DESCRIBING A THEMATIC MAP
by
Alecia Fowler
A thesis submitted in conformity with the requirements
for the degree of Masters of Science
Graduate Department of Computer Science
University of Toronto
© Copyright by Alecia Fowler 2010
Describing a Thematic Map
Alecia Fowler
Masters of Science
Graduate Department of Computer Science
University of Toronto
2010
Abstract
« Abstract text goes here. Maximum 300 words for doctoral or 150 words for master’s thesis
excluding title. Do not include graphs, charts, tables, or illustrations in the abstract.
Uses style “Abstract text” (double spaced). »
ii
Acknowledgments
« Use Body Text or Normal style for text in this section. »
iii
Table of Contents
Acknowledgments.......................................................................................................................... iii
Table of Contents ........................................................................................................................... iv
List of Tables ................................................................................................................................. vi
List of Figures ............................................................................................................................... vii
1 Introduction ................................................................................................................................ 1
2 Background ................................................................................................................................ 3
2.1 Web Mapping Accessibility ................................................................................................ 3
2.2 Thematic Maps and Accessibility ....................................................................................... 3
2.3 Cognitive Mapping ............................................................................................................. 5
2.4 Related Work ...................................................................................................................... 5
2.5 Conclusion ......................................................................... Error! Bookmark not defined.
3 Method ....................................................................................................................................... 9
3.1 Study Design and Execution ............................................................................................... 9
3.1.1
Early Iterations ........................................................................................................ 9
3.1.2
Web Application ................................................................................................... 10
3.1.3
Survey ................................................................................................................... 10
3.1.4
Map Descriptions .................................................................................................. 10
4 Results ...................................................................................................................................... 14
4.1 Analysis............................................................................................................................. 14
4.2 Description Techniques .................................................................................................... 16
4.3 Implicit vs. Explicit Data .................................................................................................. 17
4.4 The Effect of Scale Level ................................................................................................. 18
4.5 The Effect of Jurisdiction.................................................................................................. 20
4.6 The Effect of Missing Map Data ...................................................................................... 21
iv
4.7 The Context of the Keywords ........................................................................................... 23
4.8 Participant Results ............................................................................................................ 24
4.9 Threats to Validity ............................................................................................................ 27
4.9.1
Participant Background and Location ................................................................... 27
4.9.2
Thematic Data ....................................................................................................... 27
4.9.3
Missing Data ......................................................................................................... 27
4.9.4
Categorization of Data .......................................................................................... 28
4.10 Forming Map Descriptions ............................................................................................... 28
5 Future Research ........................................................................................................................ 31
6 Conclusion................................................................................................................................ 33
7 Appendices ............................................................................................................................... 34
7.1 Thematic Maps.................................................................................................................. 34
7.2 Survey ............................................................................................................................... 35
7.3 Definitions......................................................................................................................... 37
7.3.1
Thematic Maps...................................................................................................... 37
7.3.2
Web Accessibility ................................................................................................. 37
7.3.3
Web Mapping........................................................................................................ 37
Bibliography ................................................................................................................................. 38
v
List of Tables
Table 1: Classes of contextual information used by sighted and visually impaired participants ... 6
Table 2: Concerning the quality of the notes, the study found that out of 129 notes: .................... 8
Table 3: Thematic Map Description Categories ........................................................................... 14
Table 4: Category Ranking by Scale Level .................................................................................. 19
Table 5: Category Ranking by Jurisdiction .................................................................................. 20
Table 6: Top ranking words per category ..................................................................................... 23
Table 7: Participants By Age ........................................................................................................ 24
Table 8: Participants by Field ....................................................................................................... 25
Table 9: Category Rankings by Field-Related Experts................................................................. 26
vi
List of Figures
Figure 1: Screenshot of Web Application ..................................................................................... 12
Figure 2: Sample map of large scale ............................................................................................. 19
Figure 3: Sample map of small scale ............................................................................................ 20
Figure 4: Sample map of urban jurisdiction ................................................................................. 21
Figure 5: Sample map of rural jurisdiction ................................................................................... 21
Figure 6: Distinct Keywords by Category .................................................................................... 23
Figure 7: Participant Level of Expertise in Study-Related Fields ................................................ 26
Figure 8: Map Sample ................................................................................................................... 29
vii
1
1
Introduction
Web mapping applications are a popular way of interacting with maps sets online as they provide
an effective mode for interactivity, customization, and transportability [15]. The information is
communicated in a primarily visual way, which causes the web page to be inaccessible to a
visually impaired audience. This study addresses the need for accessibility solutions in the area
of web mapping. When following web accessibility standards for producing online content, a
text alternative is needed for every non-text element on a web page. In order to address this, a
long text description needs to be offered as an alternative to the map, as a map is so rich in data a
short text description will not suffice.
People with visual impairment have the ability to understand and make use of spatial concepts
[18]. There has been an abundance of research done on meaningful context-based descriptions
when addressing directional maps and wayfinding [9][25][4][3]. However, when looking at
thematic maps, an area of mapping where spatial distribution and relationships are of great
importance, it is unknown how to create a meaningful text description. A meaningful text
description would be any description that provides the equivalent amount of information that is
delivered visually and delivered in a usable way. Data in a tabular format is often treated as an
equivalent alternative, due to it’s text-based format [16], but we will argue that this is neither
equivalent or meaningful to a user, as the understanding a person takes from viewing a map is
comprised of much more meaning that is not available in the data used to create the map, this we
term as the implicit data.
Meeting accessibility standards in the area of web mapping is important as we believe it will
provide impaired users with a richer, more usable experience. It is a web developer’s ethical
duty to provide content in the most accessible way possible as every user has the right to view
content online [22] without having to purchase additional costly assistive devices. Through
satisfying the accessibility guidelines and designing web mapping applications to on the most
basic device first then enhancing the experience gradually, these issues may be resolved.
In order to formulate a meaningful text description of a thematic map we conducted a study
which required participants to describe various maps. The descriptions were then subjectively
2
analyzed in order to construct a framework on which to base the creation of a meaningful long
text description on. We present our findings in the following chapters.
3
2
Background
In this chapter we relay the current situation the area of web mapping is facing in regards to web
accessibility. We then describe the areas this thesis will focus on and why. Finally, we review
important literature related to the topic of this paper and how is has helped to understand the
area.
2.1 Web Mapping Accessibility
Web accessibility refers to the way in which the World Wide Web and its content can be used by
all people, regardless of any physical, cognitive, sensory or developmental impediment.
Websites and web applications should be designed with these impediments in mind, and cater to
the tools that are available to assist in the delivery of the site and its applications. As the web
continues to grow it is easy for software developers to forget about accessibility guidelines if the
standards do not clearly address the type of content they are developing.
Web Mapping Accessibility faces such a situation. Web Mapping includes all types of maps that
are placed online for use in both a static or dynamic format. There are no clear guidelines on
how to make maps available online accessible to an inclusive audience. Sites and applications
that utilize maps should follow the same guidelines made for general web content. However,
maps are primarily a visual tool, and rely primarily on a person’s visual cognition to understand
them. This poses a problem for any users who have visual impairments.
2.2 Thematic Maps and Accessibility
A map is a visual representation, commonly used to plot geographic data. Maps are able to
convey information in a richer visual format that has not been achieved through the use of text,
tables, or graphs [21]. When dealing with complex data from a specific space and time, mapping
makes it possible to separate important factors and display them in a clear, concise manner. A
thematic map is a type of map that has a special purpose in order to convey a particular data set.
The intent is to understand the data in relation to the geographic area it is being overlaid upon.
The data set is layered on a base map that is more simplified than a general reference map. The
advantage of thematic maps is their ability to illustrate spatial relationship [20].
4
According to the World Wide Web Consortium (W3C) Web Content Accessibility Guidelines
(WCAG 2.0), Guideline 1.11
Text Alternatives: Provide text alternatives for any non-text content so that it can
be changed into other forms people need, such as large print, braille, speech,
symbols or simpler language.
To relate this to a thematic map online, the map itself, which is an image, needs to have a text
alternative in order to satisfy accessibility requirements. The W3C recommends that a short text
alternative be provided which serves the same purpose of the non-text content. A thematic map
is rich in data, which makes it difficult to translate into a short text description. A longer
description must also be provided in order to satisfy this guideline.
To help identify the solution to this problem, we tackle the issue in a unique way, such that we
are focusing on the most basic design of a web mapping application possible in order to provide
a text based alternative, instead of looking at widgets we can connect to or an assistive device
that can be used on top of web applications to enrich a visually impaired users experience, this
technique is aligned with the design approach of progressive enhancement [6]. Assistive devices
do have the potential to improve a user’s experience, however, through practicing progressive
enhancement we will ensure a web mapping application will be accessible in their barest form.
For a visually-impaired person, the way to access any data provided on the web is through text.
Maps provide a richer learning experience with more data than a table or chart could provide.
Ethically, a blind person should have access to this same information [22]. It may be argued that
the time needed to address this in web mapping applications is too time-consuming and costly
and that text-based solutions should be enough to satisfy accessibility. This view of text-based
pages has been referred to as the “ghettoization” of the Web [16] as it does not provide an equal
experience, and is really just the easy solution, not the best solution. The usefulness of this work
can be shown using the example of Environment Canada’s National Pollutant Resource Index
(NPRI)2. NPRI tracks and provides information on facilities in Canada concerning which
1
http://www.w3.org/TR/WCAG20/#text-equiv
2
http://www.ec.gc.ca/inrp-npri/default.asp?lang=en
5
emissions they are releasing and how much. They offer to Canadian citizens a web application
which provides the option of accessing this information through a text-based search or a webmapping application. The results returned from the text-based search are purely explicit: facility
name, location, emission, etc. They deliver information specifically about the thematic layer,
concerning each point and why it is being shown. The visual results returned from a map search
contain both explicit and implicit information, because they present the information available in
the thematic layer and overlay it on a base map in order to give the viewer more context for the
data being examined. It allows the user to more quickly identify the intrinsic impact of the
results. How close is this pollution to me and my loved ones? How many facilities are affecting
me? It has been shown that visually impaired people have the ability to process and understand
the implicit information such as spatial distribution [13]. We would like to understand if adding
this implicit information taken from a person’s visual understanding of a map would have any
impact on a visually impaired persons understanding of the information they are searching
2.3 Cognitive Mapping
The study of how a person makes sense of their spatial environment is called cognitive mapping.
It can be further defined as:
cognitive mapping is a process composed of a series of psychological
transformation by which an individual acquires, stores, recalls, and decodes
information about the relative locations and attributes of the phenomena in his
everyday spatial environment [8]
Every person, sighted or non-sighted creates a cognitive map of an environment. The techniques
used to do this vary depending on the information and senses available. Cognitive maps are
made up of relative positioning, attributive values and meaning, knowledge about places and
spatial relationships [13]. It is the cognitive map a sighted person created when viewing a map
that we are interested in translating to text.
2.4 Related Work
To address a visually impaired person’s understanding of spatial concepts, there has been work
done in the field of cognitive science to understand cognitive mapping [12], how we make sense
of our surroundings and how we use knowledge to make spatial decisions and choices [12].
6
Kitchin defines three knowledge structures which are used by sighted individuals in the context
of cognitive mapping.
Declarative: the mental database of specific features, such as landmark knowledge, roads, parks,
etc.
Procedural: the rules used to synthesize the declarative knowledge database into information
which can be used to facilitate an action. This includes wayfinding and strategies for determining
pattern, recognizing shapes, hierarchies, linkages, regions, and other spatial relations.
Configurational: the highest level of cognitive map knowledge. It surpasses procedural
knowledge by incorporating information such as angles, directions, orientation, location, and
distance between places [10] so the possessor has knowledge of the association between, and the
relative positions of places; these form a comprehensive spatial knowledge system [11].
When addressing the visually impaired community, declarative and procedural knowledge has
been the basis for studies performed in the field of human-computer interaction and ubiquitous
computing such as [2][3][4]which address wayfinding and context-aware navigational devices.
These studies have focused on the areas of wayfinding and context-aware devices, and have
looked at directional based mapping and the creation of assistive devices.
Bradley et al conducted a study in which sighted participants were interviewed and asked to
describe through text and speech, directions to various well-known destinations. From these
descriptions they were able to subjectively categorize the contextual information into nine
categories. The study was repeated using blind participants. Comparisons between the two
studies are shown in Table 1.
Table 1: Classes of contextual information used by sighted and visually impaired
participants
Class of contextual
Example
information
1. Directional
Left/right, north/south
% Used
% Used
sighted
vis imp
37.4
30.1
7
2. Structural
Road, monument, church
11.5
20.1
3. Environmental
Hill, river, tree
1.6
2.9
4. Textual-Structural
Border’s bookshop, Greaves Sports
9.9
1.2
Sauchiehall St., George Sq.
15.6
2.7
6. Numerical
First, second, 100m
5.0
7.5
7. Descriptive
Steep, tall, red
10.8
23.8
8. Temporal/Distance
Walk until you reach…or just before you
8.2
5.1
0
4.4
based
5. Textual-Area/Street
based
based
9. Sensory
get to…
Sound of cars passing or smelling a
bakery
10. Motion
Cars passing, doors opening
0
0.8
11. Social Contact
Asking people or using a guide dog for
0
1.4
help
These results show the categories that are apparent in descriptions given by participants;
however these are descriptions for wayfinding, based on procedural knowledge. This study is
interested on descriptions based on configurational knowledge.
Burrell et al tested a context-aware computing device. Participants were asked to use a locationsensitive college campus tour guide called Campus Aware. The participants were asked to
contribute notes concerning the location in order to gather user-created content concerning the
spaces around campus. The study categorized these notes as shown in Table 2.
8
Table 2: Concerning the quality of the notes, the study found that out of 129 notes:
Note Category
#of notes
Examples
Factual
70
“This is the agricultural library”
Opinion/Advice
59
“A great place to study or take a nap under a tree”
Snapshot
33
“This is where our men’s and women’s soccer teams live, sleep,
practice and compete.”
Humour
12
“This view has made proud men cry with abandon for their
mommies”
Questions
4
“who practices on these fields?”
Test/Error
4
“these groups of buil...” (incomplete)
The study uncovers the main categories for the types of information that were shared by
participants when describing the area of interest around them. From these two studies we are
able to understand the categories that are evident when giving a text descriptions of geographical
locations,. Although these studies involve directional maps and the use of procedural knowledge
in cognitive mapping, they show that the addition of contextual information is useful and also a
useful part of sighted and non-sighted persons geographical understanding.
We are interested in the cognitive mapping of an image, albeit a data-rich complicated image. It
is not a natural process to ask a sighted person to describe an image, simple or complex, as
senses can be taken for granted most often until a loss is experienced. The transcription of
images as rich as a maps has not yet been addressed however studies have been done on
describing simple images that are on the web [23]. These are images that can be described using
a short text description. Simple images face the same problem as complicated image maps when
trying to decide on what deems a description meaningful for the image in order to equate to the
visual experience.
9
3
Method
We wish to answer the question How does a sighted person describe a thematic map? We want
to be able to form a meaningful text description of a thematic map which will not just benefit the
blind community but also be meaningful to a general audience. In order to understand how to
form these descriptions, we must first poll the sighted community to understand how the visual
understanding of a map can be translated into words. Context and descriptions have been asked
of people before but only specifically in the area of direction-based mapping. The type of
cognitive map knowledge we are interested in interpreting has been termed configurational
knowledge [10] and includes information such as angles, directions, orientation, location and
distance between two points. This is the type of information available in a thematic map, and
that we know visually impaired people have the ability to understand these kinds of techniques
[13]. We want to be able to provide this type of knowledge in map descriptions, along with the
data that is readily available, the explicit data.
3.1 Study Design and Execution
The approach taken in this study is grounded theory [17]. In order to address the lack of a map
description, we wanted to find out how people who are accustomed to understanding and
interpreting spatial data visually would choose to describe a thematic map in text. From these
descriptions, we hoped to be able to see how explicit data as opposed to implicit data is used in
the descriptions to see if they were richer than a table of search results. We also hoped to create
a vocabulary of commonly used words, as well as common techniques used when asked to
describe a thematic map.
3.1.1
Early Iterations
We had originally designed the study to be a game with similar to the ESP [23] and Verbosity
[24] games developed by von Ahn and Dabbish. We intended to ask participants to play with
anonymous partners, with one creating a description of a map, while the other one was presented
with the description and the three possible maps it could represent. During paper prototypes of
this study we found that participants were “gaming” their description in order to gain points and
win the game quickly. This means participants would rely on techniques that were not
necessarily related to the meaning in a map, but more so if they would easily lead to a correct
10
guess. We found that they relied too heavily on the labels on the maps, either using the labels as
positioning devices, which did not assist in the comprehension of the map, but more so allowed
them to win the game easier and quickly, or as a “crutch” for their description. This prompted us
to redesign the study and take out labels on the map as well as take away the competitive aspect
of the study. This may be something that can be developed once guidelines and a framework for
map descriptions are available, but the game may have caused too many extra factors that were
not helpful for map descriptions, but helpful in order to win the game.
3.1.2
Web Application
We asked sighted participants to describe the map as they would to another person. Each
participant was given access to background information concerning the study as well as a
scenario that helped explain the research problem, definitions of web accessibility, thematic
maps and web mapping. We chose a web application as the format for this study as a way to
reach as many people as possible. We developed the web application using PHP and HTML
while storing data in a mySQL database.
3.1.3
Survey
Each participant was presented with a survey which was designed to review the participant’s
background, and their level of expertise in fields related to this study.
3.1.4
Map Descriptions
Cite the figure and talk about how long the descriptions were to be. The participants were
presented with the following background concerning the study:
Imagine you have just moved into a new neighbourhood.
To become better acquainted with your new area, you want to find out what parks
are around you and where they are located. You could perform a simple internet
search and get a listing of all the parks that fit the bill.
Better yet, you could display those results on a map.
11
Displaying a group of data in this way results in a thematic map. It displays
information concerning a particular theme spatially while using the underlying
map for context.
But a map is essentially an image, as it conveys all of its information visually.
What if you were not able to see images?
They were also given the option to review definitions for thematic maps, web accessibility, and
web mapping. They were given the following directions:
-
Imagine you are trying to describe a map to someone who can’t see it.
-
Please give at least one description of the data being displayed for each
map.
-
Try to be as clear and concise as possible.
-
You have the option of providing one or two more descriptions of the map
if you would like to take a different approach.
-
You are requested to describe 3 different maps.
12
Figure 1: Screenshot of Web Application
Move closer to section 3.1.3 and explain why 3 boxes
The maps included in the study were simple thematic maps showing sample point data. The
maps were from various extents and locations across Canada. Every map consisted of a base
map layer, which showed various features depending on the extent of the map. A landmark layer
was also included atop the base layer which showed features such as airports, ferry routes and
provincial parks. The order in which the maps were displayed was chosen randomly from a
13
possible eight maps. The participants had the option of describing the same map three times to
allow for the use of different techniques in their descriptions. The participants were shown three
different maps before they were thanked for their participation in the study and given the option
of ending the study or continuing and describing three more maps.
Accompanying each map was basic query data and a map title. The query data stayed the same
for all maps displayed. Participants were given the following sample query data information:
Map Title: Facilities Reporting Pollutant Releases
Report Year: 2008
Facilities: All Facilities
Substances: All Substances
Sector: All Sectors
Location: All of Canada
14
4
Results
4.1 Analysis
How many responses did I end up with, who did the analysis and how is it trusted?
The resulting data was cleaned by taking out participants who had filled in the survey but then
did not describe any maps, or filled in erroneous descriptions. Participant occupation was
analyzed and grouped into five different categories: Academia, Geography, Geographical
Information Systems (GIS), Information Technology, or Other. Their answers for level of
familiarity with Cartography, Web Mapping, Web Accessibility and Visual Impairment were
tagged as either “Little to None”, “General”, or “Expert”. Descriptions were edited for obvious
spelling mistakes in order to help with the coding of the descriptions. Descriptions were then
coded according to pre-defined classifications based on the categories found in Bradley et al’s
study; while adding new categories as they became evident. Keywords were grouped into their
appropriate categories. There were some overlaps and similarities between categories. Once the
keywords were tagged the context used for the keywords were analyzed in order to identify
techniques used for describing a map. The coding of all information was done by one person so
that consistent judgement was used.
The following categories and sub-categories shown in Table 3 were used to code the
descriptions:
Table 3: Thematic Map Description Categories
Category
1. Directional
2. Topographical
Sub-Category
Example
Cardinality
North, south, east, west
Placement
Left, right, up, down
Movement
Running, flowing, crossing
Divisional
Top, bottom, middle
Water Body
Lake, river, estuary
15
Land Mass
Island, shoreline, peninsula
Thoroughfare
Road, street, highway
Land/Water
Bank, coast, shore
Division
3. Quantitative
4. Shape
Rank
First, second, third
Grouping
Dozen, handful, multiple
Literal
circle, square, diamond etc.
Implied
jagged, smile-shaped, meandering etc
5. Landmark
Airports, parks, ferries etc
6. Query Data
Facilities Reporting Pollutant Releases,
2008, Substances etc.
7. Thematic
General
points, dot etc.
Specific
polluting sites, facilities etc.
Small, large, tiny etc.
8. Size
9. Jurisdiction
Extent
province, city, town, etc.
Community
neighbourhood, industrial, residential etc.
10. Colour
Blue, orange etc.
11. Distance
Km, cm, inch etc
12. Location
Montreal, St. John, Charlottetown etc.
The categories found for thematic maps are very similar to the categories from the Bradley et al.
study found in Table 1. The top ranking categories were the same; however our categories
16
include topics that take into account keywords that denote more generality than specifics. For
example, our classification framework has a category Shapes for pattern description and
distribution, whereas Bradley’s study has categories such as Textual-Structural based, and
Motion, which would only be applicable to directional-based maps.
4.2 Description Techniques
There were distinct techniques used by participants when structuring their descriptions. The
most popular technique used showed a progressive approach. The participants would start off
describing general overall impressions of the map and then focus in on more detailed features of
the map. Map features would be described and most often, the participant would describe the
points on the map last and use the features already described to give the point location context.
An example:
There is a large land mass cut by a river to the south large enough
to have several islands in it. There are roads in a general grid
pattern where possible cut by a highway running from northwest to
southeast. There are two facilities reporting pollution releases on
the north side of the river where the highway intersects the river
(towards the southeast) and one facility reporting pollution north of
those points and slightly to the east.
In this example the first sentence is general overview of the landmass. The second sentence
describes more detailed features of the map, the layout of the roads and highways. The last
sentence describes the points (the thematic layer) and uses the features already described such as
the river and highway to give the points’ context. Another example:
Imagine a small town. A river runs north-south. The town is
mostly built up along the east bank. At the south end of the town,
the river bends to go west before continuing south, so the south
part of the town is actually south and east of the river. Where the
river turns south again, it also forks northwest, shaped like a
divining rod or a letter "Y" A long road cuts across both branches
of the Y into town. On that road, west of the west branch, there is
17
one polluting site. Another polluting site is in the town, in the part
of town that is south of the river. It is on a train track that enters
the town from the southwest and bridges across the river at the
point of the Y. The final polluting site is north-east of the town.
The first half of this description is used to describe the base map and its features. The second
half is used to describe the points in relation to those features.
The next techniques included describing the thematic layer, and the base map was used as
context, but there was no separation of the two. For example:
There are six points marked on the map. Each of the points is
located near water; two are along a river while two are around
what appear to be a lake; the other two points, one of which is
marked by an airplane symbol, are near the sea/ocean.
The description of the points is the main goal, and all other categories are treated as secondary
and described only in relation to the points. Another example:
There are 5 points along the water. 2 points on a river in the center
of the map, two points on a lake on the west side of the map and
one on the sea on the north part of the map.
The resulting description is much shorter than the progressive approach.
4.3 Implicit vs. Explicit Data
Implicit data refers to parts of the description that has at this point in time, only been available
though viewing the thematic map. Explicit data refers to parts of the description that could
easily become available through a text-based search. Using the example we alluded to earlier of
NPRI, their text-based search results show information such as

facility id

facility name

address
18

substance report

city

province
We consider this information explicit data. Implicit data would be any piece of data that is
available only through viewing the map image cognitive mapping.
When considering the categories in Table 3, the following use predominantly implicit data:

Direction

Topography

Shapes
These three categories are ranked within the top four categories found in the descriptions. The
rest of the categories use mainly explicit information:

Quantitative

Landmarks

Query Data

Thematic
From these results we can conclude that a persons understanding of a map does not rely solely on
explicit data. Through visual cognition, the descriptions are highly influenced by implicit data.
A meaningful map description should contain both implicit and explicit data in order to be an
equivalent alternative to an image.
4.4 The Effect of Scale Level
We wanted to study the effect of scale level on participant’s descriptions. A map with a small
scale would depict a large area such as a country. Conversely a map with a large scale would
represent a small area such as a city center. Small scale maps offer more area coverage but with
less detail. The maps in the study were split in half concerning whether they were at a small or
large scale level.
19
Table 4: Category Ranking by Scale Level
Rank
Large Scale
Small Scale
Rank
Large Scale
Small Scale
[1]
Direction
Direction
7.
Query Data
Thematic
[2]
Topography
Topography
8.
Size
Size
[3]
Landmarks
Shapes
9.
Jurisdiction
Jurisdiction
[4]
Quantitative
Quantitative
10.
Colour
Colour
[5]
Shapes
Landmarks
11.
Distance
Location
[6]
Thematic
Query Data
12.
Location
Distance
Figure 2: Sample map of large scale
20
Figure 3: Sample map of small scale
4.5 The Effect of Jurisdiction
When describing a rural setting (an area where there is not a lot of variety to the map design) a
person will focus on a landmark (airport, park, etc.) in order to give their description some
context. Example of a map deemed rural and urban are shown in Figure 5.
When describing an urban setting the last five categories were less crucial in the description,
which can be seen in Table 5. The reason for this could be because there are already many
features in an urban map in order to give a description context. In a rural setting, there is less
variety and people are forced to reach and get creative.
Table 5: Category Ranking by Jurisdiction
Rank
Rural
Urban
Rank
Rural
Urban
1.
Direction
Direction
7.
Query Data
Jurisdiction
2.
Topography
Topography
8.
Size
Thematic
3.
Landmarks
Quantitative
9.
Jurisdiction
Size
4.
Quantitative
Shapes
10.
Colour
Colour
21
5.
Shapes
Query Data
11.
Distance
Distance
6.
Thematic
Landmarks
12.
Location
Location
Figure 4: Sample map of urban jurisdiction
Figure 5: Sample map of rural jurisdiction
4.6 The Effect of Missing Map Data
Some common cartographic features were deliberately left off the maps used in this study. There
22
were no labels, scale, legend, or compass. This was done in order to limit the participant’s
reliance on explicit data, which was noticed in the first iterations of this study. The absence of
these components resulted in many participants making up their own names to represent towns,
cities or scale in order to fill in the data. This shows that people are reliant on this data in their
understanding of a map. Example descriptions where this was apparent include:
This map displays the locations of (industrial?) facilities in Canada
reporting (liquid? airborne?) pollutant releases for the year of
2008. It identifies x such facilities, y of which are clustered around
an X-kilometre radius of (some unnamed body of water).
[I will finish still holding to that idea of describing point positions
relatively to a central reference. I can't really imagine doing it
otherwise] The map features the industrial suburb of Einstein in the
city of Science. There are three facilities. One of them north of
"the center" and the two others are south of it. [case north] The
facility is situated at about X km of "the center", but Y km by road.
[with an optional itinerary] [case south] The facilities are situated
at about X km of "the center", but Y km by road, and are really
close to one another, Y km, but Z km by road. [with optional
itinerary from "the center" (or any location the user might wish) to
one of the specific facility.]
(Note, I don't recognize this area, so I will make up some of my
description.) This map includes an area that is ___ kilometers from
east to west x ____ kilometers from north to south. North is on the
top. The background of the map is water and land, so the map
shows rivers, lakes, and larger bodies of water. The purpose of the
map is to display facilities reporting pollutant releases. The release
sites are displayed as dots. The map also shows navigation lanes,
parks and an airport. The discharge points are all on water bodies.
The northern most point is on an inlet one-quarter of the way down
the coast from the top of the map. Two other points in the western
23
portion of the map are on lakes. The final two points are on a river
that reaches the coast about ___ kilometers from the southern
boundary of the map.
4.7 The Context of the Keywords
When reviewing the context of the keywords and categories, we followed the practice taken by
von Ahn in their image labeling study [23]. A label was judged as good if it was agreed upon by
participants. We took the top five most popular keywords in each category. We chose the top
five as some categories did not have a very diverse keyword set as can be seen from Figure 1. An
exception was made for the distance category which had only 3 distinct keywords. These 5
keywords were viewed them within the context of their descriptions for each category.
Size
Shapes
Colour
Query Data
Jurisdiction
Quantitative
Direction
Landmarks
Topography
Location
Figure 6: Distinct Keywords by Category
Table 6: Top ranking words per category
Category
Top words
Direction
North, South, East, West, Bottom
Distance
Thematic
Size
Colour
Query Data
Jurisdiction
Quantitative
Landmarks
Location
Topography
Direction
Shapes
24
Topography
River, Water, Lake, Road, Ports
Landmarks
Airport, Park, Airplane, Symbols, Rail
Quantitative
Third, Second, Number
Query
Pollutant, Facilities, Release, Canada
Shapes
Cluster, Long, Tree, Scattered, Concentration/ed
Thematic
Points, Facilities, Dots, Sites, Diamonds
Size
Large, Small, Major, Tiny, Big
Jurisdiction
City, Town, Urban, Residential, Populated
Colour
Green, Blue, Yellow, White, Orange
Distance
Scale, centimeter (cm), kilometer (km)
Location
Nova Scotia, PEI, New Brunswick, Halifax, Cape Breton
4.8 Participant Results
We found the participants for this study by contacting the University of Toronto, Environment
Canada and the forwarding from contacted parties to those interested.
Descriptions were studied from 95 participants ranging in age from 19-61, with a mean age of 36
and a median age of 34. Participant’s backgrounds were mainly in Academia and Information
Technology.
Table 7: Participants By Age
Age Range
Total
0-19
2
20-29
25
25
30-39
36
40-49
13
50-59
13
60-69
2
Table 8: Participants by Field
Field
Total
Academia
26
i.e. Student, Researcher
Geography
11
i.e. Land Use Planner, Geospatial Analyst, Geomatics Specialist
Geographical Information Systems (GIS)
11
i.e. GIS Analyst
Information Technology (IT)
29
i.e. Software Developer, Technical Writer, System Analyst
Other
18
i.e. Sales, Lawyer, Meteorologist
We measured the skill level of each participant in topics related to this study, cartography, web
mapping, web accessibility, and visual impairment. The skill level can be seen in Figure 7.
26
70
# of Participants
60
50
40
Little to None
30
General
20
Expert
10
0
Cartography Web Mapping
Web
Accessibility
Visual
Impairment
Field
Figure 7: Participant Level of Expertise in Study-Related Fields
Table 9: Category Rankings by Field-Related Experts
Rank
Cartography
Web Mapping
Web Accessibility
Visual Impairment
[8]
Direction
Direction
Direction
Direction
[9]
Topography
Topography
Topography
Quantitative
[10] Quantitative
Quantitative
Quantitative
Shape
[11] Landmarks
Landmarks
Shape
Topography
[12] Shape
Shape
Query Data
Query Data
[13] Thematic
Query Data
Landmarks
Landmarks
[14] Query Data
Thematic
Thematic
Thematic
[15] Jurisdiction
Size
Size
Size
27
[16] Size
Jurisdiction
Jurisdiction
Jurisdiction
[17] Colour
Colour
Colour
Colour
[18] Distance
Location
Location
Distance
[19] Location
Distance
Distance
Location
4.9 Threats to Validity
4.9.1
Participant Background and Location
The background of the participants may have affected how the maps were described. A large
amount of participants were between the ages of 20-39. We did not have equal representation of
all age ranges. A large amount were also student or working in the area of Information
Technology or areas related to the study such as geospatial analysis, which could have
influenced the map descriptions. The location of people who took this study could have an affect
on the descriptions. It has been shown that familiarity of location and culture can affect the way
a person describes a location [19]. We accounted for this bias by using maps from one country,
Canada. We also asked participants to list all geographical locations that they have lived for six
months or more in their lifetime. Participants were predominantly from North America,
specifically Canada
4.9.2
Thematic Data
The query data provided in order to give the thematic layer context may have swayed the
descriptions. [Conventry at al] state that the words chosen by participants can be influence by
what they are describing. Given the knowledge that they were describing facilities which emit
pollutants, this may have effected the order and topics covered in the description, depending on
what that participant thought was important to the thematic topic or not.
4.9.3
Missing Data
The choice to exclude labels of any kind, a scale or a legend may have influenced the
descriptions.
28
4.9.4
Categorization of Data
The coding of all the data was completed by one person in order to allow the judgments made to
remain consistent. However, this entails a fair amount of subjectivity in the process which has
influenced the results of this study. To account for this subjectivity, results were reviewed and
verified by two people and their opinions were taken into account by the coder.
4.10 Forming Map Descriptions
A description of a thematic map should relay context through citing

Query data, for a general understanding of what the map is representing

Jurisdiction, for a specific area the map is covering

Location, to give real-life names to the area of jurisdiction
The points shown in the thematic layer should be described in relation to the various
topographical features and landmarks through comparing

Size

Distance

Direction

Placement
These descriptions are enriched through the use of descriptive words of the various layers and
their features, which relay

Shape

Size

Colour

Direction

Quantity
29
Figure 8: Map Sample
To show this framework in practice, here is an example map descriptions of the map shown in
Figure 8.
This map is showing locations of facilities which reported
pollutant releases in Canada in 2008. There is a town named
Springfield, which is based along the east bank of a river. The
river runs alongside the town from north to south. Approximately
half way down, the river is joined by a smaller river that arches
from the left. At the point where the two rivers join is a railway
track. There are 3 facilities shown, the first is at the terminus of
the railway track. The second point is located at the south end of
the town and to the east of the first point. There is a small park
near the center of town and bordering the east side of the river, as
well as an orange symbol over the river about X km north of the
park. The third point is due east of these two features, and is just
outside the north-east side of the town.
30
To understand how this description was formed based on the proposed framework, we have
broken it apart
Context
Query Data = “locations of facilities which reported pollutant releases in Canada in 2008″
Jurisdiction = “town”
Location = “Springfield”
Comparisons
Size = “smaller river”
Distance = “orange symbol over the river about X km north of the park”
Direction = “The second point is located at the south end of the town and to the east of the first
point.”
Placement = “There is a small park near the center of town and bordering the east side of the
river”
Descriptive Words
Shape = “that arches from the left”
Size = “There is a small park”
Colour = “orange symbol”
Direction = “The river runs alongside the town from north to south“
Quantity = “due east of these two features”
31
5
Future Research
The lack of work in the area of web mapping accessibility meant that the groundwork had to be
laid before we could actually answer the question of whether we are providing a richer web
experience for the visually impaired. Map descriptions could not be formed and tested until we
knew how sighted people interpreted maps, much in the same way static image description
databases are being generated through the tagging of images by sighted people.
Now that we have identified how sighted people describe maps, and proposed a framework for
those descriptions, we need to take the framework and test descriptions to the visually impaired
community in order to test it and see how it differs to a framework that would be more
meaningful to a visually impaired community.
This study focused only on thematic maps, and based much of its work on the abundance of
research in directional based maps. Yet there are many different types of maps and descriptions
may change depending on the map structure, just as cartographic techniques change depending
on the type of map that is being created.
To further the field of map descriptions for thematic mapping we can take another page from the
work done for the field of direction based maps and look at the role of user context. An
important way to tailor a map description would be to find out why the user is coming to view
the map in the first place. What is their purpose, or their intent in interacting with the map? It
may be more meaningful for a map description to be formulated around this purpose.
Considering a map is so rich in data, certain aspects may be more important to the user than
others, and through understanding the context it would be possible to filter out the data deemed
less important by the user. Burrell showed the effectiveness of allowing users to view and edit
the context note contributions of others. They were able to edit mistakes and approve
techniques. This could be an advantageous technique for mapping, and the description would
not have to be hidden in the HTML code to benefit only visually impaired users, but it could
prove to be a very useful piece of map metadata for an entire audience and could be featured
visually on the mapping web page for all users.
32
Most web mapping applications are highly interactive, which means the map view will
constantly be changing. The map description should also be changing to reflect this. The
creation of a dynamic description generator will be necessary as it won’t be feasible to create
descriptions for every possible view of the map.
When one of the senses are impaired, the load falls on the remaining senses to fill in the gaps. In
the accessible approach to a visual thematic map image we are currently only relying on audio
senses to address the gap. Basing this framework on creating a tactile way of interacting with
thematic maps as well would further enrich the experience for a visually impaired user [4].
33
6
Conclusion
We have been able to identify a framework which to base a thematic map description on in order
to bring a meaningful text alternative to a visually impaired community that is richer in meaning
than a text-based search of point information. Web mapping applications cannot currently meet
standard accessibility requirements as the map has no text equivalent, rendering the page useless
to the visually impaired.
34
7
Appendices
7.1 Thematic Maps
Thematic maps included in the study (smaller than study size)
35
7.2 Survey
Text-based version of online survey provided to participants:
Please take a moment to fill out the following...
Name:
Age:
Email:
36
Gender: Female/Male/Other
Occupation:
Do you have any visual impairment? If so, please list:
Please list the cities/towns you have lived in for 6 months or longer:
How familiar are you with the following topics:
NOTE: These are very broad topics, when answering please take into account your education,
career, personal experience or interest.
Please list what type of experience or knowledge you have concerning the topic of Geography.
(For example: Do you have any post-secondary education pertaining to the physical sciences?
Or does your job encompass the field of geography at all? )
Please list what type of experience or knowledge you have concerning the topic of
Cartography.
(For example: How familiar are you with the term cartography? Are you a cartographer, or
have you ever made a map before?)
Please list what type of experience or knowledge you have concerning the topic of WebMapping.
(For example: Do you use online mapping applications [ex. Google or Bing] extensively, for
what purpose? Have you ever created an online mapping application?)
Please list what type of experience or knowledge you have concerning the topic of Web
Accessibility.
(For example: Are you familiar with the term? Does an inaccesible webpage or application
affect your ability to interact with it meaningfully?)
Please list what type of experience or knowledge you have concerning the topic of Visual
Impairment.
(For example: Do you have a visual impairment or are you close to someone who has a visual
impairment?)
37
 I would like to receive future updates or outcomes related to this study.
7.3 Definitions
7.3.1
Thematic Maps
A map is a visual representation, commonly used to plot geographic data. Maps are able to
convey information in a visual format that has not been achieved through the use of text, tables,
or graphs. Thematic maps are used to display data concerning a particular subject. A layer
showing this data is overlaid atop a base map, where the base map used is a very simplified map.
7.3.2
Web Accessibility
Web accessibility is a term used to address the way in which web content can be used by people,
no matter their disability. This accounts for any cognitive or physical disability. The accessibility
guidelines observed by the Canadian federal government state that a text equivalent needs to be
present for all non-text content. Providing a textual description alternative of an image or graph
allows a person with visual impairment to understand what is present on a website.
7.3.3
Web Mapping
Web-mapping is the presentation of interactive map displays using the world wide web. A major
fault in the accessibility of web-mapping applications is its lack of a meaningful text description
of the map image area. Text-based searches have addressed how to extract the explicit map
information in order to provide it in a text format. There is still a wealth of information aside
from the explicit information that is available through a map, where no text description is
provided. This information needs to be translated into a text format to satisfy accessibility
requirements.
38
Bibliography
[1] Blades, Mark, Yvonne Lippa, Reginald G. Golledge, R. Daniel Jacobson, and Robert M.
Kitchin. “The Effect of Spatial Tasks on Visually Impaired Peoples’ Wayfinding
Abilities..” Journal of Visual Impairment & Blindness 96 (2002): 407–19.
[2] Bradley, Nicholas and Mark Dunlop. “Understanding Contextual Interactions to Design
Navigational Context-Aware Applications.” Human Computer Interaction with Mobile
Devices. Ed. Fabio Paternò. Volume 2411 of Lecture Notes in Computer Science.
Berlin, Heidelberg: Springer Berlin / Heidelberg, September 2002. chapter 37, 85–103–
103.
[3] Bradley, Nicholas A. and Mark D. Dunlop. “An Experimental Investigation into
Wayfinding Directions for Visually Impaired People.” Personal Ubiquitous Comput. 9
(November 2005): 395–403.
[4] Burrell, Jenna, Geri Gay, Kiyo Kubo, and Nick Farina. “Context-Aware Computing: A
Test Case.” UbiComp 2002: Ubiquitous Computing. Ed. Gaetano Borriello and Lars
Holmquist. Volume 2498 of Lecture Notes in Computer Science. Berlin, Heidelberg:
Springer Berlin / Heidelberg, September 2002. chapter 1, 647–653–653.
[5] Caddeo, Pierluigi, Ferdinando Fornara, Anna Nenci, and Amelia Piroddi. “Wayfinding
tasks in visually impaired people: the role of tactile maps.” Cognitive Processing 7
(September 2006): 168–169–169.
[6] Chamra, Debra. “Progressive Enhancement: Paving the Way for Future Web Design.”
TechJournal South, 2003 http://www.techjournalsouth.com/2003/09/progressiveenhancement-paving-the-way-for-future-web-design/. [Online, accessed 23-Sep-2010]
[7] Coventry, Kenny R., Angelo Cangelosi, Rohanna Rajapakse, Alison Bacon, Stephen
Newstead, Dan Joyce, and Lynn V. Richards. “Spatial prepositions and vague quantifiers:
Implementing the functional geometric framework.” IV. Reasoning, Action and
Interaction (Lecture notes in Computer Science. 2005, 98–110.
[8] Downs and Stea, Cognitive Maps and Spatial Behaviour: process and products 1973, p. 7
[9] Espinosa, M. “Comparing Methods for Introducing Blind and Visually Impaired People
to Unfamiliar Urban Environments.” Journal of Environmental Psychology 18
(September 1998): 277–287.
[10]
Golledge, Reginald G. “Representing, interpreting, and using cognized
environments.” Papers in Regional Science 41 (December 1978): 168–204–204.
[11]
Golledge, Reginald G. “Place recognition and wayfinding: Making sense of
space.” Geoforum 23 (May 1992): 199–214.
[12]
Kitchin, R. “Cognitive maps: What are they and why study them? .” Journal of
Environmental Psychology 14 (March 1994): 1–19.
[13]
Kitchin, Robert M., Mark Blades, and Reginald G. Golledge. “Understanding
spatial concepts at the geographic scale without the use of vision.” Progress in Human
Geography 21 (April 1997): 225–242.
39
[14]
MacEachren, Alan M. How Maps Work: Representation, Visualization, and
Design. 1 edition. The Guilford Press, June 2004.
[15]
Mitchell, Tyler. Web Mapping Illustrated: Using Open Source GIS Toolkits. 1
edition. O’Reilly Media, June 2005.
[16]
Regan, Bob and Andrew Kirkpatrick. “Multimedia and Graphics.” Web
Accessibility. Ed. John Karat, Jean Vanderdonckt, Gregory Abowd, Gaëlle Calvary,
John Carroll, Gilbert Cockton, Mary Czerwinski, Steve Feiner, Elizabeth Furtado,
Kristiana Höök, Robert Jacob, Robin Jeffries, Peter Johnson, Kumiyo Nakakoji,
Philippe Palanque, Oscar Pastor, Fabio Paternò, Costin Pribeanu, Marilyn Salzman,
Chris Schmandt, Markus Stolze, Gerd Szwillus, Manfred Tscheligi, Gerrit Veer, Shumin
Zhai, Simon Harper, and Yeliz Yesilada. Human-Computer Interaction Series. London:
Springer London, 2008. chapter 17, 287–299–299.
[17]
Seaman, Carolyn B. “Qualitative Methods in Empirical Studies of Software
Engineering.” IEEE Trans. Softw. Eng. 25 (July 1999): 557–572.
[18]
Spencer, C The child in the physical environment: the development of spatial
knowledge and cognition.., 1989
[19]
Suzuki, Koshiro and Yoshiki Wakabayashi. “Cultural Differences of Spatial
Descriptions in Tourist Guidebooks.” Spatial Cognition IV. Reasoning, Action, and
Interaction. Ed. Christian Freksa, Markus Knauff, Bernd Krieg-Brückner, Bernhard
Nebel, and Thomas Barkowsky. Volume 3343 of Lecture Notes in Computer Science.
Berlin, Heidelberg: Springer Berlin / Heidelberg, 2005. chapter 9, 147–164–164.
[20]
Tufte, Edward R. Visual Display of Quantitative Information. 15th printing
edition. Graphics Press, January 1997.
[21]
Tyner, Judith. Introduction to Thematic Cartography. Prentice Hall 1992.
[22]
United Nations, “Convention on the Rights of Persons with Disabilities and
Optional Protocol” Article 21(a) 2006.
[23]
von Ahn, Luis and Laura Dabbish. “Labeling images with a computer game.”
CHI ’04: Proceedings of the SIGCHI conference on Human factors in computing
systems. New York, NY, USA: ACM, 2004, 319–326.
[24]
von Ahn, Luis, Mihir Kedia, and Manuel Blum. “Verbosity: a game for collecting
common-sense facts.” CHI ’06: Proceedings of the SIGCHI conference on Human
Factors in computing systems. New York, NY, USA: ACM, 2006, 75–78.
[25]
Wilson, Jeff, Bruce N. Walker, Jeffrey Lindsay, Craig Cambias, and Frank
Dellaert. “SWAN: System for Wearable Audio Navigation.” October 2007, 1–8.
40
Investigating context-aware clues to assist navigation for visually impaired people Bradley,
Dunlop
UN Enable
Tufte book.
[1] Tyner Tyner, Judith 1992. Introduction to Thematic Cartography. Prentice Hall
NPRI http //www.ec.gc.ca/inrp-npri/default.asp?lang=en