Presence is crucial to participants feel sense of being in a virtual environment. Enhancing presence as a psychological phenomenon can offer participants a special subjective experience, rather than the purely observational experience like that of television or film. Presence is composed of three dimensions: (i) social presence relates to a sense of “being there”; (ii) personal presence connects to feeling of “being there with others”; and (iii) environmental presence presents the existence of virtual space. This project will develop ‘presence’ by using multiplayer, avatars and free walking in 3D scanned environment. The components of this project allow participants to exist with others in virtual environments and experience virtual reality with others. This report will argue that multiplayer virtual experience can provide participants with stronger feelings of being present in virtual space than single-player experiences, and that the existence of other players can emphasise ones presence in virtual environment.

1.Introduction

Over the past few decades, Virtual Reality (VR) has developed dramatically and is now being investigated across the world. It is employed wide range of fields, such as education, training, athletics, industrial design, architecture and landscape architecture, urban planning, space exploration, medicine and rehabilitation, entertainment, and model building and research in many fields of science (McLellan, 2001). This novel technology can create a three dimensional first person experience by enveloping them in a virtual space. The space provides users with a different experience from that of other media, such as a film, which is an edited third person experience. With a head mounted display, in VR participants can go into and explore the space from their own point of view. Many recent studies have tried to create highly realistic experience in VR by merging human sensory stimuli, such as touch, hearing and smell. These stimuli invoke a ones pre-existing knowledge of every day experience and enhance user’s sense of presence, which is feeling of “being there”. Many studies try to represent physical reality in virtual environment by using these stimuli (Simeone, Velloso and Gellersen, 2015). However, personal sensation is not only way to replicate the real world, there are many other components that construct our perception of reality. Existence of others is the one of these components, indeed we share everyday life with others. According to Berger and Luckmann (1966), through face-to-face communication and social interaction we share a common sense of everyday life. Reality is constructed together, and therefore we are all the components of real world. Therefore, it is likely that communication and interaction with others in virtual space can enhance our collective sense of reality and ones own feeling of presence.

 

Current VR experiences have some difficulties in enhancing the sense of presence for users because of the fact participants cannot walk freely around virtual environment without an advanced tracking sensor. Even if a participant is allowed to walk around virtual environment, they need to be tracked by a Kinect sensor to detect their motion. Users are only able to look around virtual environment from a fixed camera position with head tracking system. This may give users the same feeling as traditional story-telling media that is edited by a creator. Moreover, a head mounted display must be connected to a computer in order to show virtual environment. Therefore, even if it is possible to walk around virtual space with a Kinect sensor, the user must clear adequate space to physically to avoid bumping into physical objects. Participants must be mindful of their immediate physical environment when they experience VR with head mounted display, thus, it is difficult create immersive VR and enhance the sense of presence for current cabled VR experience.

 

“Palimpsest” is multiplayer virtual experience that I designed with my project team. In this project, we present an interactive social VR experience without any external sensor to enhance user’s sense of presence in the environment. The main questions of this work are threefold: (i) ‘to what extent social virtual reality experience enhances user’s feeling of being present?’; (ii) ‘how can the existence of others enhance the sense of presence of oneself?’; and (iii) ‘how does free walking affects participants each other?’. This project will use Unity Game Engine software and Project Tango hardware. In our system, most of the computational simulation is based on real-time object and participant motion tracking. Participants are followed by Photon network transmission service, and then the users can see each other as an avatar within the virtual environment in real time. We believe that this project will provide locomotive virtual experience and social virtual experience, and these combined experiences can enhance participant’s sense of presence in virtual reality. The following sections explain the theoretical background of this project, and how my project team and I tackled each of the questions throughout this design work. The project analyses the theoretical background and it is designed based on the background to answer the questions.

2.Importance of Presence in Virtual Reality

[Figure 1] The first head mounted display by Professor Ivan Sutherland in 1966 (http://www.hololensdevs.com/wp-content/uploads/2015/04/Ivan_Sutherland.png [Accessed: 11th August 2016])

Virtual reality was initially presented by Ivan Sutherland in 1965 (Mandal, 2013), and can be defined as a class of computer-controlled multisensory communication technologies that enable the user to interact with data and to engage senses in new ways (Mclellen, 2001). It simulates environments electronically to experience through head mounted eye goggles and wired clothing enable interact with data in realistic three-dimensional (3D) situations (Steuer, 1993). It can simulate a real or an imagined environment that users can experience virtually in 3D (Onyesolu and Eze, 2011). VR therefore enables the user to visualise, and feel, 3D space as a first person experience. Onysolu and Eze (2011) also point out that VR provides for the first time participants with a realistic feeling of being in a computer generated virtual environment. In the virtual environment, the user’s locomotion is tracked and their surroundings are rendered in real time (Fox, Arena and Bailenson, 2009). The perspective of the user is always maintained by their physical motion and/or controller inputs. If a user moves his or her character forward in a VR computer game, the view follows the character and new surroundings are rendered. The tracking and rendering system combine to provide much higher level of interactivity then traditional media such as films (Fox, Arena and Bailenson, 2009). The low interactivity of tradiational media mean that it is difficult for other media to provide a plausible first person experience for the user. Newspapers and letters put the reader in a space where the writer is telling a story, television places the watcher in a virtual space where both viewer and on-screen objects are present, video games can create virtual space where the player is an actor (Steuer, 1993). Mostly, however, traditional media provides the user with a third person experience that controlled by a creator. In contrast, creation of the first person experience is arguably the primary purpose of VR. According to Fox, Arena and Bailenson (2009), the ultimate aim of VR is to replace the cues of the real world with digital ones. VR is able to not only show participants some scenes through a head mounted display, but it can transport user to a novel virtual environment and create sense of presence in the novel environment. Witmer and Singer (1998) indicate that the degrees of presence experienced by the user affect perception of virtual space. Many studies have attempted to imcrease the sense of presence; for example, fully immersive VR enhances presence by capturing human motion and closely reproducing this motion in the virtual environment (Patel and Bailenson, 2006).

[Figure 2] The ultimate image of virtual reality from music video by Duke Dumont

The VOID is a fully immersive VR game (Figure 3) that requires participants wear a vest with haptic feedback to simulate sensations like getting shot (Metz, 2015), gloves that enable players to interact with the virtual space, such as press buttons and pick up objects like they do in real world (James, 2015), and head mounted display in order to motion track accurately and precisely. Participants walk around virtual environment at the same time of physical space. Their virtual environment is perfectly combined with physical reality, participants can therefore play the game as-if they are in a physical environment, physical actions directly affect the virtual environment. As a result, the participants report feeling their presence in virtual environment, their body enters the virtual world (Sra and Schmandt, 2015). Presence may be the cue that the virtual environment has replaced the real physical environment. Therefore, by increasing presence, users may experience the virtual reality as they would the real environment.

[Figure 3] Immersive VR experience by THE VOID.

 

3.Presence

A basic definition of presence is the sense of being an environment (Steuer, 1993). A feeling of presence in a virtual space derives from sense that one exists within the environment (Heeter, 1992). This is a common psychological phenomenon due to space perception (Lee, 2004). According to Wilcox. et al., (2006), sense of presence is enhanced when the virtual environment contains virtual body simulating humans and represent other participant’s avatar. It is likely that in the virtual environment, the existence of ones avatar and anothers’ avatar in the environment are crucial components for presence. Heeter (1992) posited that the three components of presence are; personal, social and environmental, such that ones feeling of virtual space may be enhanced if you experience these three dimensions.

3.1.Social Presence

Social perception is defined as the sense of “being together with another” (Heeter, 1992), and “degree of salience of others in a mediated communication” (Short, Williams and Christie, 1976). This is about social connections that a user makes to entities within a virtual space, and the degree of social presence influences on one’s feeling of being in a virtual environment (Hudson and Cairns, 2014). Therefore, social presence is the most crucial perception that occurs in an environment and it is fundamental in person-to-person communication (Short, Williams and Christie, 1976). This means that societies play an important role in human perceive reality (Heeter, 1992). Indeed, there is evidence that even in the real world, if other people ignore you, you may begin to have a question existence of yourself (Heeter, 1992). Heeter proposes that if others recognise you in virtual environment and are able to interact with you, this can offer evidence to you of your existence. In everyday reality, we communicate and interact with others all the time; therefore frequent communication and interaction with other people within VR may enhance sense of ones own and other’s existence in virtual environment.

vTime is a great example of a virtual experience that is both communicative and interactive (Figure 4). vTime is a VR social networking service that allows users to socialise their friends and family in a virtual environment. Each user is represented with an avatar and is able communicate with other avatars within the virtual space. It is likely that a participant can feel they are present within the virtual space, because others who communicate with you also exist in virtual environment as an avatar.

[Figure 4] Social VR experience by vTime.

According to Gunawardena (1995), social presence is enhanced with intimacy and immediacy. Intimacy, defined as a function of eye contact, physical proximity (Tu, 2002). Immediacy is the psychological distance between a sender and a receiver of communication (Tu and McIsaac, 2002). Both intimacy and immediacy are contributed to through verbal communication (Tu, 2002), and nonverbal interaction (Rettie, 2003). Moreover, seeing each other in virtual environment strengthens the social sense of being together (Heeter, 1992).

 

3.2.Personal Presence

Personal presence is subjective feeling of “being there” (Casanueva and Blake, 2001), and of being a part of the environment (Schuemie, 1999). This presence contributes to subjective sense of “being in an environment”, and lead to feeling of visiting, rather than simply seeing images, of places (Slater, Usoh and Chrysanthou, 1995). The degree of personal presence depends on the number, and fidelity, of sensory input and output channels (Zeltzer, 1992). Furthermore, it seems important to represent reality in virtual environment to enhance personal presence. Indeed, according to Held and Durlach (1992), it is important to create similarity of operator’s physical body and virtual body for experience personal presence. For instance, if a virtual hand mimics the movement of a participants’ real hand when moved, this can cause an illusion of ownership (Argelaguet. et al.,2016). This simulation of the real world increases the sense of personal presence; the user perceives that they are in the environment because images in the space move in accordance with their expectations (Heeter, 1992). Through sensory simulation, participants feel the sense of “being there” in virtual space (Zhao, 2003). BeAnotherLab’s Gender Swap (Figure 5) is an experience that male and female participants exchange their view through a head mounted display. Using head mounted displays and cameras, participants effectively exchange their point of view, encouraging them to embody the other participants body as their own. Participants are required to move synchronized with another participant’s movement during this experiment. The avatar is synchronized participant movement near perfectly; close enough that the illusion is plausible. Thus, the participants can feel the virtual body as their own, even the virtual body is different gender (Bertrand. et al., 2014). Synchronized and natural movement are both important components to create an illusion, this illusion may lead to enhancing sense of “being there”, or presence.

[Figure 5] Gender Swap by BeAnotherLab.

In addition, having a virtual body, such as an avatar, is crucial for the feeling of presence (Casanueva and Blake, 2001), because it allows participants to recognise self-location and identity through their virtual body. Heeter (1992) points out that unlike in a third person experience, you can notice yourself in virtual environment by seeing yourself as part of the scene, and thus can also stimulate sense of personal presence. The existence of participant’s virtual body in virtual environment is a critical factor for feeling personal presence in virtual space.

 

3.3. Environmental Presence

Environmental presence is perception that a virtual environment exists and that the user is present within it (Carassa, Morganti and Tirassa, 2005). This is considered as psychological state that participants can feel they are located in a virtual environment physically and interact with virtual objects (Wirth. et al., 2007). Therefore, environmental presence depends upon the effectiveness of the interactions between the participant and the virtual space (Zimmerli and Verschure, 2007), for example, when virtual objects and the surrounding environment respond to the actions of the user (Heeter and Allbritton, 2015). even simply moving around and past objects in virtual space (Bennett, 2008). Sherdan (1992) points out that the modification of a virtual environment may be an important factor for environmental presence, especially when there is are natural interactions between the user and their surroundings. Conversely, if participants are devoid of environmental presence, they may not immerse at all within the virtual space (Fox, Christy and Vang, 2014).

A high degree of environmental presence will increase immersion of virtual experience. For example, Job Simulator is interactive virtual experience run by Owlchemy Labs (Figure 6) in which the user interacts with virtual objects and a virtual environment. For instance, one may grab a paper airplane using the virtual hand and toss the plane into the air, or even turn on or off a table lamp. As Sherdan (1992) indicated, where interaction with virtual objects influences the virtual environment, interaction may increase participant’s sense of presence. Moreover, personal and social presence are both closely linked with environmental presence because they share similar awareness in the environment (Moskaliuk and Kimmerle, 2011).

[Figure 6] Job Simulator by Owlchemy Labs

 

4.Project Design

4.1 Multiplayer

4.1.1 Photon Network Service for Unity Game Engine

[Figure 7] Network system in this project.

This project is built on Unity 3D and implemented multi-play by using Photon Network Service. Unity is a C# and Java based multi-platform game engine to create interactive 3D program. Photon Network Service is a cloud service that is downloaded from Unity Assets Store. By using this service, real-time multiplayer games are created easily. This service provides pre-programmed features that are ready to use, such as lobbies, matchmaking, buddy lists, leaderboards, and more (Chithra, 2015). In this project, we use Wi-Fi to connect each head mounted display.

When the first participant starts a program, a virtual room is created and they become a host of the program. Other participants must start the program after the first participant, the host, has created a room for other participants to join. If all participants were to start at the same time, each would create their own room and therefore be unable to occupy the same virtual environment. Each participant has different spawn points that they begin in different locations in the virtual space. When joining the room, participants face towards each other. Each participants’ movement data is continuously updated between participants in real time. Participants can recognize what others do in virtual space through Photon Networking. As Heeter (1992) pointed out before, even simply seeing each other in virtual reality enhances the sense of social presence.

4.1.2.Communication and Interaction through Networking

Communication and interaction with others in virtual reality is very important component for social presence (Short, Williams and Christie, 1976 and Rettie, 2003). In our project, participants were able to interact and communicate with other participants by using a virtual object. Participants’ virtual body is rigid in the space to bump into most of virtual objects and environment. If a participant collides into a virtual object using their virtual body, the virtual object will bounce away. This action is not only seen by the participant, but other participants can also see this through Photon Networking, the object moves simultaneously in each participants’ head mounted display. This means that participants can see and collide with the same virtual object thus enabling them to interact and communicate with other participants. This project is not mono-player virtual experience, but one in which participants can share space and the movement of an object. Participants can react other participant’s action; for example, if a player moves a virtual object, you may try to respond to the action by moving it back. This report proposes that these actions can evoke communication and interaction with other players, and then participants’ sense of social presence may be also enhanced.

4.1.3.Synchronized 3D Recorded videos

[Figure 8] Actors are recorded by Brekel Pro Pointcloud v2 with a Kinect sensor.

[Figure 9] A recorded 3D video is animated in Virtual space.

Brekel Pro Pointcloud v2 is an application that enables the recording of 3D pointcloud videos by using a Kinect sensor, and export them as 3D model data (Figure 8). We recorded some scenes such as people chatting, someone just seating down and using a smartphone. Whilst each scene is roughly 30 seconds long video and has 12 frames per second, this is not exported as standard format video. Instead, frames are exported one by one as Obj. format data with texture, and then imported in Unity 3D and programmed to appear and, subsequently, disappear in 1/12 seconds. After a frame disappears, next frame will appear. To continue these appearance and disappearance makes participants to feel watching a video. The video is also synchronized in each participant’s display through Photon Networking. The PhotonAnimatorView is a component that allows participants to watch an animation or a video with other participants at the same time in different displays. Watching together at the same time creates a single timeline. If the video is not synchronized together, however, each participant experiences a different time line. Different timelines may decrease a sense of “being there with others”, or social presence, because sharing environment with other enhances sense of presence (Moskaliuk and Kimmerle, 2011). In reality, time is perceived to occur in one line, and by extension we by default share the same time with all other people. Therefore, synchronized video is very important factor to create an only time line in multiplayer virtual experience. The time line can enhance sense of presence, especially social presence, and sharing environment with others.

 

To sum up, Photon Networking Service enables participants to be with others in virtual environment. It also allows them to interact and communicate with others simultaneously, across the Internet. This means that participants not only share virtual space with other players but they can also have common time line by using synchronized video. By all watching same video at same time and interacting with each other through virtual objects, participant feel that they are truly ‘with’ someone in the virtual space. Ones recognition of others in virtual environment can be an evidence of existence of themselves (Heeter, 1992). Therefore, existence of other participants increases their mutual sense of “being there”. The multiplayer experience enhances not only social presence but also personal presence.

4.2.Avatar

4.2.1.Virtual Body

[Figure 10] Photogrammetry by Autodesk ReMake

We created virtual body using Autodesk ReMake, a photogrammetry program (Figure 10). Photogrammetry is an application that constructs a 3D model from photographs. Most current virtual experiences employ a 3D model which was constructed using 3D modelling software, such as 3Ds Max and Rhinoceros as an avatar. These applications are easy to manage with a 3D mesh model, however, it requires long time to construct a well-detailed 3D model. In contrast, a photogrammetry application requires only some photographs, and is able to construct well-detailed 3D models automatically. The quality of a 3D model depends on how many photographs are installed for Autodesk ReMake. We took between 100-120 photographs to a model each participant. Using less than 100 pictures, the application can recognize a model person and background clearly. More than 100 photographs enable the creation of clear well-detailed 3D models. As Casanueva and Blake (2001) pointed out, virtual body awareness enhances sense of personal presence, so using a well-detailed model is important for providing a strong sense of presence. Participants are more readily aware that “this is my body” by using well-detailed models. This awareness, and ownership, of a virtual body can lead to an enhanced sense of presence.

4.2.2.Captured Motion

[Figure 11]  Capturing motion from an actor by iPi MoCap

[Figure 12] Merging skeletal data with a virtual body

The way that the virtual body behaves within a virtual environment is also an important component in how plausible participants find their body to be. However, it is difficult that animate human motion due to the complexity of geometric and physical interactions (Silva, Abe and Popovic, 2008). Therefore, this project creates avatar’s actions from real human behavior by capturing an actor’s action. Firstly, we record an actor’s action as point cloud data by iPi Recorder 3 application and a Kinect 2 sensor (Figure 11). Then import this data into iPi MoCap Studio 3 application to transform this data to skeletal data. This application analyses the actor’s motion from recorded point cloud data by the iPi Recorder. Finally, this skeletal data is merged with an avatar (Figure 12). The avatar performs the action when the owner of the avatar commands. In this project, an avatar is controlled by only participant’s head position. If a participant’s head position moves on X and Z axes, his/her avatar act walking and move the same distance he/she moved in real world. If a participant’s head position moves down on Y axis, the avatar crouches down or stands up. The avatar performs natural human actions to follow the participants’ motion. By showing the avatar’s natural human-like action to each other, participants can perceive others in virtual world because their avatar emulates the behavior of the real world. This natural action may also stimulate their sense of presence (Held and Durlach, 1992).

 

 To conclude, avatars are not solely for increasing a participants’ sense of “being there” in multiplayer virtual experience, they also confirm their feeling of existence in virtual environment. Participants confirm their own existence in a virtual space when they have the ability to recognise others. Therefore, it is important what the virtual body looks like, and how the avatar behaves in virtual space. An avatar that created from a real human model and acts like a human can be recognized easily, because the avatar looks like us and acts like us. Well-detailed avatars can enhance not only sense of “being there” but also “being there with someone”.

 

4.3. Environment

4.3.1. Free walking in virtual environment

[Figure 13] Project Tango motion tracking system.

Locomotion is the most common issue in current VR experiences (Iwata, 1999). Most current VR equipment requires cables to connect a head mounted display to a computer in order to send data. Therefore, the length of the cables is a clear limitation to participants’ movement, therefore virtual reality participants are only available to walk around a finite area. Moreover, often VR equipment requires external sensors to detect participant movement. The range of sensors is also limited to detect just one user.

[Figure 14] The users walk around their physical environment, while they are in virtual space.

There is difficulty to move around freely in virtual reality. In order to avoid this, we employ Project Tango, which is a tablet devise developed by Google, as a head mounted display. This device is equipped with a motion tracking camera, a depth sensor and a RGB camera. These cameras and a sensor update the position and rotation of the device data every single second and track user’s motion (Keralia, Vyas and Deulkar, 2014). This enables participants to walk around freely without any external sensors. In our design, we place a virtual camera on an avatar’s head in the virtual environment. The virtual camera changes position and rotation depending on Project Tango’s motion in physical reality. The avatar is controlled by Project Tango; if Project Tango moves forward, the avatar walk forward the same distance. The participant sees the virtual environment from the avatar’s point of view while walking freely in physical world. According to Fieandt (2016), humans perceive space as the relationship between their body and the objects around them, thus gives them cues, such as depth and distance that are crucial to both movement and orienting in the environment. Because of this, we often acquire information about our surroundings by moving our head and eyes to get a different view of the world at each moment (Oliva, Park and Konkle, 2010). Therefore, participants can perceive virtual environment as space by walking around the space freely. They gain information about the environment from different positions and perspectives. Moving around as they would in reality, the participant should feel a sense of being in the virtual environment and therefore a sense of environmental presence.

4.3.2. 3D Scanned environment

[Figure 15] 3D scanned Saint James Garden.

[Figure 16] 3D scanned Durmmond Street.

In this project, we scanned a real environment using the FARD Focus 3D X 330 Laser Scanner. A 3D laser scanner that collects environmental point data around itself three dimensionally in 1 to 1 scale. By using this technology, we scanned Saint James Garden and Durmmond Street in Euston (Figure 15 and 16), and used the 3D data to generate the virtual environment. Participants were allowed walk around 1 to 1 scale virtual environment, and move in three dimensions. As Bennett (2008) pointed out, environmental presence is evoked by moving around virtual space similar to real life, therefore walking around on a 1-to-1 scale virtual environment reproduces a plausible relationship with the virtual surroundings. This may be a part of enhancement of environmental presence due to the fact that the 1-to-1 scale environment is similar to what we see in everyday life; plausible representation of a real environment makes participants to feel present in a space.

 

4.3.3. Interact with environment

Virtual objects allow participants to interact with their virtual environment and with other participants. Moving a virtual object provides participants with awareness of their virtual body, and, at the same time, a sense of existence of the virtual object within the virtual space. Participants feel sense of environmental presence when modify virtual environment (Sherdan, 1992). Ones influence on the virtual environment can enhance ones sense of environmental presence. In this project, virtual objects within an environment make clear a response when collided against; when a participant bumped into a virtual object, the object was knocked over or moved across the virtual space. This response can be taken as evidence that the object and environment is there with you in the virtual environment. Interaction between a participant and his/her environment can increase environmental presence and participant’s awareness of body in virtual space.

 

In short, Project Tango allows free movement around the virtual space without cables or external sensors. Participants of this project were able to view the virtual environment from different perspectives while walking freely around the 1-to-1 scale environment. Moreover, the participants were aware of their virtual body and of the environment by interacting with the virtual objects. As a result, the participants’ had a heightened sense of environmental presence, engaging with and understanding the virtual environment through the head mounted display alone.

5. Conclusion

Presence is a crucial and primitive feeling for participants to perceive a virtual environment as a space. The multiplayer experience has great potential to enhance players’ sense of presence and immersion into virtual environments. Multiplayer enables a shared experience with other players; sharing space and time mutually increases each individual participant’s sense of presence. “Palimpsest” is a high presence multiplayer virtual experience achieved through cloud networking. Participants accept their existence in virtual space through the recognition of other participants, and becoming aware of others’ existence within the virtual environment.

The sense of being with others in virtual environment enhances ones feeling of presence. Additionally, interaction with others and with the environment is an important contributing component to evoking a sense of presence. A participant may feel sense of social presence, personal presence and environmental presence by gaining a response from other or environment to your action. The response enhances ones sense of presence.

There may be alternative ways to enhance sense of presence in virtual environment. However, this report proposes that both free walking and multiplayer virtual experience are vital in for experiencing presence in a virtual space, they enhance the sense of “being in virtual environment”.

Verbal communication through Photon network service is a natural next step. The Photon network service in fact already allows voice transmission over the Internet, thus allowing face-to-face and verbal communication in a virtual space. Participants would be able see each other through their avatar and chat with others in the virtual space, further promoting participants sense of presence when they communicate with others in a virtual environment.

 

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