigger than the conventional
characters that an individual with normal vision is able to read visually) and there should not be
overlaps among braille labels in order to be readable. These two basic restrictions frequently
disable the presentation of whole braille labels and necessitate the use of abbreviations. The
practice of use braille numbers is a really efficient technique. This technique is also used in the
tactile guide of the present work. However, as a result of standard braille size and the number
sign, which adds one more character (for example number 4, for sighted individuals is written
using one character, whereas in braille is written using two characters, number sign and letter
D), the size of braille numbers is considerable.
The guide consists of two parts. The first part comprises pages printed in a braille printer, while
the second part consists of seven tactile maps (tactile Atlas) which have been printed on
microcapsule paper. Specifically, the tactile guide consists of:
•
•
•
•
•
Instructions for the correct use (part 1)
A legend of the names of the streets (part 1)
A legend of the information illustrated in the tactile maps (part 1)
1 guide map of the area under cartographic consideration (part 2)
6 detailed maps of the area (part 2)
In the first part, except for the instructions, the names of the streets and the legend with
information that is included in tactile maps of the second part, appear as well. Specifically, the
first part consists of the following sections: instructions for the use of the help guide, streets
names of the guide map, important information of the guide map, streets names of the detailed
maps, important information of the detailed maps, names of squares of the detailed maps.
The second part consists of a guide map for the whole mapping area, which appears first in the
maps’ sequence, and of six detailed maps of the area. The above maps have some areas in
common, so that the user could easily continue reading from the one detailed map to the other
(it’s adjacent).
In the guide map (figure 2), only some basic streets and their names as well as some important
information are presented. In the centre of the upper part of the map, the title of the map is
recorded. In the upper left edge of the guide map, illustrations of the used symbols are shown
(map-key). Particularly, a straight continuous line is used to symbolize streets, while a circle
plots the place where important information appears and a surface made of small dots stands for
the sea. In the upper right edge of the guide map, north direction (with an arrow) and the scale
of the map (graphic scale) is presented. On the map every street name appears as a number
which corresponds to its name. These numbers are not written in a beeline. On the contrary,
they follow every time the direction of the street’s line. The position of any important
information appears as a circle and next to it there is a braille label which consists of letter “i”
and a number. In order to find in which names the numbers corresponds, user should go back to
the parts of the legend where the streets names of the guide map and important information are
recorded. The scale of guide map is 1:9500. The tactile symbols that we used are shown in
figure 4.
The detailed maps (see for example figure 3) have common areas (overlapping) and the scale is
1:2400. In the centre of the upper part of each detailed map its title is recorded. The title of the
map consists of the number of the map (e.g. map 2) and a name representative of the mapping
area. In the upper right edge of the first map (map 1) illustrations of the used symbols are
shown. Specifically, a continuous thick straight line is used to symbolize basic streets while a
continuous thin straight line is used to symbolize the rest of the streets, and a straight dot line is
used to symbolize pedestrian zones or galleries. Furthermore, a small circle is used to show the
position of basic information, a surface made of small dots stands for the sea, a rectangle is used
to show where the buses starting points are and the printed form of letter “x” is used to show the
position of taxi stands. The tactile symbols that we used are shown in figure 4.
In the upper left edge of the first map, north direction (with an arrow) and the map scale
(graphic scale) is presented. Map scale as well as north direction is the same for all the detailed
maps. In each detailed map, each street name appears as a number which corresponds to its
name. These numbers are not written in a beeline. On the contrary, they follow every time the
direction of the street’s line. The position of any important information appears as a circle and
next to it there is a braille label which consists of letter “i” and a number. Finally, the position of
each square appears in a braille label which consists of letter “s” and a number. In order to find
in which names the numbers corresponds, user should go back to the parts of the legend where
the streets names, important information, and squares of the detailed maps are recorded.
The important information of the detailed maps is separated in categories and any information is
placed in the respective category. Specifically, there are the following 9 categories: 1.
antiquities, monuments, 2. museums, libraries, art halls, archives, galleries, 3. public services,
police, hospitals, 4. info centers, 5. theatres, cinemas, 6. universities, 7. halls (conferences,
exhibitions, culture), 8. sports, and 9. other familiar locations.
The guide map as well as the detailed maps were printed in A3 format (42x29,7 cm). Tactile
maps, the legends of the information illustrated in the maps, and the instructions for the correct
use, were printed both in Greek and English language.
Figure 2. The guide map.
Figure 3. One of the six detailed maps.
Figure 4. The tactile symbols that we used.
Acknowledgements. The tactile maps described in this paper were constructed in the
framework of the project ASK-IT (Ambient Intelligent System of Agent for Knowledge based
and Integrated Services for Mobility Impaired users). This is a 4-year Integrated Project, started
at the end of 2004. EC co-funded with 50 partners, budget of ap. 16 ME. It aims to develop an
ambient intelligence environment for the integration of functions and services for mobility
impaired users, enabling the provision of personalized, self-configurable, intuitive and contextrelated applications and services, while on the move.
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