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

ii

Describing a Thematic Map

Alecia Fowler

Masters of Science

Graduate Department of Computer Science University of Toronto

2010

Abstract

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excluding title. Do not include graphs, charts, tables, or illustrations in the abstract.

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Acknowledgments

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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

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 .................................................................................................. 11

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

4.7 The Context of the Keywords ........................................................................................... 23

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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 ......................................................................................................... 28

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

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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: .................... 7

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 ..................................................................................... 24

Table 7: Participants By Age ........................................................................................................ 24

Table 8: Participants by Field ....................................................................................................... 25

Table 9: Category Rankings by Field-Related Experts................................................................. 26

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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

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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

[19]. There has been an abundance of research done on meaningful context-based descriptions

when addressing directional maps and wayfinding [9][26][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 [23] 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

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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.

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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 [22]. 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 [21].

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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 [23]. 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

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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 web-

mapping 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].

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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

information

Example % Used

sighted

% Used

vis imp

1. Directional Left/right, north/south 37.4 30.1

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2. Structural Road, monument, church 11.5 20.1

3. Environmental Hill, river, tree 1.6 2.9

4. Textual-Structural

based

Border’s bookshop, Greaves Sports 9.9 1.2

5. Textual-Area/Street

based

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

based

Walk until you reach…or just before you

get to…

8.2 5.1

9. Sensory Sound of cars passing or smelling a bakery 0 4.4

10. Motion Cars passing, doors opening 0 0.8

11. Social Contact Asking people or using a guide dog for

help

0 1.4

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 location-

sensitive 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.

Table 2: Concerning the quality of the notes, the study found that out of 129 notes:

Note Category #of notes Examples

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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 [24]. 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.

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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 [18]. 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 [24] and Verbosity

[25] 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

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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. For example

when describing the points in and around a town called “Cemetery” one test participant gave the

hint:

2 dots that touch [the letter] “y” in label “Cemetery”

This gives no real geographical context, as positioning of labels can vary. The primary role of

labels on a map is as a locative device; the positioning of labels relies on many different factors

and depends on the style of the cartographer[17]. In pursuit of simplicity the study was

redesigned and the labels and all other textual information were left off of the maps such as scale

and compass. We also took away the competitive aspect of the study. The tradeoff of this

decision is that we are not allowing participants to utilize any of the other information that is

available through the use of labeling such as comparing type-size, colour, or style to denote

population or jurisdiction differences or the understanding of actual distance represented on the

map. 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. We found the participants for this study by contacting

the University of Toronto, Environment Canada as well as word of mouth, using posters and

email which contained the url to the study.

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.

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3.1.4 Map Descriptions

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.

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.

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Figure 1: Screenshot of Web Application

A screenshot of the map description area can be seen in Figure 1. 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 possible eight maps. The

participants had the option of describing the same map three times (Description A, B and C) to

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allow for the use of different techniques in their descriptions, however it was only mandatory to

fill in text for Description A. Each description allowed for 1000 characters. 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

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4 Results

4.1 Analysis

KHAI: I am still working on addressing this “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, resulting in 285 examples for

Description A, 50 for Description B and 18 for Description C. 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 Sub-Category Example

Cardinality North, south, east, west

Placement Left, right, up, down

Movement Running, flowing, crossing

1. Directional

Divisional Top, bottom, middle

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Water Body Lake, river, estuary

Land Mass Island, shoreline, peninsula

Thoroughfare Road, street, highway

2. Topographical

Land/Water

Division

Bank, coast, shore

Rank First, second, third 3. Quantitative

Grouping Dozen, handful, multiple

Literal circle, square, diamond etc. 4. Shape

Implied jagged, smile-shaped, meandering etc

5. Landmark Airports, parks, ferries etc

6. Query Data Facilities Reporting Pollutant Releases,

2008, Substances etc.

General points, dot etc. 7. Thematic

Specific polluting sites, facilities etc.

8. Size Small, large, tiny etc.

Extent province, city, town, etc. 9. Jurisdiction

Community neighbourhood, industrial, residential etc.

10. Colour Blue, orange etc.

11. Distance Km, cm, inch etc

12. Location Montreal, St. John, Charlottetown etc.

16

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

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

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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

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

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address

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.

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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

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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 [24]. 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 Colour

Query Data

Jurisdiction

Quantitative

Landmarks

LocationTopography

Direction

Shapes

Distance

Thematic

Size

Colour

Query Data

Jurisdiction

Quantitative

Landmarks

Location

Topography

Direction

Shapes

Figure 6: Distinct Keywords by Category

24

Table 6: Top ranking words per category

Category Top words

Direction North, South, East, West, Bottom

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

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

25

20-29 25

30-39 36

40-49 13

50-59 13

60-69 2

Table 8: Participants by Field

Field Total

Academia

i.e. Student, Researcher

26

Geography

i.e. Land Use Planner, Geospatial Analyst, Geomatics Specialist

11

Geographical Information Systems (GIS)

i.e. GIS Analyst

11

Information Technology (IT)

i.e. Software Developer, Technical Writer, System Analyst

29

Other

i.e. Sales, Lawyer, Meteorologist

18

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

0

10

20

30

40

50

60

70

# o

f P

art

icip

an

ts

Cartography Web Mapping WebAccessibility

VisualImpairment

Field

Little to None

General

Expert

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 students or professionals working in the area of

Information Technology and areas related to the study such as Geographical Informtion Systems

(GIS), 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

[20]. All maps used in this study were representing an area of Canada to make it easier to track

if participants were familiar with the area and culture. 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 with 71 out of a possible 95

participants stating that they have lived in an area of Canada for over 6 months.

4.9.2 Thematic Data

The query data provided in order to give the thematic layer context may have swayed the

descriptions. Words chosen by participants can be influenced by exactly what they are

describing [7]. 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.

28

4.9.3 Missing Data

The choice to exclude labels of any kind, a scale or a legend may have influenced the

descriptions. The lack of traditional cartographic elements such as labels, scale and compass

may have cause participants to describe a map in a way that seemed unnatural to them.

However, the act of describing a map is not an easy or common task so there was some level of

discomfort in the task already. Many participants accounted for this by making up their own

data in order to form their description.

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

29

Colour

Direction

Quantity

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

30

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.

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 present the framework to a visually impaired audience for

opinions and feedback. We also need to form descriptions based on the framework and call upon

a sighted and non-sighted audience to test the level of meaning and understanding.

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 Web-

Mapping.

(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/progressive-enhancement-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] Robinson, Arthur H., Joel L. Morrison, Phillip C. Muehrcke, A. Jon Kimerling, and Stephen C. Guptill. Elements of Cartography. 6 edition. Chapter 22. Wiley, March 1995.

[18] Seaman, Carolyn B. “Qualitative Methods in Empirical Studies of Software Engineering.” IEEE Trans. Softw. Eng. 25 (July 1999): 557–572.

[19] Spencer, C The child in the physical environment: the development of spatial knowledge and cognition.., 1989

[20] 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.

[21] Tufte, Edward R. Visual Display of Quantitative Information. 15th printing edition. Graphics Press, January 1997.

[22] Tyner, Judith. Introduction to Thematic Cartography. Prentice Hall 1992.

[23] United Nations, “Convention on the Rights of Persons with Disabilities and Optional Protocol” Article 21(a) 2006.

[24] 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.

[25] 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.

[26] 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