Boriana Koleva, Ian Taylor, Steve Benford, Mike Fraser, Chris Greenhalgh, Holger Schnädelbach
School of Computer Science, The University of Nottingham, UK

Dirk vom Lehn, Christian Heath
The Management Centre, Kings College London, UK

Ju Row Farr, Matt Adams
Blast Theory

A Description Of Desert Rain

Desert Rain is a game, a performance and an installation created by Blast Theory in collaboration with the Mixed Reality Lab at the University of Nottingham. Commissioned by Contemporary Archives in Nottingham, the ZKM (Centre for Art and Media) in Karlsruhe in association with DA2 in Bristol and the KTH (Royal Technical Institute) in Stockholm, the piece was premiered in 1999. To date it has been presented in Nottingham, Karlsruhe, London, Manchester, Stockholm, Rotterdam, Glasgow, Bristol, Prague and Middlesborough. Desert Rain was shortlisted for an Interactive Arts BAFTA in 2000.

This essay draws on ethnographic surveys using interviews, video recordings and direct observation to explore what techniques are used for orchestrating the participant's experience in Desert Rain.

The Artistic Foundation Of Desert Rain

The central artistic concern of Desert Rain is virtual warfare, the blurring of the boundaries between real and virtual events, especially with regard to the portrayal of warfare on television news, in Hollywood's films and in computer games. Informed by Jean Baudrillard's assertion that the Gulf War did not actually take place because it was in fact a virtual event, both the content and the form of Desert Rain are designed to provoke participants to re-evaluate the boundaries between reality and fiction, and between the real and the virtual. As the players eventually discover, the targets they must find in the virtual world are six people who have quite different perspectives on the Gulf war:

- Glen, a soldier who served in the Gulf War, driving a personnel carrier that collected Iraqi casualties;

- Shona, a soldier who was bedridden at the time of the war and watched it on TV;

- Richard, a peace worker who helped establish a peace camp on the Iraqi-Saudi border in December 1990;

- Eamonn, a BBC journalist who was in Baghdad on the night the air war started;

- Sam, an actor who played a soldier in a TV drama about the Gulf War; and

- Tony, an actor who was on holiday in Egypt at the time.

The set for Desert Rain is a combination of the real and the virtual, each mirroring the design of the other, and connected through the permeable and physically traversable rain-curtain. Finally, the nature of their mission remains a puzzle for the participants: is this a game, a drama or an interactive installation?

Desert Rain From A Player's Perspective

Desert Rain lasts for approximately 30 minutes. The experience begins in the physical world. A performer leads the six visitors into a bare physical antechamber where they are asked to remove their outer clothing and deposit their possessions in a box under their chair. They don an anorak, and are briefed as to their mission. The briefing introduces the six targets, explains how to use the footpads, and stresses the time critical and cooperative nature of the mission. Next, each player is led in turn by a performer to a fabric cubicle and is zipped inside. There they each stand on a personal footpad and put on a headphone/microphone headset.

Each player faces his/her own personal rain-curtain - a large screen, roughly two metres tall by two and a half wide, composed of falling water, onto which is projected an image of a virtual motel room. The image in the curtain has some striking aesthetic qualities: one's attention tends to switch between the image that appears to hang in the water, the water itself and the bright projection lamp that can be seen through the curtain (appearing like a hot sun in the desert sky). The sound of the water is insistent even when wearing headphones. Behind the six curtains, unseen by the players, lurk two performers. The asymmetric nature of visibility through the rain curtain means that these performers can observe the players, without being observed in return. A third performer monitors all six players from the control position and is able to support, encourage and exhort the players via an audio link. Each footpad acts as a large joystick: by shifting their weight on its surface, players can move forwards and backwards or can rotate clockwise and anti-clockwise, navigating around the virtual world that is projected onto their rain curtains.

The action now switches to the virtual world. The six players begin their journey through this world isolated from one another, each in a separate virtual motel room. Each motel room contains a virtual TV set that plays back a short video recording of the Gulf War coverage from CNN news. The player leaves the motel room through a door, passes into an open desert landscape beyond, and heads towards the centre of the world. As the six players draw closer, they find that they can hear one another through the live audio link, mixed in with an ambient soundtrack. They may also hear a performer's voice advising them if they are experiencing difficulties. When they meet, the players see one another represented as orange and grey avatars. Each player must locate their target and move inside it. They find that they are standing inside a rotating white virtual cylinder, facing a sign that says, "Wait here".

The action now swaps back to the physical world. One of the performers who has been observing from behind the rain curtain steps through the curtain, slowly approaches each player, gives them a plastic swipe-card and without speaking turns away and walks back through the curtain. Given that the players have been concentrating hard on the virtual world and that they are likely to be feeling somewhat disorientated, this is usually experienced as a highly dramatic, even shocking, event by the players. As a critic writing in the Sunday Times notes: "This change from virtual to real is remarkably sudden and strangely disconcerting." [Sunday Times, 31 October 1999] Some players cry out aloud or cover their faces.

The action now swaps back to the virtual world. The players are encouraged to find the entrance to an underground bunker. Inside they find a maze of narrow corridors. Together they have to find the exit before their twenty minutes are up. Once found, the exit will only open if all of the players have found their targets (the players are encouraged to help one another to find the remaining targets). If the team passes through the open exit within the allowed twenty minutes, the performers appear again and lead each player forward, passing through the rain curtain - the reward for success. If they fail, the water is switched off before they are led forward to the next stage.

For the final stage, the action swaps back to the physical world. The six players pass into a narrow corridor and climb over a steep mound of sand into a hotel room - but one created by pasting wallpaper-sized photographs onto the walls. A real television set has been inserted into the photographic wall. Using their swipe card, each player accesses a video interview with his/her target. The six clips show quite different perceptions of the Gulf War, revealed through interviews with the six targets. Any player who did not find their target is unable to access the interview.

As the players leave this final room, they are confronted by a text mounted on the wall:

'In 1988 the USS Vincennes was dispatched to the Persian Gulf to help Iraq, under Saddam Hussein, in its war against Iran.
'The warship was equipped with AEGIS, the most sophisticated weapon control system yet developed. It uses 16 mainframe computers and 12 minicomputers to control up to 122 ship-to-air missiles and two six-ton, six-barrelled automatic machine guns capable of firing 3,000 rounds per minute.
'On July 3rd the Vincennes shot down Iranian Airbus Flight 655, killing all 290 on board (more than died in the Lockerbie bombing). While widely reported in the Third World, the incident received little coverage in the Western media.
'The crew of the Vincennes had undergone nine months of simulated scenarios prior to leaving for the Gulf, all of which were predicated on hostile encounters.
'During the crucial minutes in which the airbus was flagged as a hostile F14, the crew ignored indicators that cast doubt onto the AEGIS interpretation of events. Because the AEGIS automatically analyses incoming data, there was no way to directly evaluate the radar blips.
'The commander of the nearby USS Sides "wondered aloud in disbelief" as the Vincennes prepared to fire but did not intervene with the vessel equipped with AEGIS.
'On return to the US, Captain. William Rogers - commander of the Vincennes - received the Legion of Merit award for "exceptionally meritorious conduct in the performance of outstanding service" in the Gulf.'

Finally, the participants change back into their original clothing and emerge from the experience. Sometime later they find that a small box containing an estimated 100,000 grains of sand - a speculation on the number of casualties in the Gulf War - has been left in their pocket.

Orchestration Techniques

The technical foundation of Desert Rain

Technically, Desert Rain is a practical exploration of using mixed reality technology to create a coherent and engaging public experience. The specific mixed reality technology in question is that of traversable interfaces. These establish the illusion that a physical space is joined to an adjacent virtual space and that participants physically pass from one to the other (appearing to dematerialise from physical space and rematerialise in virtual space or vice versa). Early laboratory prototypes of traversable interfaces employed walk-through projection surfaces to create the illusion of physically stepping into or out of the image of a virtual world.

Desert Rain has taken the rain-curtain technology and used it to create a full-scale public performance. The rain curtain was chosen for its aesthetic qualities, both in terms of its striking visual image and sound, its asymmetric transparency (see below), and not least, due to the artistic association of projecting a virtual desert into a curtain of water. In fact, Desert Rain employs six rain curtains to create a shared mixed reality experience for six players that involves a journey through a combination of physical and virtual spaces and interactions with performers who appear to cross from one to the other.

The roles of the performers

The following table summarises the typical division of responsibility between the performers.

Performer 1, antechamber:
Meet and brief the players in the antechamber.

Performers 2 and 3, behind the rain curtains:
Lead players to cubicles and zip them in. Observe players from behind the rain curtains, cross curtains at the correct moment and hand over swipe card. Lead players to the corridor of sand.

Performer 4, control centre:
Monitor players' progress through the virtual world and their conversations. Talk to players over audio.

Performer 5, control centre:
Run, control and monitor software. Help steer players' avatars using the keyboards.

These individuals communicate with one another by whispering when co-located in the control centre or in the area behind the six projectors. They also employ a simple signalling system using flashlights for communication between these two spaces - for example indicating how many players are present in this performance (not always the maximum possible six).

Issues Raised by Desert Rain

Desert Rain has provided us with a valuable opportunity to study the use of computer technology to create an interactive public experience. The aim of our study has been to identify HCI issues and techniques that are relevant to the design of interactive public experiences and that may not be so familiar from the design of more traditional workplace technologies. Our study of Desert Rain forms part of a larger project concerned with conduct and interaction in museums and galleries. We have undertaken extensive studies in various museums in the UK, such as the Science Museum, the Victoria and Albert Museum, and the Courtauld Institute of Art in London. The study of visitors' actions and interactions at, and around, more traditional exhibits presents a useful vehicle for investigations into visitors' experiences of innovative new media exhibits.

Orchestration - Managing The Players' Experience

Computers have traditionally been designed as tools to be applied autonomously by users. Embedded help and tutorial facilities provide users with a means to learn how to tackle problems by themselves. Laurel has offered an alternative view: that designers should consider computers as a form of theatre rather than as tools. The key issue now becomes designing the user's experience so that they become engaged with the content rather than with the technology. "Behind the scenes" activities are required to successfully engage the user and to orchestrate their experience. These have to be hidden from the user's view, so that their engagement with the content is not disrupted. As an example of an actual performance involving computers, Desert Rain offers insights into these issues of orchestration and engagement, especially how they can be achieved by human performers in real-time. In the following, we will see how Blast Theory have developed a range of tacit working practices and procedures for engaging players with the content - setting their expectations and enabling the illusion of traversal - and for monitoring ongoing events and intervening if necessary, with minimal disruption to their engagement.

Setting Expectations And Enabling Illusion

Our observations suggest that, to a large extent, participants believe (or rather willingly suspend disbelief) in Desert Rain. The crossing of the rain-curtain by the performer creates surprise and excitement and helps to enhance the participants' engagement. In order to establish this illusion of traversal, Blast Theory conduct carefully designed actions that lead participants into and out of the different phases of the performance. At several points in the performance Blast Theory deliberately attempt to set the players' expectations, encouraging them willingly to suspend disbelief.

In the antechamber participants are introduced to Desert Rain. As they enter the installation guided by a performer, participants are briefed about their mission in the virtual world and engaged with the game. Before they are isolated from the rest of the group and guided one-by-one to their cubicles and zipped inside, they are advised to make use of the communication facilities in the virtual world. The importance of presenting a back-story prior to an interactive experience is well understood by the imagineers who design theme-park rides.

However, Blast Theory take this a step further. It can be argued that through a range of well-prepared stages, participants are gradually desocialised, like an inpatient in an asylum who "finds himself cleanly stripped of his many of his accustomed affirmations, satisfactions and defences", and are subjected to a set of discomforting experiences. As the participants normally follow the performers' instructions quietly without showing any sign of resistance towards this desocialisation procedure, it seems that the performers' carefully conducted actions do indeed set the players' expectations and enable the illusion of the game. Crossing the curtain - the moment when a player finds his/her target and a performer crosses the rain-curtain - is the climax of the dramatic performance.

After the players have navigated the virtual world for some time, they have become familiar with the game and are ready for new experiences that help to maintain their engagement in the game. Blast Theory have designed the players' discoveries of their targets in a particular way that creates surprise and excitement and makes possible that their engagement with the game is strengthened by the crossing of the curtain. However, the crossing is a moment that is fraught with danger for the performers. The timing of their movement with the players' actions in the virtual world is of crucial importance. When players see the rotating drum for a long time they become disoriented and question its part in the performance. They sometimes assume that the system has crashed and wait for a continuance of the program. If the performer walks too quickly through the rain-curtain, the illusion of his/her emergence from the virtual world does not work. If the timing of the crossing is not right, it disengages the players from the game, and they attempt to involve the performer in conversation.

Leaving the cubicles - the virtual game ends when the players have found the exit to the virtual world and leave the cubicles. The performance, however, continues as the players are led to the motel room. This is perhaps the point in Desert Rain when it is most difficult to sustain engagement. It seems that players often assume that with the end of the virtual game the performance comes to an end as well. In early performances, they would meet their co-players in front of the cubicles where all of them would take off their anoraks, and then discuss with each other their experiences in the virtual world. Sometimes they would attempt to return the swipe cards to the performers. Only when they were asked to climb the sand hill did the tension build up again. However, it then collapsed again only a few seconds later after they had gathered in the motel room. Their excitement about the experiences in the virtual world appeared to take over and they began discussions with each other. They disengaged from Desert Rain prematurely.

In response to these observations, Blast Theory altered their orchestration of this part of the performance. The players no longer removed their anoraks until after the final motel room. Furthermore, the performers carefully planned the order in which to take the players from their cubicles, so that the players spent the minimum possible time together before moving on up the sand hill, and also so that the performers were best positioned to shepherd them on.

This last observation shows the level of detail that has to be considered when planning and executing a performance. This is a key point. The interactions with the players are meticulously planned and repeatedly rehearsed, including dialogue, inflections, gestures and speed of movement. Potential problems are identified in advance and responses are rehearsed, with a particular focus on how they can be woven into the experience.

Monitoring and Intervening

Our observations indicate that the performers largely manage to lead the participants into the installation and engage them with the game. However, to ensure that the players' engagement with Desert Rain is maintained throughout their journey, performers continually monitor events in the virtual as well as in the real world. If the players' engagement with the game seems to be endangered at any point, performers have to hand a range of prepared actions through which they can intervene in events. The players are never really isolated in their cubicle as the design of the installation allows the performers asymmetric access to the players, both in the virtual and physical worlds (through the computer monitors in the control area and the asymmetric nature of the rain curtain respectively). Monitoring and intervening can therefore largely be accomplished without the players noticing it.

We have identified three styles of intervention. Off-face interventions are conducted by the performer at the control centre to advise players about actions in the virtual world. Occasionally, the performer also attempts to influence the player's movement on the footpad. Off-face interventions are produced by means of the audio link to talk to a player and to advise her on which directions to take in the virtual world or on the use of the footpad. They cannot be conducted without the players noticing them. But performers use a specially designed, dramatic voice and almost always manage to embed the intervention within the game, thus preventing the players from becoming distracted from their actions within the virtual world.

As with other recent digital media artworks, Desert Rain is designed to promote collaboration among participants. Another opportunity for off-face intervention is therefore encouraging the players to help each other, for example, suggesting that players who have already found their targets go back and help their team members who have not. Given that we found communication between the players to be an especially enjoyable and engaging aspect of Desert Rain, this provides an ideal way of intervening without breaking engagement.

Virtual interventions are carried out from the control centre by virtue of the arrow keys on the computers. They are very carefully conducted so that the players do not notice them. For example, when a performer observes that a player has been circling her target for some time without crossing it, s/he focuses his/her observation on this player's movement in relation to the target. As the player comes very close to his/her target the performer presses an arrow key to push the player's avatar through the target, and thus triggers the rotating drum. The performer makes her decision about the exact moment to push the arrow key with great care so that it is neatly timed with the player's movement in the virtual world. S/he moves the avatar only a tiny bit, thus making sure the push remains unnoticed by the player. Indeed, it ensures that players do not get frustrated as they circle their target.

Face-to-Face interventions are carried out by a performer who directly approaches the player's cubicle to give practical advice on using the footpad. This form of intervention is very intrusive and always results in an interruption of the player's engagement in the game. Therefore, it is only employed on very rare occasions. A few players have been observed who despite having received advice through the audio-link, could still not use the footpad; in order to enable them to engage in the game a performer accessed their cubicle from behind to give them hands-on support. Face-to-face interventions were only employed when off-face interventions did not work and were normally preceded by communication between the control centre and a performer behind the rain-curtain.

Conclusions

Blast Theory's Desert Rain takes Brenda Laurel's concept of "Computers as Theatre" literally. A computer system and its use by members of the public are embedded within a dramatic performance. In order to ensure the success of Desert Rain, the performers carefully set the participants' expectations and produce a range of performances and unobtrusive practices to orchestrate their experiences. Key aspects of this orchestration are:

- Carefully planned and thoroughly rehearsed briefings and interventions at all stages of the performance;

- The use of off-face and virtual interventions so as to sustain engagement;

- Encouraging the players to help one another as a way of intervening and yet increasing engagement;

- The ability to monitor action in both the physical and virtual worlds through asymmetric interfaces.

We think that these observations may have broader implications for HCI.

As the need to monitor an d intervene might be seen as a downfall of the "usability" of Desert Rain's interface, it is worthwhile considering that currently more and more computer systems, such as information kiosks and touch screen devices, are placed within public places. Appropriate user support for such applications is often not available, leaving the user alone and sometimes frustrated or even embarrassed in the public eye.

We suggest that the ability for technical crew to dynamically manage a participant's experience will be increasingly important in a range of applications. Continual and unobtrusive observations of the user's (inter)actions with the system and within the virtual world are necessary so to be able to embed interventions within ongoing actions and experiences. This requires a repertoire of social practices supported by appropriate technical facilities. Of course, this should come as no surprise - traditional theatre already has well-established practices and facilities for managing performances - lighting, sound, curtains, scenery and so forth. Similar facilities are now required for managing computer-based experiences.

Finally, despite the public accessibility of computer systems as they are currently deployed in museums and galleries, they are normally developed for use by individuals, isolating the user from his/her companions and the wider environment. In contrast, Desert Rain indicates that participants may be willing and able to support each other while remaining engaged in an experience. Indeed, the communication involved in mutual support might even strengthen their engagement.

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