Janet Van Der Linden
email: janet.vanderlinden@open.ac.uk

Yvonne Rogers
email: y.rogers@ucl.ac.uk

Tim Coughlan
email: tim.coughlan@nottingham.ac.uk

Anne Adams
email: anne.adams@open.ac.uk

Caroline Wilson

Pablo Haya
email: pablo.haya@uam.es

Estefanía Martín
email: estefania.martin@urjc.es

Trevor Collins
email: trevor.collins@open.ac.uk

Evocative Computing -Creating Meaningful Lasting Experiences in Connecting with the Past

Keywords: pervasive computing, user experience, heritage practice, memories, evocative computing 1

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

The lives of people from different times and places are preserved through cultural heritage sites, and as stories about them are passed on through generations, they provide us with a sense of humankind's history. We may, for example, consider our own eating habits and food preparation methods when we visit the kitchens of an old cas-tle, and see the layout, the pots and pans and the recipes that were used all those years ago. Ubiquitous computing technologies are increasingly being used to augment such artifacts to help us delve deeper when exploring historical sites and museums. Museums often provide interactive exhibitions, digital information points and mobile guides, making it possible for people to hear or read about relevant information relating to the artifacts that are close by. There are however some concerns about the introduction of such technological tools, not only about their design and usability, but also about how they impact on the visitor experience as a whole. The social qualities of visits to such places can be impaired when using isolating single user tools, and it remains a challenge as to how to create experiences that are engaging and that draw visitors in -so as to enhance the visitor experience and to enable people to relate this to their own personal histories [START_REF] Ciolfi | Including Visitor Contributions in Cultural Heritage Installations: Designing for Participation[END_REF].

A number of researchers have designed visitor experiences with the aim of creating more engaging, participative approaches for people to explore history and the arts. These include setting up a game-playing environment in a museum [START_REF] Wakkary | Kurio: a Museum Guide for Families[END_REF]; providing tools where people can record their memories in outdoor settings so that they can be listened to by other visitors [START_REF] Mcloughlin | Design Interventions for Open-Air Museums: Applying and Extending the Principles of "Assembly[END_REF] and setting up special rooms and interactive objects for reflection and sharing opinions [START_REF] Ciolfi | Including Visitor Contributions in Cultural Heritage Installations: Designing for Participation[END_REF]. However, cultural heritage is not just found in museums but also in our physical environment and in the stories we tell around them; the buildings we live in, the monuments, installations and statues erected in memory of people who have died, and the objects we use as we go about our daily life.

Our research is concerned with taking this one step further: how can we design and use technologies to support the processes of reflecting and sharing of memories for historical sites, situated outdoors (such as cemeteries, roman ruins, castles)? In particular, we are interested in how a historical place can be brought alive, and histories revealed through discovering and learning more about the lives of the people who lived or are buried there.

User involvement can make the visit itself more engaging, but what happens after the visit? How can we go beyond creating environments where people can record their own perspectives, opinions and memories, to creating environments that enable people to make new associations between their own lives and the present visitor experience in meaningful and enriching ways? Can these both be felt in the moment as well as reflected upon later? If so, how can we design technologies to engender such moments, where new insights, emotional reactions, flashes of understanding and connections are made [START_REF] Barnes | Magical' Moments in Mathematics: Insights into the Process of Coming to Know[END_REF] -without knowing in advance what form they might take? Our approach: evocative computing, is an attempt to enable serendipitous enrichment and reflection in life: providing opportunities for personal memories to surface in ongoing activities that will result in them being forged and cemented in deep and long lasting ways.

To this end, we developed an assortment of distributed digital technologies -designed and configured for people to be able to readily pick up and put down, use momentarily or 'stumble upon' in the context of their activities. These were deployed in the setting of an old cemetery by a number of different community groups uncovering the stories of the people that lay buried there. Multiple entry points were provided [cf [START_REF] Hornecker | From Entry to Access -How shareability comes about[END_REF][START_REF] Rogers | Equal Opportunities: Do shareable interfaces promote more group participation than single users displays?[END_REF] so that individuals, in the context of a group activity, could make connections between their personal memories and in-the-moment experiences. Through these, an assortment of digital images, records, maps, sounds were 'at hand', that could be accessed, annotated, added to, and searched for, at different times and in different places. The resources, devices or displays were not owned by or given responsibility by any one person but were meant to be shared and used casually, and to be used to delve deeper into the details of a story.

We describe the technology set-up that was initially piloted in a small cemetery, and then used in events at a large cemetery. Then, we present a user study of it being used by various community groups. A follow-up interview study, a year later, was conducted to determine how they had engaged with it and what they remembered from using it. The findings are discussed in terms of what people recall about their experiences, how they reflect upon them, and what aspects of the technology they particularly remember.

Background

The use of computing technologies in museums has largely supported the solitary visitor, rather than the museum visit as a social occasion with people discussing and sharing their thoughts as they go around the exhibits. A popular aid is the mobile guide; visitors are given small handheld devices that are listened to like a mobile phone, sometimes with little screens. Whilst providing additional information for the individual experience they do not lend themselves to sharing, in the way written labels and other exhibit displays, like posters do. The audio guides typically provide background information about a painting or other artefact that is being viewed. They tend to be curated and hence do not support multiple perspectives, including that of the visitor [START_REF]The Handheld Museum[END_REF].

Social Interactions

The social aspect of visiting exhibitions has been explored in response to the realization that most visits to museums and other cultural places are in families or small groups [START_REF] Wakkary | Kurio: a Museum Guide for Families[END_REF]. Woodruffe [START_REF] Woodruff | Eavesdropping on Electronic Guidebooks: Observing Learning Resources in Shared Listening Environments[END_REF] designed an audio guide that could be shared, through an 'eavesdropping' mechanism, meaning that people could both listen to information, but also have conversations with each other and overhear other people's conversations. Social interaction is also the focus of the Kurio museum guide system, in which visitors were assigned the role of time travelers as part of a game, working as a team to collect various forms of information from the museum environment in order to repair their time traveller's map [START_REF] Wakkary | Kurio: a Museum Guide for Families[END_REF]. Kurio, a hybrid system, comprised a set of tangible computing devices, a PDA, and a tabletop display. Participants enjoyed working collaboratively and also enjoyed 'doing things' by pointing, gesturing, reading and listening with the various devices. Mcloughlin [21] developed a system to augment an open-air folk museum which aimed to recreate life from late 19 th century through a series of dwellings that people could walk up to and look inside. Visitors could meet the 'inhabitants' of these dwellings, who explained how they went about their household chores or carry out other jobs. An empirical study showed that when exploring the park, visitors tended to reminisce about their childhood and about memories of the past from parents and grandparents. The researchers, therefore, developed a sys-tem that centered around this theme of memories: visitors were able to listen to memories of historical figures and record their own in response, and through the collection of tangible tokens could listen to memories that had been left behind by other visitors [START_REF] Mcloughlin | Design Interventions for Open-Air Museums: Applying and Extending the Principles of "Assembly[END_REF]. Another angle on interaction between visitors was developed by Ciolfi in 'Retracing the Past' [START_REF] Ciolfi | Including Visitor Contributions in Cultural Heritage Installations: Designing for Participation[END_REF]. Here, a deliberate effort was made to keep upfront information about the objects to a minimum, in order to encourage discovery and exploration by visitors. As part of this exhibition, both a 'Study Room' and a 'Room of Opinion' were set up; visitors engaged through a number of interactive objects, including an 'Interactive Desk', to study the provenance of the objects, and an 'Interactive Radio' to listen to experiences of other visitors and record their own. All these approaches involve the active engagement of visitors, where they have the possibility to share memories, conversations, personal thoughts and ideas. This was found to lead to high levels of engagement with the artefacts on display.

The above are examples of technologies that have been specifically embedded in a cultural setting to encourage reflection and exploration, and involve artefacts or exhibits that are in some way special but not normally part of the visitor's day-to-day life. Here, we are concerned with how technology can be set up to encourage experiencing history in evocative ways that will be long lasting.

Lasting memories Turkle [START_REF] Turkle | What Makes an Object Evocative?[END_REF] writes about the process of reflecting with objects that are very much part of our normal life, but that are somehow 'evocative' to people. Such evocative objects often relate to 'thresholds', both widely experienced historical events (e.g., war), and important transitions and developments in our own lives. They often command a sense of provenance, being evocative because they are understood in relation to particular places and events. Through these characteristics, our experience of an evocative object often subverts the sense of distance between us, and another time and place. This creates further emotional and reflective responses that are important for personal development.

Another way of characterizing the relationship between the user experience and technology is in terms of enchantment. This refers to "a sense of something not yet understood in a way that leaves us feeling disrupted yet alive, attentive, and curious" [START_REF] Chonchúir | The Enchanting Potential of Technology: a Dialogical Case Study of Enchantment and the Internet[END_REF]. Bennet [START_REF] Bennett | The Enchantment of Modern Life: Attachments, Crossings and Ethics[END_REF] suggests it refers to how people get 'caught up and carried away', heightening their perception and attention, but often through a process of disorientation. McCarthy et al. [START_REF] Mccarthy | The Experience of Enchantment in Human-Computer Interaction[END_REF] propose that new technologies can be designed to enchant, and enable people "to wonder and to the wonder of life". Anecdotal examples include encountering the Apple G4 Powerbook for the first time. They argue that the more depth there is when making discoveries the longer the enchantment will last. Ross et al. [START_REF] Ross | A designerly critique on enchantment[END_REF] discuss how enchantment can be viewed in terms of meaningful mediation and the tensions surrounding them; for example, wearing an iPod changes the way we experience the world and the way we interact with people.

Journeys and Discovery The goal of our research is to design technology as an enabler to evoke experiences, triggering and cementing new associations with a place being visited. Ubiquitous computing offers much scope for facilitating and connecting past and present user experiences, through enabling people to 'dive in and step out' [c.f. 1], reflecting on their discoveries. Benford et al. [START_REF] Benford | From Interaction to Trajectories: Designing Coherent Journeys through User Experiences[END_REF] have developed the framework of trajectories to characterize user experiences as journeys through hybrid struc-tures, interrupted by transitions, and in which the interactivity and collaboration are orchestrated over space and time, involving multiple roles and interfaces [START_REF] Benford | From Interaction to Trajectories: Designing Coherent Journeys through User Experiences[END_REF][START_REF] Benford | Can You See Me Now? In[END_REF]. The orchestration of what the players have to do is pre-planned to instill certain forms of pleasure, learning and surprise. A question this raises is how much of the experience should be engineered for and how much should be left as ambiguous or uncertain. Should the user experience be scripted to a high level to ensure that participants are guaranteed a certain kind of experience [START_REF] Benford | Can You See Me Now? In[END_REF] or should it be left more open-ended, so that surprising and serendipitous experiences can result [START_REF] Chalmers | Seamful and Seamless Design in Ubiquitous Computing[END_REF]? The benefit of the former is that participants are reassured and know what they have to do, where to go and the objectives of the game. However, they may not discover much for or about themselves that makes them marvel or enables them to make deep and long-lasting connections. To enable people to take the initiative and discover new connections requires thinking about how to design for chance and serendipity [START_REF] De Bruijn | Serendipity within a ubiquitous computing environment: a case for opportunistic browsing[END_REF]. This, in turn, involves more than simply designing for fortunate accidents to happen. For example, Andre et al. [START_REF] André | Discovery Is Never By Chance: Designing for Un-Serendipity[END_REF] argue that it is important to design not just for the discovery of new information but also the insights drawn from those discoveries. These can be gleaned through discoveries that are not only serendipitous but also through the movement between different types of experiences, some of which are systematically reasoned about and others driven by curiosity [START_REF] Tieben | Curiosity and Interaction: Making people curious through interactive systems[END_REF].

Evocative Computing The focus of our research is how to design for more openended experiences, encouraging people to discover and make connections, themselves. Although they may be more disorienting and confusing than scripted ones, we argue they can lead to deeper and more memorable experiences. In particular, we are interested in enabling people to make connections with their own personal life, emotions, memories and thoughts while exploring cultural heritage sites as places of the past. We argue that such connections can lead to people gaining deeper insights into the historical context of the site in relation to their own lives, and in doing so making the experience of exploring the historical site a memorable one. Our approach, evocative computing, is intended to provide opportunities to support the creation of associations that can leave a lingering impression on an individual.

3

The Setting

The setting for our main study was an old Victorian cemetery -a cultural heritage site with a rich social history [START_REF] Curşeu | Alive after Death: An Exploratory cultural Artifact Analysis of the Merry Cemetery of Săpânţa[END_REF][START_REF] Dow | Exploring Spatial Narratives and Mixed Reality Experiences in Oakland Cemetery[END_REF]. When walking through the cemetery we may read the inscriptions on the headstones, wondering who the person was, how old were they when they died, what they died from, what kind of life they lived and who they were related to. When we come across a headstone that shows that someone died young, it can stop us in our tracks as we try to imagine what was the cause. To expand upon our notion of evocative computing, we ask: How can we move beyond the inscriptions to allow visitors to delve deeper [START_REF] Chonchúir | The Enchanting Potential of Technology: a Dialogical Case Study of Enchantment and the Internet[END_REF][START_REF] Mccarthy | Technology as Experience[END_REF], not only to make connections about the lives of the people buried there but also to what is present around them and to their own personal lives?

The cemetery (see Figure 1) is situated in a small city in the UK. There are around 20,000 burials in the cemetery, most in unmarked graves, with around 3,500 marked by headstones. Some of the headstones are very old, overgrown, and covered in lichen. The people buried there were from a variety of backgrounds and part of the pleasure of visiting the cemetery is to imagine and discover more about them.

Fig. 1. Headstones in the cemetery

The Evocative Technology Set-up

We assembled a number of interactive displays and mobile devices that were distributed indoors and outdoors for people to look at and interact with when in different locations. The technology was adapted from a previous project [START_REF] Coughlan | Enabling live dialogic and collaborative learning between field and indoor contexts[END_REF] for the specific context and challenges of the cemetery. The idea was to provide multiple perspectives when either in the cemetery or an adjoining building, in order to encourage diving in and stepping out [START_REF] Ackermann | Perspective-Taking and Object Construction: Two Keys to Learning[END_REF], and in so doing, enabling serendipitous associations. The set-up comprised smartphones, iPads, video links and a shared multi-touch surface. Interlinked software apps and access to digital databases were developed to run across them. A variety of lightweight interactions were made possible that only required minimal learning. A photograph could be taken, then annotated with some text, and linked with a grave on a digital map. It was considered important that interactions required minimal learning, to enable the participants to feel comfortable using them, with only a quick introduction. The iPads and smartphones were intended to be used outside -to take photos of headstones and other things of interest (see Figure 2). A room in an adjacent building to the cemetery was also set up as an indoor space for stepping back and reflecting on what had been seen in the cemetery. The technology comprised a Surface Tabletop computer mirrored onto the wall, laptops and a screen displaying a live stream from the site. A phone was provided for discussions with those outside (see Figure 3).

The photos that were taken by people outside could be uploaded in real time to appear on an interactive bird's eye view map of the cemetery displayed on the tabletop (see Figure 4). When indoors, participants were able to see photos being added onto the tabletop view of the graves -initially appearing in the form of coloured dots. Touching a dot resulted in bringing up the image taken there, and any information connected by the participants. The smartphones also allowed for texting and phone calls to be made between those inside and those outside in order to exchange information and generally plan the activity between group members. Live video images from a camera outside were shown on a wall display indoors, providing those indoors with a live roaming feed for allowing them to see what those outdoors were doing. which could be accessed from a wide range of devices to allow data to be up loaded and referred to from multiple locations. Accounts of the grave inscriptions and other parish records or copies of old newspaper clippings could be accessed. Other publicly available sources of information online, for example the digital records from the Commonwealth War Graves Commission, could also be accessed. The photos taken outdoors and the digital records were geo-referenced and mapped within the visualizations for the different devices. The GPS locations of the groups outdoors were automatically sent to a web server once every minute by the mobile phones. This location data was then displayed on the tabletop as part of the visualization. This enabled those indoors to see where the groups were outside as they moved around the cemetery. They could also see each photo they had collected, where they had collected it and any information each team had attached to that geo-referenced image.

The Design Process

Several visits to the cemetery were made with numerous meetings held with representatives from groups who are interested in and/or use the cemetery. One group of local volunteers was the Friends of the Cemetery who work together with the Parochial Burial Grounds Management Committee and the City's Council to protect and enhance the cemetery for the public benefit. They view the cemetery as a special type of green space -a place of remembrance, spirituality, history and wildlife. An initial prototype was trialled in a smaller graveyard to see how easy it was to use and switch between the various tools and displays. We invited the Friends of the Cemetery to trial the prototype set-up. Small groups of 2-3 participants went outside, took photos of interesting sightings and added notes. Each group then came inside and were shown the data they had collected, overlaid on the bird's eye view of the graveyard. A strong 'wow' reaction was observed; as groups experienced, for the first time, the transition from taking photos outside to seeing them linked with where they had taken them on a large-scale map. They were very moved by seeing their personal photos now as digital dots of where they had been (Figure 4). Clicking on them elicited spontaneous conversations about what they had seen, imagined and done there.

4

User Study

The user study was run in two parts. The first part took place over a period of 4 weeks during which four sessions were held, each with 12 to 22 participants visiting the cemetery. The second part took place a year later, when we revisited participants and interviewed them about their experiences and memories. Leaving aside the group who focused on wild-life, we report here on how two groups that already made visits to the cemetery for different reasons, had their visits enhanced through the technology:

(i) School children A group of 22 children, aged 14 to 15, who were studying drama, took part. Their drama teacher had used the cemetery before in her courses as a source of inspiration for writing and performing plays about people, although not yet with this particular group of children.

(ii) Local volunteers A group of 20 adults, who had a strong interest in local history, and, in particular, how stories involving the people who are buried in the cemetery inform us of the past took part. They had been working for some time on ways to digitally map the graves and on collecting materials.

Activity design We considered it important to let the teacher and the person running the local volunteer group decide on the focus of their explorations, in order to give them autonomy over what they wanted to engage with in the setting so as to fit in with their own interests and activities [START_REF] Giaccardi | Reframing Heritage in a Participatory Culture[END_REF]. Our role was to provide technology to evoke and connect with personal experiences and help people explore and discover for themselves. The teacher chose to develop her class around the cemetery where the pupils had to create a play about the experience of soldiers in WWI and to contrast this with more recent wars, such as the Gulf War. The cemetery has a number of WWI graves of soldiers who died serving during this war, which are located throughout the cemetery.

The local volunteers wanted to identify graves in a particular part of the cemetery. Some twenty years earlier another history group had compiled lists with details of the inscriptions on each grave. This information had been transformed into database records, but no photographs were included nor was it clear where precisely each grave was located. They wanted now to determine the location of each grave and mark them on a large aerial photograph of the cemetery as part of their local history project.

The sessions At the beginning of each session an initial demonstration of the devices was given. The large groups were then broken up into smaller groups of 3-4 and left to work under the guidance of their leader/teacher. Participants were encouraged to make use of both the indoor room and the cemetery, which were only a few minutes walk from each other, enabling the smaller groups to visit both in a staggered way. Each session lasted between 1.5 to two hours.

The children began by looking at the headstones to see who might have died during WWI, and photographing them. One group remained indoors, researching background information on families, regiments and war locations. Throughout the afternoon groups around to enable all to switch between being indoors and outdoors. The volunteers in the cemetery started by photographing graves and then used the iPads to look up records in an attempt to link them together. They also interacted with the map on the tabletop indoors and guided the others outdoors on missing information. We used a mix of methods in order to study how the participants made use of the devices, how they approached their activities and what it was they talked about to each other. All the interactions with the technology were recorded using still photographs, video and notes. A team of researchers roamed around the cemetery observing the groups, and chatting to them informally (see Figure 5). Whenever groups moved from the outdoor to the indoor area, or vice versa, they were accompanied by one of the researchers, during which they would talk informally about what they had been doing and found. At the end of each session participants were asked to share their thoughts and impressions through a feedback form. We also held a group discussion with the teacher and children to talk about their findings and experiences.

A year later we went back to talk to the children, the teacher and the volunteers who were available. We asked them about their experiences of walking around the cemetery, using the technologies, conversations they had and whether anything had followed on from it. We spent a day at the school where the school children had now completed their drama coursework. We read the monologues they had written and also met with the next cohort of children who were just starting out on their drama course and listened to how they approached the task.

The data collected was analyzed thematically. These were refined and verified by a comparison of themes produced across the research team. The focus of our analysis was on how the participants made discoveries, in situ, in particular, how they used the devices and displays to make connections between their own lives and the histories of the lives they were discovering.

Findings

Our analysis revealed observable moments where participants discussed their 'personal evocative memories' with each other. We also observed 'digital situated awareness' of where they were and what they had just done. Below we present our findings in terms of a set of themes related to evocation and memory: (i) digital delight of being there, (ii) revealing more, (iii) serendipitous discovery, (iv) triggering and extending the personal, (v) personal memories and making connections, and (vi) seeing things differently.

Digital delight of being there Similar to the finding of the pilot study discussed earlier, key moments that occurred within both the school children's and the volunteers' sessions were, when after being outside taking photos, they came inside and were struck by seeing a representation of their own collected data on the big display on the wall or the tabletop. Many experienced a sense of delight on seeing the 'dots grow'; representing their photographs and where they were positioned on the map of the cemetery in real time at the place they had taken them. This indoor-outdoor set-up provided them with a new way of seeing their photos transformed into a collection of shared representations on a map, showing their discoveries. They looked at the map as more dots appeared, seeing what photos the others outside were adding. In doing so, they vicariously understood the process of being out there taking a photo while seeing it become a collective data point. This shared awareness gave them a powerful sense of connection -being present and stepping back, enabling them both to remember the details surrounding taking the photo and to reflect upon the bigger picture. Evidence of their joy and wonderment at this was made through their comments to each other and the researchers standing by. For example, 'Hey look at that! That's the one we took, remember? When we were near that bench. …' and from the organizer of the volunteers:

'this is amazing … there's been so much activity this afternoon, we've made so much progress, so many photos taken, and you can see all the activity on the map…..'

The groups were also able to see at a glance how many photos they had taken relative to the other groups -which was particularly fascinating to the school children as they were seen discussing this with their teacher. It also led them to get in touch with the other groups outside, texting them to say how well each group was doing and what photos they were taking.

Revealing more One of the volunteer groups tried to fathom out which inscription entry in the database matched with which grave, and where each grave was located. Another group was seen spending a lot of time around a particular grave trying to decipher its inscriptions. The stones were covered with a layer of lichen, a soft mossy type of fungus, making it particularly difficult to discern the writing. They were seen feeling the stone, with their fingers, to make sense of the engravings. Later on, the same group was seen using the tabletop indoors. They were looking at the photograph they had taken of the gravestone that was so difficult to decipher. By zooming in on the photograph, and enlarging it, they noticed that it was easier to decipher some of the lettering, exclaiming how the zooming action on the tabletop enabled 'magnification of the picture' that resulted in further conversations about the person buried there. This was a very pleasing moment for the group as the tabletop was able to support them in an activity that was causing them difficulty outdoors and showed a use of the tabletop that they had not anticipated. The moment was powerful, particularly since they had only just come from outside, having spent considerable amount of time around the gravestone. While outside, they had used both the iPad and the smartphone to try and identify the gravestone, but it wasn't until they were inside, that they managed to successfully do so.

Serendipitous discovery Whilst looking at the map of the cemetery, one of the participants accidentally pressed a dot on the map, which was associated with a different grave, near to the one they had just identified. This brought up the associated description of a famous local historian, John Seeley, who was buried there. Another volunteer (who was also a historian by profession) glanced at the description, read it and jumped up in amazement: 'Seeley… Is that really him??' 'Seeley … he's a really really great man! Professor John Seeley … he's the big researcher into the British Empire.' He continued to explain how university buildings in the locality are named after him and regaled stories of Seeley's infamous dinner parties and what happened at them. He then looked at the tabletop to find out exactly where this grave was in relation to the others on the map. All of the group were drawn in by his anecdotes and stood around the tabletop discussing where the grave might be through studying the pattern of dots. It transpired that the grave was right next to where he had been exploring all day but hadn't noticed the gravestone until this moment: 'I'll have to go back and find him now. Well that's amazing -not quite like finding Shakespeare but… yes, it's on the same scale. Heavens, as it happens, I'm actually teaching about him right now.' He then left the room to go back to the cemetery and found the grave. His excitement at finding it was palpable and after spending 20 minutes out there returned to tell everyone about his discovery.

Triggering and extending the personal A year later, we met up with him and asked if he had looked back on that afternoon's discovery. He replied emphatically that finding that grave had been a special moment for him. He had referred to it on several occasions during his lectures and at international conferences. He also reflected more widely on the value of local buildings and graveyards and their potential for teaching history to students through situated discovery:

'For many years I have had something brewing at the back of my mind, about trying to do something like this in teaching. Taking students out to places, local building, and letting them do research about people that lived and worked in the area. For me these ideas sit at the back of my mind for a while. I get an idea and it all gets put into a store, perhaps for many years, slowly taking shape. And then something like this happens …' Hence, finding the particular grave had triggered something greater in him, as he was now actively reorganizing his teaching schedule so that his students would have more opportunities to go out to visit the local cemetery. His new approach to teaching had been evoked through the powerful moment in the cemetery.

The dots in the visualization appeared to have had a strong impact in this experience. It was he who brought up the role of the digital map application and it was clear that he could still imagine the visualization in front of him. He mentioned how he had expected the dots on the map to present an anonymous image of the cemetery: expecting each dot to represent some facts about an unknown, local, rather insignificant person. However, to his surprise, one of the dots sprung up the details of a person who was, and still is, of great importance to him personally, someone who had been tremendously influential to him throughout his whole working life. Despite all he already knew about the person, the technology had supported a new, evocative experience and with lasting effects.

Personal memories and making connections As anticipated, the school children, when wandering around a part of the cemetery used the iPads to help them find out more about the war graves. Sometimes this led them to think back on their own family histories. For example, one group found two graves that matched with names on a list, photographed them and then uploaded them to the system. Another group indoors confirmed that they were on the right track. They then stumbled across a big family grave, with a long list of names and dates, including one for 1917. This grave was made of crumbly stone and the inscription revealed that the soldier died abroad in 1917. While photographing this grave, one boy began to talk of his grandfather and that he had served in the Balkans during WW2. This sharing of a personal memory triggered a further discussion of war amongst the group, and in particular the different countries that were involved in the two wars.

Throughout the day, there were several accounts of where the school children switched between everyday moments, personal memories and their drama project research. In addition, their experiences were embedded in the goings on around them (e.g., stroking a dog, chatting with homeless people sitting on a bench). The combination of these with their discoveries when switching between the cemetery and the setup indoors made a big impression, creating an overall engaging and memorable 'time'. The situated experiences, arguably, increased the intensity and recollection of them as subsequent personal memories. Such memories were often emotive, heightened by the context of death and according to the teacher, a few weeks after the event, the visit to the cemetery was still being talked about frequently amongst the school children in the classroom, in the corridors and even at home. When we met the children a year later, they were eager to tell us about the monologues they had written and about the characters they had chosen as a result of the visit to the cemetery. They were also reflective and mentioned how they had made connections between the war, the visit to the cemetery and their own families: "I talked to members of my family about the people -about their experience of knowing and losing -a person in the war." "In the summer, when I was in Germany, I spent more time in a graveyard there. In the village graveyard, where both my grandparents and my great-grandparents are buried. I visited graves and looked at them. In Germany, because of the way they do graves, like, they have different rules. There wasn't any war people buried there. But that's to do with their traditions. But it was just, I know, it was just different."

Exploring a cemetery during the vacation was not a regularly occurring activity for him -in fact he had never looked at these family graves before. Clearly it linked to the earlier experience of walking around the cemetery with his school friends the previous year. The personal memories of his grandfather then had helped him make connections between himself in the graveyard, with his friends, and the war and the countries that were involved in the war -but he was now extending this experience, by following it up with explorations of his own family.

Seeing things differently Several times, throughout their explorations of the cemetery, the school children reflected upon what they noticed and looked up using the iPads and tabletop apps. For example, one group when switching indoors after exploring outdoors looked up background information of the regiments. During the group discussion one boy remarked: "It is odd -that when you are in the cemetery, you only think of the person's death -where they died, when and how they died -and yet, when you are here (inside) and look into it more, you think of their life".

Having the same information -a soldier's name -can be used through multiple representations: inscribed on a gravestone, listed as a digital record, or as part of a description of a regiment and its action during war. These multiple representations allowed participants to look through different lenses at the same person, often having a powerful evocative effect.

During our discussion with the school children a year later it was noticeable that they did not specifically refer back to the technology they had used (phones, iPads and interactive tabletop), suggesting it was largely transparent to their ongoing activities. The exception, however, was the dots visualization on the tabletop, which continued to stand out: "What was so startling was that you go out to find out about a world event -a world war -which is a large international event, where countries are fighting.

War is about big numbers, about stats. (…) -when you're in the cemetery you see the graves -well, you saw the dots on the map -you see the scale of it. It's a big scale."

The teacher remembered how the activity greatly impacted on her drama course: "These were remarkably reflective pieces that this group wrote. They were very thoughtful. They really went into the characters and I am really pleased with what they produced." For her, like the historian who had changed his approach to teaching, the experience had led her to reflect on her teaching: "It is also exactly how I think they should research (site specific), hands on, out there learning" and "Whereas before, I would have encouraged pupils to make lots of notes when visiting places, to help them start preparing for their narratives -I now tell them to bring their phones to school, so that they can make photos of the things that strike them as special or unusual, in order to be able to remember where they were."

When meeting again with some of the local volunteers, they talked purposefully about their experiences of locating and identifying the graves in the cemetery. Underlying their concerns about data collecting and how to store data, there was a sense that the sessions in the cemetery had helped cement friendships across the group -they looked back on the sessions with great fondness, recalling moments, and people and who had said what when.

Discussion and Conclusion

Our study has shown how an assortment of technology can be designed and used in a historical setting by groups of visitors to discover much more about the lives and social history of people buried in a cemetery that they were able to relate to their own personal histories. Moreover, the experiences were found to be long lasting; through using the devices and displays distributed indoors and outdoors, the participants made a variety of connections between their own lives and the lives of the people they were exploring that one year later, they were still talking about. Our research raises the question of how do memories created through the evocative computing approach differ from those arising from just visiting a cemetery or other place of interest/historical site, without the range of technologies we assembled, and perhaps only having a mobile phone to hand. Clearly, it is possible to connect personal memories with the surroundings of an ongoing activity unaided by technology and to take pictures that can be looked at later. What role did the technology play in making the experiences so engaging and memorable? Below, we discuss possible ways our evocative computing approach enriched the user experience.

(i) Multiple and memorable representations A technology that played a central role in the linking of discoveries and personal experiences was the tabletop visualization, where the dots appeared in real-time representing pictures taken and information recorded. The participants were able to see the dots as something other than places on a map where photos were taken; more akin to a synecdoche between their discoveries, activities and memories: when, where and what the photos they had taken meant to them. The dots were the most remembered part of the technology set-up when talking about the experience a year later. They acted like a memory cue, similar to Mancini et al's [START_REF] Mancini | From spaces to places: Emerging contexts in mobile privacy[END_REF] idea of a memory phrase, which enables people to go back to the memory of particular events and retrieve salient and emotive aspects of their experience in detail. Whereas Mancini et al deliberately asked people to make up a memory phrase in their study, asking people to remember what they were doing at various times of the day for a project on mobile privacy, the 'line of dots' emerged serendipitously for our participants. For example, for one boy, the dots led him to marvel that worldwide events were happening on his doorstep: "you think of WW2 and you know it's big stats, but then it is happening in my locality, that struck me -it's here". For a volunteer, it was the epiphany of the unexpected: he had expected the dots to represent local people, with local issues and local stories -and instead discovered that the grave of a revered historian was on his doorstep.

(ii) Intertwining place, information and narrative The findings from our study show how the volunteers began to understand how the role of technology is not just about placing documents and photos in databases and archives, but that it can also support their physical interactions with aspects of the cemetery, and each other.

(iii) Connecting personally meaningful, local and global Research in HCI on memories and cultural heritage, historical events and places has tended to be separate. The connections between these are rarely made, and often local places, close by and with the potential to be exceptionally evocative, are ignored thus giving little importance to people's autonomous engagement with cultural heritage in the context of their own lives and the specific settings of where they live [START_REF] Giaccardi | Reframing Heritage in a Participatory Culture[END_REF]. Here, we demonstrated how strong links can be seen between them. For example, the school children realized how the cemetery could trigger personal memories that made war history more meaningful and closer to home.

Our findings suggest, more generally, that the evocative computing approach can lead to meaningful and lasting experiences. It provides a way of thinking about how to enable visits to digital heritage sites, such as castles or ruins, to be enhanced not just during them, but also to create long lasting memories in a person's life. Specifically, by having multiple connected technologies at hand, different entry points for serendipitous experiences are made possible. The kinds of 'wow' moments we recounted may not always arise -but that is the essence of designing for serendipity. You cannot design directly for but you can provide opportunities. As our study revealed, participants readily switched between these entry points, uncovering information as and when they wanted -thus revealing the hidden which they could make into new persistent connections. Evocative computing works as an approach to support open-ended and user-created trajectories across space and time -that is different from trajectories or tasks designed and orchestrated by others (e.g. teachers, curators, designers).

In sum, the technology can act as a kind of glue enabling people to make connections between different aspects of their experiences later on. This suggests that when designing user experiences we should consider a range of temporal aspects, not just the immediate experiences of using technologies but also what the long lasting impact will be of interacting with them. Hence, an evocative computing approach should consider providing conditions rather than pre-defining expected outcomes. Finally, technology has often been designed to enhance specific experiences taking place at specific moments. Often the joy, wonderment and pleasure of an event are assumed to occur if people simply interact with an experience. However, our research has shown the value of enriching a personal and emotive moment through technology that then makes this a lasting, meaningful experience.

Fig. 2 .Fig. 3 .

 23 Fig. 2. Using mobile devices to look up database records and to photograph the graves

Fig. 4 .

 4 Fig. 4. Two pairs of students collaborating around the tabletop and laptops (left) and bird's eye view of the cemetery on the tabletop with dots representing the graves (right)

Fig. 5 .

 5 Fig. 5. School children showing their photos and describing their discoveries to a researcher in the cemetery

Acknowledgements

We thank the Parochial Burial Grounds Management Committee for their permission to use the cemetery and Anglia Ruskin University for use of their premises. We also thank Sarah Tovell (Cambridge City Council) and Kay Blayney and pupils (Parkside Federation Academies) and the Friends of the Mill Road Cemetery for their enthusiastic engagement with the project. Many more people helped to make this project possible, including Margaret Widdess, Fabrizio Manco, Seán Lang, Victoria Smith, Simon Ruffle, Canan Blake and John Lea. The research was funded by the EPSRC OTIH project (EP/H022589/1). Estefanía Martín and Pablo A. Haya acknowledge the ASIES (TIN2010-17344) project, from the Spanish Ministry of Science and Innovation that partially funded their participation.


Shun'ichi Tano

Shinya Yamamoto

Junko Ichino

Tomonori Hashiyama

Mitsuru Iwata

Truly Useful 3D Drawing System for Professional Designer by "Life-sized and Operable" Feature and New Interaction

Keywords: 3D Sketch, Life-size, Operability, Professional Designer, Mixed reality

Media" is an artifact that expands our creativity and intelligence. We have been studying the use of "Rich Media" to support creative and intelligent human activities. Specifically, for over ten years we have focused on the 3D space as one of "Rich Media" and developed many 3D sketch systems that support the design of 3D objects. However, their long-term evaluation has revealed that they are not used by designers in real fields. Even worse, they are treated as if they were just mere attractions in an amusement park. The fundamental problem is the lack of the indispensable function for 3D space. In this paper, we propose new design principles, "life-size and operability", which make the 3D sketch system truly valuable for the designer. The new 3D sketch system is designed on the basis of "life-size and operability", developed, and evaluated successfully.

Introduction

"Media" is an artifact that expands our creativity and intelligence. The oldest media is words and numbers. The computer is now widely used as a media.

We have been studying a wide range of creativity-centered media to ensure that systems truly support creative and intelligent human activities. They range from those used by knowledge workers to those for car-exterior designers [START_REF] Dzulkhiflee | Effectiveness of Annotating by Hand for non-Alphabetical Languages[END_REF][START_REF] Iwata | A Sketch Support System Based on Behavior of Designers[END_REF][START_REF] Ichino | Support for seamless linkage between lessdetailed and more-detailed representations for comic design[END_REF][START_REF] Tano | Digital Paper Concept for Reflective Writing by Seamless Traverse between Handwritten and Coded Information[END_REF][START_REF] Tano | Quantitative Study on the Effectiveness of Pen-based Computing on Experiential and Reflective Cognitive Modes[END_REF][START_REF] Tano | Godzilla: Seamless 2D and 3D Sketch Environment for Reflective and Creative Design Work[END_REF][START_REF] Tano | Extended Godzilla: Free-form 3D-object Design by Sketching and Modifying Seven Primitives at Single 2D-3D Seamless Display[END_REF][START_REF] Tano | Natural Hand Writing in Unstable 3D space with Artificial Surface[END_REF][START_REF] Tano | Quantitative Analysis of Human Behavior and Implied User Interface in 3D Sketching[END_REF].

Specifically, for over ten years we have developed many 3D sketch systems that support the design of 3D objects, because the 3D sketch cannot be realized without the power of advanced information communication technology (ICT) [START_REF] Tano | Godzilla: Seamless 2D and 3D Sketch Environment for Reflective and Creative Design Work[END_REF][START_REF] Tano | Extended Godzilla: Free-form 3D-object Design by Sketching and Modifying Seven Primitives at Single 2D-3D Seamless Display[END_REF][START_REF] Tano | Natural Hand Writing in Unstable 3D space with Artificial Surface[END_REF][START_REF] Tano | Quantitative Analysis of Human Behavior and Implied User Interface in 3D Sketching[END_REF]. We regarded the 3D sketch as the drastic extension of the traditional "pen and paper" media made possible by the power of ICT.

However, long-term evaluation has revealed that 3D sketches are not used by designers in real fields. Even worse, they are treated as if they were just mere attractions in an amusement park.

It shows that the rich media certainly fascinates the ordinary users but is ignored by the professional users in some cases. It may be the serious problem because there are many systems that blindly utilize the rich multimedia without the long-term user evaluation [START_REF] Tano | Three Design Principles Learned through Developing a Series of 3D Sketch Systems: "Memory Capacity[END_REF].

In this paper, we analyze the fundamental problems that prevent the systems from being used professionally. We point out that it is the lack of the indispensable function for 3D space. Then we propose a new design concept inspired by "mixed reality", that makes the 3D sketch system truly valuable for the designer, and exemplify the feasibility of the new design concept by describing our latest prototype system.

2

Related Works and Purpose

Related works

Conventional research into 3D sketching can be categorized into two types. The first is generating 3D sketches from 2D sketches [START_REF] Shin | Magic canvas: interactive design of a 3-D scene prototype from freehand sketches[END_REF][START_REF] Olsen | Stroke extraction and classification for mesh inflation[END_REF]. The designer draws a 2D sketch, then the system converts it into a 3D sketch on the basis of certain assumptions, and finally the system displays it in a 3D space.

The second is drawing the 3D sketch directly in midair [START_REF] Wayne | Interactive Augmented Reality Techniques for Construction at a Distance of 3D Geometry[END_REF][START_REF] Steven | Surface Drawing: Creating Organic 3D Shapes with the Hand and Tangible Tools[END_REF][START_REF] Gerols | Free Drawer: A Free-Form Sketching System on the Responsive Workbench[END_REF][START_REF] Daniel | A Fully Immersive 3D Artistic Medium and Interactive Experience[END_REF][START_REF] Tovi | Creating Principal 3D Curves with Digital Tape Drawing[END_REF][START_REF] Perkunder | Shape modeling with sketched feature lines in immersive 3D environments[END_REF]. The 3D lines are displayed as they are or as transformed smooth lines and converted into the model description in some systems [START_REF] Tovi | Creating Principal 3D Curves with Digital Tape Drawing[END_REF][START_REF] Perkunder | Shape modeling with sketched feature lines in immersive 3D environments[END_REF].

We have also developed a series of 3D sketch systems [START_REF] Tano | Godzilla: Seamless 2D and 3D Sketch Environment for Reflective and Creative Design Work[END_REF][START_REF] Tano | Extended Godzilla: Free-form 3D-object Design by Sketching and Modifying Seven Primitives at Single 2D-3D Seamless Display[END_REF][START_REF] Tano | Natural Hand Writing in Unstable 3D space with Artificial Surface[END_REF][START_REF] Tano | Quantitative Analysis of Human Behavior and Implied User Interface in 3D Sketching[END_REF] in both categories mentioned above.

Although each system has its own strength and has been successfully evaluated by the designers, the common problem is that they are not utilized continuously by professional designers in daily design tasks over long periods of time. They are missing something that would make them indispensable for professional use.

Purpose of this paper

In this paper, first the role of 3D space is categorized into two types: "draw in 3D space" and "view in 3D space". Second, our four trial systems are briefly shown as examples that support all roles of 3D space.

Third, the long-term evaluation of the four trial systems is summarized. It shows that the fundamental problem is the lack of indispensable functions for 3D space.

Fourth, we propose new design principles "life-size and operability", which make the 3D sketch system truly valuable for the professional designer.

Finally, our latest 3D sketch system designed by the new design principle is explained in detail and evaluated by professional designers.

Our Trials for 3D Sketch System

We have developed a series of 3D sketch systems. The following subsection describes four typical systems [START_REF] Tano | Godzilla: Seamless 2D and 3D Sketch Environment for Reflective and Creative Design Work[END_REF][START_REF] Tano | Extended Godzilla: Free-form 3D-object Design by Sketching and Modifying Seven Primitives at Single 2D-3D Seamless Display[END_REF][START_REF] Tano | Natural Hand Writing in Unstable 3D space with Artificial Surface[END_REF][START_REF] Tano | Quantitative Analysis of Human Behavior and Implied User Interface in 3D Sketching[END_REF] (called Systems 1, 2, 3 and 4).

Role of 3D Space

2D/3D space can be used in two ways as shown in Fig. 1. The first is the space where the designer draws the objects. To draw in 3D space means to draw objects in the 3D space directly, i.e., for designers to sketch them in midair in front of themselves. To draw in 2D space means to draw objects in the 2D space, i.e., using a pen and paper.

The second one is the space where the designer looks at the objects. To view in 3D space means designers look at objects in midair in front of them (stereovision). To view in 2D space means to look at objects as perspective 2D images on the 2D plane. Fig. 1. "Draw in 2D/3D space" and "view in 2D/3D space". Systems 1 and 2 support the 2D-draw and 2D/3D-view. The designer draws a 2D sketch and views it both in stereovision in the 3D space and as a perspective 2D image on the 2D plane. The reason the systems do not support 3D-draw is the difficulty of drawing in a 3D space directly.

Systems 3 and 4 have a mechanism to compensate for this difficulty, so they support the 3D-draw and 3D-view.

3.2

Our 3D system-1: "Godzilla" System 1, called "Godzilla", aims to support creative design, specifically that of carexterior designers.

Design Flow

Fig. 2 shows the typical design flow. First, the designer draws the concept image on the 2D pad (a tablet with an LCD) as shown in Fig. 3(a). The designer can grasp the sketch and hold it in midair, and it appears as a 3D image on the 3D pad (stereovision TV) as shown in Fig. 3(b). While holding and rotating the 3D-image, the designer can look at it from different viewpoints. When the designer grasps the image and puts it onto the 2D pad, it appears on the 2D pad as a 2D sketch. Note that our system displays a hand-drawn sketch all the time, even in the 3D space, and can automatically recognize the 3D shape of a 2D image and transform between the 2D and 3D sketches with different viewpoints while preserving the designer's pen touch.

Prototype System

Fig. 4 is a photo of the Godzilla system. Fig. 5 shows examples of car design using Godzilla. Note that a 3D image is displayed in midair just in front of the 3D-pad.

After we developed the Godzilla system, we took it to the design division of the Toyota automobile company for the initial evaluation.

Our 3D system-2: "Extended Godzilla"

Godzilla has problems: [START_REF] Dzulkhiflee | Effectiveness of Annotating by Hand for non-Alphabetical Languages[END_REF] The range of forms it can handle is restricted to car-like forms, and (2) separate 2D and 3D monitors feel unnatural.

Free Form Design Using a Combination of Seven Primitives

It is obviously impossible to recognize a 2D sketch of a 3D form without any knowledge of the sketched form since a 2D sketch cannot retain all of the shape information. To enable free-form design, we developed a design approach that enables the designer to draw primitive forms and then combine and modify them.

Our system has seven primitives: triangular pyramid, square pyramid, triangular prism, square prism, cone, cylinder, and sphere. A typical design flow is shown in Fig. 6. First, the designer sketches the primitive shapes, and the system recognizes them. The designer then combines and modifies the primitives or views and checks the shapes in the 3D space.

Natural Seamless 2D-3D Display

To provide a natural display, the display unit has to support the seamless 2D-3D transition. To meet these requirements, we used an LCD monitor with polarized light screens (a "micro-pole filter") and polarized glass (see Fig. 7). The only operation in 2D-3D space is "pull and push." As shown in Fig. 8, when the designer "pulls" an image in the 2D space, the image is gradually raised from the surface of the LCD. Conversely, when the designer "pushes" an image in the 3D space, the image gradually sinks into the LCD. Representative sketches are shown in Fig. 9. Note that the images can be viewed from any angle since the sketches have a 3D structure.

Our 3D system 3: Rich Visual Feedback

Sketching in 3D space is difficult, particularly because the senses of depth and balance are poor. This indicates that a user interface is needed to compensate for the difficulties.

For the compensation, the interface needs to enhance the user's awareness of errors.

We found that using the metaphors of "shadow" and "hand mirror" effectively achieves this, as illustrated in Fig. 10. Note that the shadow and mirror are also 3D images.

3.5

Our 3D system-4: Force Feedback System 4 tried to solve the same problem as System 3 by providing the designer with the virtual force field (virtual surface) in midair.

Approach

We devised four types of force field to cope with the problem. They are characterized in Fig. 11.

(a) Uniform force field: The uniform inertia is produced in the drawing area. The designers feel as if they were drawing in jelly.

(b) Automatic generation of surface: The artificial surface is automatically generated in accordance with the drawing. When many lines are judged on the same plain, the force field is automatically generated to shape the plain.

(c) User-defined surface: The user can indicate the needed surface by gesturing. (d) Use of 3D rulers: We designed several virtual 3D rulers, which include the virtual sphere, the virtual rod with ditch (for drawing the straight line in 3D), the virtual 3D French curve, and so on. They are virtual in the sense that they are not real objects. The surface is artificially generated at the position of 3D sensor, so they are easily fixed in 3D.

Prototype System

We have developed a prototype system (Fig. 12). The user has a 3D-sensor (for a virtual 3D-ruler) in his/her left hand and an arm of the Phantom (the force feedback device) in his/her right hand for drawing in 3D. Fig. 13 shows the automatic generation of the surface. Note that it is seen in double since the left-eye and right-eye images are displayed. Long-term Evaluation

Short-term evaluation was promising

For each system, we conducted a short-term user test that showed our user interface was promising. All designers welcomed the novel interaction.

Long-term evaluation: 3D space is useless

However, they stop using the 3D space after a while. In the following subsection, the reason for this is analyzed in terms of "view in 3D" and "draw in 3D".

Analysis on "view in 3D"

While using Godzilla (System 1), the users draw a 2D sketch and lift it up into midair.

Then the 3D sketch is displayed, fascinating the users. Sometimes the user is surprised at the function. Nevertheless, sooner or later, they notice that they do not need to look at it in the 3D space as a 3D sketch. They can look at it on the 2D-pad and can rotate it in a similar manner. The difference is whether they are displayed in 3D (stereoscopic) or in semi-3D on the 2D plane (perspective 2D image). The same phenomena were also found while using Extended Godzilla (System 2). The users draw a 2D sketch and lift it up into midair gradually. Because the sketch seamlessly transitions from 2D to 3D, it surprises and fascinates all users. However, after a while, they bore of the seamless 2D-3D transition.

Analysis on drawing in 3D

While using System 3, the designer can draw a beautiful 3D flower image directly as shown in Fig. 10 by utilizing the effect of visual feedback. Also, while using System 4, a designer can draw a image stably by utilizing the effect of the virtual surface in midair. However, even though the designer is assisted by the visual feedback and the force feedback, 2D drawing is much easier than 3D drawing. Therefore, the designers tend to move to System 2 ("Extended Godzilla") as long as System 2 can handle the target image, so eventually they use 2D draw and 2D view as mentioned above.

Lack of indispensability of 3D space

Essentially, the 3D space is not for a designer in terms of either "view in 3D" and "draw in 3D". The reason designers stop using the 3D space is that they can do their work without it. In other words, our systems do not provide the designers with an indispensable function that truly needs 3D space.

New Design Concept

As long as an indispensable function of 3D space is not found, it is pointless to develop a support system that uses 3D space. Therefore, we stopped our research into 3D space for a few years. Recently, we found indispensable functions and restarted the research activity. Here, the latest findings and the current prototype system are shown.

Indispensable functions of 3D space

We found two indispensable functions that need the 3D space. The first one is a lifesized 3D sketch. If the 3D sketch is life-sized, the user evaluates the size to compare their own body and the 3D sketch shown in the midair in front of the user.

If the "life-sized" nature is missing, the users cannot evaluate it on the basis of comparison with their body, so the necessity of 3D sketch is lost.

The second one is a 3D sketch that must be operable by the user. The user should be able to operate the 3D sketch, that is, touch, push, move, and so on. If the 3D sketch is operable, the user evaluates the ease of use by operating while stooping down, extending a hand, or twisting his/her body.

Design concept "Life-sized and operable"

The 3D sketches must have a "life-sized and operable" nature. Since the life-sized 3D sketch can be evaluated by comparison with a user's body, it needs to be displayed in a 3D space in front of the user. For example, the user can notice that the table of this kitchen is low or the emergency button is far from the operator's chair. Similarly, since users can evaluate the operational 3D sketch by moving their bodies while operating, it needs to be displayed in a 3D space in front of the users. For example, the user can notice when operating a lever that the warning lamp is hard to see or the tray of the copy machine is too low to remove the paper jam.

6

New 3D Sketch System with Mixed Reality

New Design Flow

Fig. 14 shows the new design process extended by the new principle. The design flow is explained briefly by using the copy machine design example (see also Fig. 15).

Fig. 14. New design process.

In the first step, the designer is thinking of a shape of a copy machine, asking him or herself, "What's a smart design for a copy machine?" while drawing the idea in life-size and ubiquitously.

Second, the designer is thinking of the operation of the sketch, thinking to him or herself, "The tray will move in this direction. If I push this button, the paper is ejected.", then formulating the operation rules by grasping and moving the sketch shown in 3D.

Third, the designer checks the usability by operating the sketch while sitting down, stooping down, extending an arm, and so on.

Then the designer may find that a button is hard to push because it is inconveniently located, the tray is hard to pull out because you have to get into an uncomfortable position, and so on. The designer simply erases the 3D sketch and redraws it. Let's operate this copy machine!

Examples of Design Process

Fig. 16 shows our other application field, i.e., the control room design. It is very important to design a usable control room from the safety point of view. It is impossible to make a mock-up system due to the exorbitant costs. In a real design department, the designers will design it virtually by using the 3D-CAD system. During the design process, the designers cannot fully appreciate the size and operability. All they can do is to imagine the size and the operation scene in their mind. By using our latest prototype system, the designer starts to draw the control room roughly (Fig. 16 (a)). Then the designer teaches the system the operation of levers, buttons, and warning lights (Fig. 16 (b)). The designer finds several problems (Fig. 16 (c)) and fixes them by redrawing the sketch (Fig. 16 (d)).

Note that all this is done by hand-drawn sketches. The scenario can be done in less than one hour.

Special User Interaction for the New Design Concept

The new design concept "life-size and operability" requires new interaction methods.

Interactions for "life-size"

Since it is difficult to draw a life-size image, our system has several unique interactions. Here three interactions are shown.

The color of the drawing line changes at the fixed length (50cm) as shown Fig. 17. The designer can recognize the length of the line while drawing the lines. Fig. 17. Line length notification. Fig. 18 shows the lead line. It is a kind of auxiliary line. The designer is drawing a refrigerator (red box) between two real drawers. The lead line-A connects the designer's body (left hand) and the virtual image (refrigerator: red box). If the designer moves his/her left hand, the lead line-A moves too. The lead line-B connects two real objects. It is literally a static auxiliary line drawn in the real world. The lead line-C connects the designer's body (waist) and the real object (right drawer).

These lead lines help the designer grasp the 3D location of real and virtual objects. Since the drawings are life-sized, they tend to be big. Therefore, the selection of the object is difficult. Our system has a few selection methods. Fig. 19 shows the projection based selection. The designer draw a closed line in front of him/her, the closed line is projected conically from the center of the designer's eye. The drawings included in the projected volume are selected. The closed line can be drawn in the different space. Then the merged volume is the selected zone as shown Fig. 19. Interactions for "operability"

The designer teaches the part of sketch how to respond to the users' operation (behavior) in three steps. An example (Fig. 20) shows how to teach the operability of the control board, which consists of two color lights and one lever. The operability of the control board as follows; -Lever moves vertically -Light changes color in accordance with the lever's position In the first step, the designer draws the overview of the control panel with two color lights and one lever (Fig. 20 (a)). In the second step, the designer teaches the operation of single component, i.e., the state transition (ex. On/OFF switch, color light) and the trajectory movement (ex. lever (vertical move), dial (cursive move)). For example, in Fig. 20 (b), the designer teaches the trajectory movement of the lever by selecting the sketch of lever and moving it vertically. In the last step, the designer teaches the cooperation of multiple components. In Fig. 20 (c), the designer teaches the cooperation of the lever and the light by moving the lever at the terminal point and then switching the light to the preferred color.

Current prototype system

The current prototype system consists of a see-through HMD, head-tracker, 3D-pen, and palette (command board) as shown in Fig. 21. The 3D position sense is implemented by combining the ultrasonic and magnetic sensor to handle a large 3D sketch, such as a control room. To promote the cooperative design, three or more HMDs (maximum 6) are connected.

Preliminary Evaluation

We conducted a preliminary evaluation with the help of professional designers. The subjects were 5 students and 1 professional designer. All of the subjects took a training course that covered all interaction methods in 17 scenarios. The preliminary evaluation took place after they completed all the scenarios.

In the preliminary evaluation, all subject were given the design theme concerning to the new copy machine, then they began to design freely.

CONCLUSION

This research began from the serious realization that 3D sketch systems were not used by professional designer in real design fields. They are treated as if they were just mere attractions in an amusement park.

In this paper, we proposed a new design concept, "life-size and operability", which should make the 3D sketch system truly valuable for the designer.

According to the preliminary evaluation, the design concept seems promising. However, its validity has not yet been completely proven. We are now obtaining the data by applying it to real world design.

Systems 3 and 4 Systems 1 and 2 2DFig. 2 .

 422 Fig. 2. Typical design flow.

Fig. 3 .

 3 Fig. 3. Image of design flow and environment.

Fig. 4 .Fig. 5 .

 45 Fig. 4. Prototype system "Godzilla".

Fig. 6 .

 6 Fig. 6. Design flow in "Extended Godzilla" system.

Fig. 7 .

 7 Fig. 7. "Extended Godzilla" System.

Fig. 8 .

 8 Fig. 8. "Pull and Push". Fig. 9. Example.

Fig. 10 .

 10 Fig. 10. Use of "Shadow" and "Hand Mirror".

Fig. 11 .

 11 Fig. 11. Categories of four force fields.

Fig. 12 .Fig. 13 .

 1213 Fig. 12. Photo of prototype system.Fig. 13. User interface.

Fig. 15 .

 15 Fig. 15. Copy machine design example.

Fig. 16 .

 16 Fig. 16. Control room design example.

  Modification of SketchOh, my hand cannot reach this lever when seated! Oh, when this button, I cannot look at the red warning light! 6.3.1

Fig. 18 .

 18 Fig. 18. Three types of lead line.

Fig. 19 .

 19 Fig. 19. Selection by projection.

Fig. 20 .

 20 Fig. 20. New interactions for "operability".

Fig. 21 .

 21 Fig. 21. Current prototype.See-through HMD

Fig. 22 . 8 )

 228 Fig. 22. System overview.

Fig. 23 .

 23 Fig. 23. User's view through HMD.

  Fig. 24 and Fig. 25 are the photos of the experiment.

Fig. 24 .

 24 Fig.24. Behavior of subject-A.

Fig. 25 .

 25 Fig.25. Behavior of professional designer.

Fig. 27 .

 27 Fig. 27. Design result-B.

Fig. 28

 28 Fig.28is the analysis of the professional designer's behavior while operating the 3D sketch. Fig.28implies that the designer willingly drew the life-seized sketch and frequently operated the 3D sketch to check the usability of the copy machine.

Fig. 28 .

 28 Fig. 28. Analysis of professional designer's behavior.

We hope our research is helpful to design the multimedia-based support system for professional use.

We videotaped the design process of 6 subjects and analyzed the specific behaviors.

Table 1 shows the frequency of the new interactions for "life-size", proposed in the section 6.3.1. All subjects have used all interactions and frequently used the selection by projection. The prototype system had several methods for the selection since it was difficult to select the part of the sketch that floated in the midair. For example, the prototype system had the direct selection method in which the user touched one line by one line and the touched lines were selected, the volumetric selection method in which the user defined the rectangular solid by drawing the diagonal line, and the lines in the volume were selected, and so on. Because of the "life size" nature, the selection by projection seemed to be preferred.

Table. 1. Behavior of "life-size" interaction.

Table 2 shows the behavior of the "operable" interaction. "# of operable sketch" does not mean the number of the operable sketches which remained in the final design but the number of the operable sketches which were drawn in all the design process (i.e., includes the try and error sketches). All subjects drew many operable sketches. Since one co-operable sketch consists of at least two single component, so the average number 5.5 means that at least 11 components are used in the co-operation. Surprisingly, almost all single components worked with other components. Also the number of operations 16.0 was so high that they seemed to focus on the usability evaluation. Table 3 lists several statistics on the final design. They tend to use many colors that were used to show the different parts. The final design contained 6.8 operable components and 2.5 co-operable rules in average. They drew more operable sketch than we expected. Only half of the sketch components remained in the final design. It might be explained by the trial and error approach in designing of the interaction.

Table. 3. Statistics of final design.

Fig. 26 and Fig. 27 are the results of the design. Note that the designs are real-sized and operable. Fig. 27 is the design result when the designer was asked to design a novel copy machine such as "never before seen copy machine". They successfully designed a "novel operable" copy machine, which was a round copy machine usable from any direction. Note that the round tray is also operable.


Christophe Ponsard
email: christophe.ponsard@cetic.bepascal.beaujeant

Pascal Beaujeant

Jean Vanderdonckt
email: jean.vanderdonckt@uclouvain.be

Augmenting Accessibility Guidelines with User Ability Rationales

Keywords: Accessibility, Assessment, Web, User-Model, Task Model, Ontology, Guidelines, WCAG

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Keeping the web accessible to all and especially to people with disabilities has become fundamental given the importance the web as gained in many aspects of life such as education, employment, commerce, health care, government, leisure, and more. Considering sight and hearing impairments which are among the most problematic when considering web usage, about 6.4 percent of the population age 15 years and older and more than 20% of the population over 65 is concerned in the US, according to a 2010 report [START_REF]Americans With Disabilities[END_REF]. Those figures can be transposed to other developed countries and are far higher in developing countries.

Applying accessibility principles is also widely recognised as enhancing the overall usability experience for everyone whether or not suffering impairment. Accessibility standards such as the WCAG [START_REF]Web Content Accessibility Guidelines[END_REF] or section 508 [11] are widely recognised and formulated as practical guidelines to ease adoption.

Despite those facts, recent reports keep showing that the level of accessibility remains very low. For example, a 2008 European Commission study highlighted that only 2.6% of key public and commercial websites in Member States were accessible, while only 5.3% of government websites were accessible [START_REF]Web-accessibility in European countries: level of compliance with latest international accessibility specifications, notably WCAG 2.0, and approaches or plans to implement those specifications[END_REF]. Explaining the gap between the need and the current lack of accessible websites is not easy and multiple factors are involved. The fast pace of technical evolution does not help but beyond that, one of the key reasons frequently mentioned is the lack of information and training of web designers.

Accessibility guidelines have quite matured and now clearly separate the accessibility principles and guidelines from specific techniques to enforce them in specific technologies [START_REF]Web Content Accessibility Guidelines[END_REF]. However, while web designers are well armed to face "how" to apply the principles, the support to help them understand "why" they need to apply specific guidelines is still largely missing; e.g. the WCAG2, focussed upon in this paper, does not explicitly relate the need of captions in video content with deafness.

In order to provide better support for the web designer, this paper proposes to enhance the existing guidelines with such rationales. We show how to systematically produce them based on the existing guidelines combined with user impairment ontologies and user interface modelling techniques abstracting from the pure implementation level (such as abstract user interfaces and tasks models). In order to represent and reason about the accessibility related knowledge, we rely on semantic web techniques like RDF/OWL representations, queries and ontology interconnections [START_REF]OWL Web Ontology Language Reference[END_REF]. Those techniques also enable an access as open linked data.

The structure of this paper follows our research approach. First, in Section 2, we survey the available models and related ontologies which can be exploited and connected to better support the design process. Section 3 then details how additional links can be inferred to bridge important gaps such as the rationales between guidelines and user impairments. Section 4 then illustrates a number of scenarios on how the enriched guidelines bring added value. Section 5 reviews some related works; and finally section 6 concludes by highlighting how this work can be further developed.

Survey of accessibility related ontologies and models

This section presents the characteristics (strength/limitations) of existing accessibility and impairment ontologies as well as relevant User and UI modelling techniques.

Accessibility and Impairement Ontologies

Web Content Accessibility Guidelines. WCAG guidelines are expressed as principles in four major categories: perception, operability, understandability and robustness. Those are refined into 12 major guidelines which are then supported by specific techniques, either generic or specific to a technology. Related checks are also defined to keep the traceability between these guidelines. Its structure can be represented as a goal refinement tree depicted in Figure 1 and explained in more details in section 2.2. The guidelines are mostly available as well-organised structured hypertext on the W3C website. The AEGIS project has also made them available as ontology under the OWL format which can be used for semantic processing [START_REF] Vanderdonckt | Open Accessibility Everywhere[END_REF]. Figure 2 illustrates this ontology in the Open Source Protégé tool.

Models

User Interface Models provide representations of the user interaction with a computer program or another reactive device with the purpose of supporting the UI design and analysis process. Different aspects of human-machine interaction can be captured by a set of the following complementary models and are supported by specification languages like UsiXML [START_REF] Vanderdonckt | USIXML: a User Interface Description Language for Specifying Multimodal User Interfaces[END_REF].

 Task model enables the description of high-level user requirements in terms of activities to be performed by the user and/or by the system in order to reach some goal [START_REF]W3C, MBUI -Task Models[END_REF]. They have a hierarchical graphical syntax with a well-defined semantics.  Abstract UI model defines interaction spaces grouping subtasks according to various criteria and independently of any context/modality of use.  Concrete UI model define widgets layout and navigation. While making the Look & Feel explicit, it is still a mock-up rendered in a non-operational environment.

Goal models are used in the larger context of requirements engineering of system [START_REF] Van Lamsweerde | Requirements Engineering: From System Goals to UML Models to Software Specifications[END_REF] while task models are more specifically targeting UI design. Goals capture properties to be achieved by users together with the systems. Goals can be refined hierarchically and can be seen to some point as a generalisation of tasks. Goals support reasoning about obstacles and conflict by taking into account known domain properties (in our context: UI characteristics and user impairments).

Producing Guidelines Rationales

In this section, we present the process to generate accessibility guideline rationales, based on existing techniques used among other in requirements engineering such as obstacle analysis and abduction techniques based on domain knowledge [START_REF] Van Lamsweerde | Requirements Engineering: From System Goals to UML Models to Software Specifications[END_REF]. This rationale generation process is depicted in Figure 4 and relies on the following steps:

1. Content types are extracted from the models, possibly at different level of abstraction (e.g. task model, abstract UI model if available or concrete UI) 2. Obstacle analysis is performed based on the user capability ontology (e.g. ICF). 3. Matching is made with existing guidelines provided by the guideline library (e.g.

WCAG2)

The process can be complemented by a bottom-up phase, starting from the existing guidelines and attaching them to obstacle or completing existing obstacle trees. The systematic application of the above process revealed two interesting points. First, it acts as a completeness check to detect partly addressed impairments in some usage context. Second, some models seem to relate more specifically to certain functional impairment categories (see Table 1). This can help having a special focus when building those models or even support the decision to build such models.

Usage Scenarios

The availability of the guideline rationales enables new usage scenarios for different target groups (web designers, developers, assessors,...). The scenarios reported here were identified together with Anysurfer (http://www.anysurfer.be), a major association active in accessibility assessment and training. Some subjective validation elements are also reported.

Providing user-related explanations for web designers

Currently, the application of guidelines produces a global ranking such as A, AA, AAA with limited explanations in terms of passed/failed checks. Problems can be traced to guidelines and corrective actions. The rational information enables to:

 state which kind of user is impacted by a failed check. The feedback is this helps web designers to better identify the type of impaired users and to better understand and to apply the relevant parts of guidelines.  provide finer grained assessment going by functional impairment going beyond "black box" A/AA/AAA labels. Some development can for example target a specific user group for which extra requirements have to be implemented.

This support to web designers can be part of an accessibility assessment report but larger gain is expected when it is applied at design stage.

Aligning guidelines for web designers

This paper is focusing on the WCAG2 which are the major reference guidelines. There are however other guidelines such as section 508 in the US and BS 8878:2010 Web accessibility in UK. For global websites or websites in countries transitioning to WCAG, it is more effective to be able to compare between guidelines rather than performing multiple independent assessments. The proposed process can be applied to multiple guidelines with the same structure, resulting in a natural alignment of guidelines as illustrated in Table 2.

4.3

Checking gaps in the guidelines for accessibility working groups

As mentioned in Section 3, the completeness check can point out some obstacles not addressed by the considered guidelines. The validation with accessibility assessors revealed some possible reasons for this: the topic might be related to usability rather than accessibility, or corrective measures might have been considered too advanced/costly to implement. In all cases, it was found interesting to report this information for helping in the future evolution of the guidelines. Some issues can also be reported to web developers as recommendations going beyond the current guidelines.

Related work

Applying ontologies to accessibility has already been proposed. For instance, [START_REF] Xiong | Towards an Ontology-based Approach for Dealing with Web Guidelines[END_REF] shows how they help in addressing limitations of natural language but without referring to specific guidelines. This is now a recognised approach as shown in Section 2.

The idea to connect ontologies has been investigated in [START_REF] Karim | Providing universal accessibility using connecting ontologies: a holistic approach[END_REF]. A generic accessibility pattern connecting user, capability, interface element and information has been proposed and instantiated to various examples (memory/recall, perception). The work however does not explore the use of renown and standard ontologies like the ICF and WCAG as proposed in our work.

An alternative approach proposed in [START_REF] Oikonomou | An Accessibility Assessment Framework for Improving Designers Experience in Web Applications[END_REF] is to build a specific ontology formally describing the whole information about user's impairments, and the available interface characteristics. This allows a personalised accessibility assessment but the presented scenario does not seem to support the detection of partly covered impairments. We also believe it is better to avoid mixing ontologies addressing different domains to ease future evolution, for example considering different sets of guidelines.

The project ACCESSIBLE developed a harmonised methodology for measuring accessibility, including guideline alignment [START_REF] Mourouzis | A Harmonised Methodology towards Measuring Accessibility[END_REF]. Though quite similar, that work looks ICF-driven (top-down) while our approach can also be guidelines driven (bottom-up). The work also covers the alignment of guidelines such as WCAG1/2 and section 508.

AEGIS project developed an Open Accessibility Framework relying on ontologies [START_REF] Vanderdonckt | Open Accessibility Everywhere[END_REF]. It supports the mapping from requirements/constraints of users to characteristics not only of web applications but also desktop and mobile applications. The AEGIS generic accessible user interaction model shares similarities with our work although it is more directed towards personal customization scenarios.

Conclusion and perspectives

The paper shows how accessibility guidelines can usefully be extended to better support accessibility rationales providing better explanation why specific guidelines are required by linking them to impairments. A number of interesting scenarios exploiting these rationales have been identified and investigated. At this point, the resulting combined ontology is still partial but available from http://www.accessible-it.org/ontologies. On-going work is to enrich them and achieve integration with existing frameworks in order to conduct validation experiment inside a local cluster of web SMEs. We also plan to investigate more specific user capability models such as the DSM-5 [START_REF]DSM-5 Development[END_REF] dealing with cognitive disorders.

Fig. 1 .

 1 Fig. 1. Partial goal model for WCAG2 guidelines.

Fig. 2 .

 2 Fig. 2. WCAG2 Ontology.

Fig. 3 .

 3 Fig. 3. ICF Concepts and Relationships.

Fig. 5 .Fig. 6 .

 56 Fig. 5. Rationale Generation Approach.

Table 1 .

 1 Impacted functions in relation with UI models.

	UI model	UI concepts (added from previous level)	Impacted functions
	Task	Information flow, navigation flow	Cognitive
	Abstract UI	Controls, content types	Motor, Vision, Hearing
	Concrete UI	Look and Feel (styles, colors)	Vision

Table 2 .

 2 Guideline Alignment example.

	ICF	Obstacle to address	WCAG2 Section 508
	b.21021 Seing fion: colour vision	Colour only information	G1.4.1	1194.21i
	b.21022 Seing fion: contrast sensi-	Contrast enhancement	G1.4.3	1194.21g
	tivity		G1.4.6

Acknowledgement

This work was funded by the QualIHM project (grant nr 1217570) as part of the collective research programme of the Walloon region. We warmly thank the Belgian AnySurfer association and the reviewers for their insightful feedback.