A Tangible Visual Accessibility Tool for Interactive Tabletops

Lucile Cossou

, Sylvain Bouchigny

, Christine Mégard

, Sonia Huguenin

and Mehdi Ammi

CEA, LIST, LISA, 91191 Gif sur Yvette, France

LIMSI-CNRS, Université Paris-Saclay, Bât 508, Campus Universitaire F-91405 Orsay, France

Keywords: Interactive Tabletops, Accessibility, Visual Impairment, Tangible Interaction.

Abstract: Thanks to being highly multimodal, interactive tabletops show great potential for edutainment. But in order

to meet the world spreading inclusive school policies requirements, they need new and dedicated accessibility

tools which would take into account both the specificity of the platform and the needs of its users. We present

here the design methodology we adopted to design one of the said tools and the results we obtained.

1 INTRODUCTION

Serious gaming is gaining increasing importance in

classroom settings. Many works have shown that

games provide a motivating and error proof

environment for learning (De Freitas & Smith, 2007).

Moreover, it has been shown that direct manipulation

and collective work have a good impact on learning

(Verhaeg, et al., 2008). It is therefore not surprising

that in classrooms, educational games usually come

as board games. Other works also stress out that

videogames are efficient at motivating pupils and can

simulate highly complex situations that would be

difficult to access otherwise (Knibbe, et al., 2015).

Consequently, many teachers include the use of high-

tech devices, such as computers and tablets in their

curriculum.

Along with these tools, several past works pointed

the potential of Interactive Tabletops as they start to

reach the general market (Kubicki, et al., 2015). Like

board games, Interactive Tabletop games can benefit

from direct tangible interaction (Kaltenbrunner,

2009). Furthermore the layout of the table itself

facilitates collaborative applications (Scott, et al.,

2003).However, since many countries adopted

inclusive classroom policies (UNESCO, 2017)

regarding disability, teachers also need to take into

account accessibility requirements when proposing

edutainment activity to their pupils.

When considering retail interactive tabletops as a

mean to ease the integration of these requirements, we

find out that most of them provide the same

accessibility features as those embedded in traditional

devices, such as magnification, text to speech, colour

switch, contrast enhancing, etc. But all of these

adaptations have been designed for personal and

individual use. They often apply changes to the full

interface and take inputs from only one user at a time.

Therefore, they paradoxically have limited use in a

multi-user mixed-experience environment, such as in

classrooms.

Consequently, there is a need for new accessibility

features and modalities specifically designed for

Interactive Tabletops.

Also, previous studies show that teachers often

feel unequipped to teach to disabled students, and

sometimes feel they lack training on the topic of

digital content accessibility. Especially, they often

lack the technology skills to help their students use

assistive technology and therefore access ICT lessons

or educational technology tools (Smith & Kelly,

2014). Therefore, we decided to include teachers into

the design process of accessibly features for

Interactive Tabletop games.

Since there are many different kinds of disability,

and different ways to cope with these issues, the

needs regarding digital content accessibility on

Interactive Tabletops are numerous. As most of the

Interactive Tabletops only use their screen as their

feedback interface, visual accessibility is an

important matter for these devices. We have selected

as a first step a visual accessibility tool to study

tangible aids on tabletops by focusing on the zoom

modality. This work benefits from a user centred

approach to define the basic design. This tool takes

into account not only the specific needs of intended

users but also those required to collaborate around a

shared interface, based on teachers’ and special needs

Cossou L., Bouchigny S., MÃl’gard C., Huguenin S. and Ammi M.

A Tangible Visual Accessibility Tool for Interactive Tabletops.

DOI: 10.5220/0006504401260133

In Proceedings of the International Conference on Computer-Human Interaction Research and Applications (CHIRA 2017), pages 126-133

ISBN: 978-989-758-267-7

education specialists' inputs.

In the first part of this paper, we will discuss

related work regarding ICT accessibility and

Interactive Tabletops. After which we will describe

the design method we used and its result. Then, we

will present the tool itself and its implementation.

Finally, we will discuss the results and the future

steps of this study.

2 RELATED WORKS

2.1 Digital Content Accessibility

According to the World Health Organization (World

Health Organization, 2012), about 246 millions of

people around the world, among which 17.6 millions

of children, have low vision. Vision impairments can

be of a lot of different nature, ranging from refractive

error to photophobia including tunnel vision and

scotoma. Among 8% of the world population is also

color deficient or color blind (Chan, et al., 2014).

Visual impaired people often have to face social

inclusion challenges (Duquette and Baril, 2008)

which may be increased by their difficulty to access

digital content (Smith and Kelly, 2014) .

On smartphones or tablets, users are able to

magnify content through application related features

or the operating system accessibility tools (American

Foundation for the Blind, 2017). These features are

often gesture activated: e.g. “pinch to zoom” is a

common gesture to magnify content in applications

and Apple, Android and Microsoft all use multi-

finger multi-taps on screen to activate or deactivate

full-screen magnification. The operating system can

also provide contrast enhancing or other visual

improvements, Apple's one even allows their users to

use a magnifying window instead of full screen

magnification.

But the digital accessibility effort cannot be

sustained by the operating system developers alone.

Applications' content itself has to be made accessible

by their developers, either because of the multimedia

nature of the content (like videogames for example),

or because of the need to follow certain rules of

development to allow most accessibility tools to work

properly (like websites). These last years, these

matters gained more awareness from many different

actors. Associations and organizations such as

AbleGamers (AbleGamers Foundation, 2016) or the

W3C (W3C, 2017) published accessibility guidelines

aimed at digital content developers for computer

games and online websites, and many actors of the

digital content industry started to develop

accessibility settings for their products (IGDA Game

Access SIG, 2017). In addition to these settings, many

third-party assistive technology exist such as text-to-

speech software, lenses or braille terminals. Also,

many start-ups and research teams work on new

interfaces and devices to enhance digital accessibility

such as braille tablets (BITLAB, 2017) or special

controllers (Evil controllers, 2016).

The wide range of solutions and devices available

reflects the different sight impairing disabilities and

the different solutions disabled people might choose

from. They are usually very specialized pieces of

equipment.

2.2 Interactive Tabletops

Interactive Tabletops are relatively new on the

market.

They can use different kind of technology. Some

of them are only tactile and use the same capacitive

sensing method found in tablets, smartphones and

computer screens (Barrett and Omote, 2010). Others

use optical sensing, and are able to sense both touch

interaction and object interactions (Maxwell, 2007).

There are also some tabletops which use resistive

RFID sensing technology (Kubicki, et al., 2009) and

are only able to sense objects.

The available literature shows the opportunities

given by bringing together touch sensing technology,

objects recognition and tracking on a large surface

display. Also, many works emphasize on how

Interactive Tabletops can sustain collaborative

activities (Scott, et al., 2003) and on the affordability

of tangible objects interaction (Tuddenham, et al.,

2010).

However, due to their expensive price, their use is

still mainly restricted to public areas such as

museums, restaurants, and schools. Most of them do

not benefit from a dedicated operating system and use

the same OS as personal computers which have been

designed for individual users and therefore cannot

offer different accessible multi user experiences

2.3 Interactive Tabletops and

Accessibility

Several research groups already worked on the topic

of accessibility on Interactive Tabletops.

Ortea et al. (2011) designed and developed several

frameworks dedicated to prototyping educational

games for young children. Their research included

different use cases, including the design of those

games for children with cognitive impairments.

Kunz et al. (2014) worked on an inclusive

brainstorming interface for Interactive Tabletops that

would allow both sight impaired and not sight

impaired users to collaborate.

Some other works also focused on other specific

situations such as graph design tools (McGookin, et

al., 2010), rehabilitation (Duckworth, et al., 2015) or

map exploration (Ducasse, et al., 2015)(Brock, 2013).

2.4 Magnification and Interactive

Tabletops

Although not specifically designed for accessibility

purposes, many papers describe the use of

magnification (or similar feature) tools on Interactive

Tabletops.

These works mostly include data visualisation

(Tominski, et al., 2014) and map exploration

(Forlines and Shen, 2005) applications. Many of them

(Tominski, et al., 2014) rely on the Magic Lenses

concept, introduced by Bier et al (1993) a few years

ago, which allow users to access different layers of

representation of one same information. They use

virtual (Forlines and Shen, 2005) representations of

lenses or tangible ones such as transfer paper (Kim

and Elmqvist, 2012), cardboard (Spindler, et al.,

2010) or more or less transparent plastics (Büschel, et

al., 2014).

2.5 Contribution

While there have been quite a number of works on

interactive tabletops accessibility, most of them are

focused on very specific applications and do not

really aim to provide personalized accessibility

features. This is also true for quite a part of the

available literature on visual transformation lenses for

interactive tabletops. Moreover, we are not aware of

any work focusing on the use of this kind of visual

transformation lenses for accessibility purposes on

interactive tabletops.

We conducted some focus groups and interviews

with inclusive or specialized school teachers and two

brainstorming sessions with education accessibility

and rehabilitation specialists. The results of these

interviews and creativity sessions gave us a first

insight of our users' needs and we would like to

propose a tool which could be embedded in many

different kinds of educative multimedia applications

while also providing a more personalized

accessibility feature to its users.

3 DESIGN METHOD

Because of healthcare and child safety and privacy

regulations, visually impaired pupils are a difficult

public to have access to. Literature review also shows

that one of the most important factors in the lack of

adoption of assistive technologies and use of ICT

with disabled pupil is the feeling of lack of

competencies of their teachers. Therefore, we decided

to focus on teachers’ insights first, in order to better

understand what are their needs regarding

accessibility of educational games. We also have

access to previous data from interviews, conducted by

our collaborators, of 19 teachers. Four of the

interviewed teachers answered being working in

lambda schools. Two others reported being working

with hospitalized children. And the other recruited

answered teachers being working either in inclusive

or specialized classrooms and had pupils in their class

who were either sight impaired of hearing impaired

or had cognitive disabilities.

While the interviews did not focus on

accessibility issues, some teachers still expressed

some of the difficulties they encounter while working

with inclusive classes. Some of the concerns

expressed include: the need for an adaptation of the

study material to each student’s specific situation, the

lack of available accessible digital resources "There

are plenty [educative video games] I don't use […]

they are not made for sight impaired pupils", the cost

in time of the preparation of ICT.

This data helped us design our own user study,

and we conducted three focus groups on accessibility

on interactive tabletops in serious games. These focus

groups and their results are described in the following

subsections.

3.1 Focus Groups

Half of the teachers previously interviewed were

recruited for three new focus groups. All of them

worked either in specialized or inclusive classroom or

with hospitalized children. In order to make those

groups a little bit bigger and to get a better group

dynamic, two disabilities and teaching experts and

one serious game experts were invited to join the

process.

After a short technical demonstration of an

interactive tabletop working with tangible objects,

they were encouraged to discuss the use they would

make of Interactive Tabletops as a game installation

in their classrooms.

During these discussions, they talked about the

different kind of games they would like to use,

proposing simple applications (e.g. quiz, timeline-

based games, maze exploration, collaborative story

creation) as well as more complex ones (e.g. treasure

hunt, construction game, virtual world with many

different quests).

They also specifically evoked the software

features they would like to be able to propose to their

pupils to make their digital learning activities

accessible on interactive tabletops. Ideas that were

mentioned included functionalities such as sign

language subtitling, sound producing objects,

brightness and contrast tuning, or the possibility to

magnify specific areas of the tabletop.

Furthermore, they underlined that given the fact

that each child is different and has different needs

regarding their impairment situation, the teachers

need to be able to adapt the content of their

applications to each individual situation.

They expressed the desire that their pupils be able

to explore the content displayed on the interactive

tabletop surface both collaboratively and

individually.

They also emphasized that the tangible objects

proposed would "need to be steady" (a teacher)

because pupils are not always cautious with their

tools.

3.2 Creativity Sessions

After the focus groups, we conducted two creativity

sessions with 6 special education specialists based on

the results of the previous interviews.

3.2.1 First Creativity Session

For the first brainstorming, we presented the teachers

a simple demonstration with a virtual magnifying

window as a way to fuel the discussions. This

magnifying window enabled enlarging the underlying

Figure 1: Magnification demonstration.

content simply by moving it to different locations on

the screen using a tangible pointer. (See Figure 1).

During this first session, several interaction

modalities were discussed, such as tangible object

manipulation, touch gestures, split screen use or

virtual objects manipulation. All participants also

evoked the importance of the need for more

accessibility features than only the magnifying one

(as did the teachers in the preliminary studies) and the

need for personalized tools.

Scenario 1

Scenario 2

Scenario 3

Scenario 4

Figure 2: Demonstration Scenarios, one scenario per row,

from top to bottom:

Scenario 1: Common pinch to zoom gesture

Scenario 2: point with a token and display adapted content

on the side

Scenario 3: Put down a tangible on the table and make a

gesture to activate adaptation of content

Scenario 4: Use a button to switch on content adaptation.

From this first session, we extracted several

interactions modalities (based on both touch and

tangible interactions) that we gathered into a first

interaction modality dictionary. Second creativity

session

During the second creativity session, we

illustrated four magnifying action scenarios, after the

propositions made during that first brainstorming

session (see Figure 2) and presented them to the same

panel for the second brainstorming session. This gave

the experts to brainstorm based on existing ideas

rather than from scratch in order to help spark ideas.

For instance, they could simply discard solutions by

crossing them (e.g. only touch based interactions) and

make some new recommendations.

Specifically, the use of a tangible frame as a zone

of interest pointer seemed to reach consensus.

These exchanges also emphasized the need for a

fine step decomposition of interaction scenarios as

they expressed difficulties to detail the exact steps

needed to perform the scenario.

3.3 Intermediary Results

3.3.1 Recommendations

Those discussions lead up to the redaction of a first

list of recommendations for the design of a tangible

visual accessibility tool for interactive tabletops.

The tangible object has to be non-obstructive, in

order to make collaboration around the table easier,

while still being visible for a sight impaired person,

which means it has to be preferably be large with

bright colors. The same constraints apply to the limits

of the window that displays the adapted content.

These limits can be represented either as a tangible

frame or a virtual one.

Also, following insights from the brainstorming,

displaying the adapted content on a fixed and separate

window (see 3

line in Figure 2) should be avoided

since it can lead to more cognitive load and be

confusing in a multiuser settings.

In order to facilitate the use of such an object

without monopolizing either both hands of the user or

their attention, the object should consist of one single

piece of hardware.

Finally, so that users could move freely around the

table and share their work more easily, they should be

allowed to change the orientation of the part of the

screen they are visualizing.

3.3.2 Magnifying Step Decomposition

During the brainstorming sessions, we identified the

need for a decomposition of the “accessing accessible

content” action into five more specific sub-actions.

We defined five of them:

• “point”: select the item or zone of interest on the

surface

• “display”: apply accessibility settings on the

zone of interest of the surface and render the

transformed output

• “change the display”: change the transformation

settings of the zone of interest

• “share”: make the zone of interest visualized

visible for other users

• “back to normal state”: remove any accessibility

transformation applied in order to bring back the

zone of interest to its first state.

In a scenario, the sub-action “change the display”

and “share” are optional in the sense that it is possible

to purposely have a scenario that does not make these

options available (for example in the case of usage by

students with cognitive disabilities who could be

disabled by this kind of features).

4 FINAL CONCEPT

Figure 3: The content inside of the frame is directly adapted.

While the interviewees proposed diverse solutions

(split-screen, taking turns on being the main user of

the screen, making the tap gesture a magnifying

interaction by default…), the one that reached the best

acceptance was about using a tangible frame. It

answered most of their recommendations. If is flat

thus not obtrusive. Its tangible borders make it a good

way to separate the adapted content (inside of the

frame) from the original one (outside of the frame). It

also allows for direct and clear interaction with the

tabletop, since the adapted content is linked with the

frame position.

We used the five steps decomposition and the

inputs we got from the interviewees and the

preliminary study to expand on this idea and propose

the following scenario:

• Point: the pupil places a tangible frame around

the point of interest he wants to magnify. The

frame being almost flat, the other users can still

see what is around and inside the frame.

• Display: the picture contained into the frame is

magnified automatically. This allows the picture

to be displayed in its direct context; just the same

way it would when the user uses an analog lens.

• Change the display: the student can change the

magnifying level using a virtual cursor

embedded on the side of the frame.

• Share: the pupil can rotate its frame to rotate the

view and make its content more understandable

by the other students who are not standing from

the same side of the table.

• Back to normal state: when the student removes

the frame, the magnified picture goes back to its

original aspect with its normal orientation. All

the modifications of the magnifying frame

settings the pupil made by manipulating the

cursor will be saved by the cursor position and

reused.

5 IMPLEMENTATION

Figure 4: Fiducial markers and tangible object.

The Interactive Tabletop we use for our work is a

Multitaction optical table. It uses infrared sensitive

video-cameras to perform touch and object detection.

Object recognition is achieved through the use of

squared black and white tags pasted on the bottom of

the objects (see Figure 4) which are in direct contact

with the tabletop’s surface. The position of such

objects and fingers is then transmitted to the

tabletop’s software applications thanks to a

communication protocol named TUIO

(Kaltenbrunner, 2009).

5.1 Tangible Object

The frame was designed to answer the needs

expressed by the teachers and the experts. It has been

3D printed in order to be bold and sturdy, while still

being light. It was painted in red to make it more

Figure 5: Tangible frame, bottom and top.

visible on the tabletop surface.

The frame is detected by the interactive tabletop

using two paper made fiducial markers placed at the

back of the frame on two opposite corners (see Figure

5). This allows the software to track not only the

position of the frame, but also its size and its

orientation, and hence allows the use of any size of

frames.

While we made this frame with a 3D printer, it

could easily be built with cheaper materials such as

cardboard or papier-mâché while still meeting the

user needs evoked in the previous part of this article.

5.2 Software

To stick with the idea of providing such an

accessibility tool for different kinds of educative

games, we used Unity3D (Unity Technologies, 2017)

to develop our demonstration. Unity is a broadly used

game engine which allows many kind of realisations

such as interactive demonstrations, commercial video

games or educative games.

Figure 6: Tangible frame in application.

We developed a picture exploration application

featuring the frame and coded the frame interactions

to be as close as possible as to the scenario proposed

during the creativity sessions.

Using the TUIO data transmitted by the

interactive tabletop internal software, we can track

the positions of the two tags which are placed under

the frame and compute the size, position and

orientation of a virtual window which might fit inside

the frame. Thanks to the frame using two tags and not

just one, we are also able to provide a more robust

tracking of its position. It allows us to handle more

situations, for instance those when the frame is only

partially on the tabletop, since it is likely that at least

one of the two tags embedded below the frame will

be on the surface. This also allows us to use the frame

on the edges of the tabletop.

In this window, we display a replica of the content

contained within the frame. We apply all the visual

modifications required by the frame owner to this

replica.

These modifications can include contrast

enhancing, contour colouring, background hiding,

colour shading, brightness tuning or magnification

and are processed by the interactive tabletop

graphical processing unit. The combination of all

those modifications can be made through code or

using a visual interface and is stored into a user

profile. This profile is attached to a unique frame,

each frame having its own unique set of fiducial

markers.

The application can track and provide

accessibility content to any possible number of

frames within the space of the table, allowing

multiple users to explore the picture simultaneously.

6 CONCLUSION AND FUTURE

WORK

We co-designed and proposed tangible accessibility

tools specifically aimed to respond to interactive

tabletops shared interface specificities. The

interviews and creativity sessions allowed us to

identify several key features (weight, non-

obstruction, embodiment into a single device, bright

colored…) for the design of such kind of objects. The

implementation of the solution allows us to easily

include this tool into our game development process.

Since accessing young disabled population is

difficult, more specifically in a classroom setting, we

conducted all our preliminary studies and interviews

with professionals of the accessibility field and

teachers. As a next step, in order to validate our

proposition and improve it, we plan to conduct a user

study directly with the end users we target, i.e.

students of different ages, both visually and sighted,

in a classroom setting.

This will allow us to gather direct user feedback

on our proposition and apply an iterative design

methodology on our system.

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