Analysis of Virtual Reality Application: Tilt Brush

.Abstract

Virtual Reality Applications can be critically analyzed using the Virtual Subjectiveness (Parés & Parés, 2006) model. It is a key element in the user-experience relationship and makes a connection between the user, the virtual environment and the virtual reality experience. Using this tool, we can get a base from which to design and analyze VR applications. VR is often mistaken by the technology and not as the medium of transmitting information. We also try to critically analyze how well the information is communicated.

.Author Keywords

Interaction, Virtual Reality, Virtual Subjectiveness, Applications, Tilt Brush, Sketching, Painting

.Introduction

Virtual Reality has been defined in different ways but one of the essential features of an AMVR application is the real time generation of stimuli.

One of the first models proposed for virtual environments was defined by S.R.Ellis and another attempt was defined by Latta and Oberg ( Latta & Oberg, 1994, IEEE Computer Graphics & Applications, 14, 23–29 ). However, both models were incomplete and they were defining the virtual environment in the first case, or in the second case, it was focused more on the user experience. None of them managed to deliver the whole story or the bigger picture.

As we mentioned before and as Giuseppe Riva mentioned in 1999 in his paper Virtual reality as a communication tool, VR is confused with the technology per se, for instance with the head mounted display.

The goal of the Virtual Subjectiveness model is firstly to offer a view on Virtual Reality as a communication medium and not just as the technology behind. Secondly, it can help detect the misuse of the medium for as a sensationalist instrument.

We chose Tilt Brush, an awarded virtual reality application as a subject for our critical endeavor.

4. Tilt Brush

Tiltbrush (Hackett & Skillman, 2014) is announced by its authors as a virtual reality application that is able to create paintings in 3D in a virtual space, through a mouse and a keyboard and visualize the actions with a virtual reality visor as the Oculus Rift (Oculus VR, 2015).

The application allows the user to use three dimensional and animated brushes strokes with different kinds of ink, with the opportunity to create new ones with special effects such as light, stars or

smoke, inclusive music and sound reactive brushes. After creating the drawing it is possible to export and share the creation to GIF or to a especial visualizer to be

able to be an spectator of the artworks creating process and to observe the drawing from diverse angles in the virtual environment with tools as Google Cardboard (Google, 2014

4. Tiltbrush as an AMVR Experience

Tiltbrush is announced as a Virtual Reality experience because it allows the users to create and visualize drawings in a virtual environment. The interaction is through the keyboard and the mouse, and the observation is mediated by a head mounted display. This gives the user the possibility of generating and observing the artworks in the virtual environment. Through the movement of the plans is possible to do drawings in 2D pans and then make a manipulation of the plan to rotate the painting in any direction.

The authors of this virtual experience define it as virtual reality with the base of the observance of a virtual environment and the power to make modifications in it. They fully exploit the virtual environment by letting the user play with unusual textures and “fabrics”. For example, you can paint with light or with metallic building blocks.

Figure 2. 3D drawing of a cat in the Tiltbrush virtual world

3. Tilt Brush Virtual Subjectiveness

We will describe the application “Tiltbrush” according to the elements of its Virtual Reality. To achieve this we will follow the Virtual Subjectiveness model (Parés & Parés, 2006), that make use of four different elements: Physical Interfaces, Logical Interface, Mappings, and the Behavior of the Logical Interface.

The virtual subjectiveness defines the whole experience that the user will have in the virtual environment. Is the way in that the user is allowed to understand the things that are around him and how they work. Is the whole composition of the 4 elements, how they interact between them and how the user develops in the experience. They effect is created in the cognitive level, by this definition the user doesn’t have a relationship with the physical inputs or the physical outputs, the relationship is made directly to the virtual environment. A change in some of the elements won’t change the virtual environment, it will change the complete experience.

In this application the virtual environment is the scene where the drawing is taking place, the virtual subjectiveness consist in the place of the user in this scene and the experience is created in the cognitive level given by the configuration and assembly of the next particular elements.

Figure 3. Virtual Environment of the application. Retrieved from www.facebook.com/Tiltbrush

3.1 Physical Interfaces

In Tilt Brush the user has different different ways of interaction with the 3D environment. The most important is the possibility of drawing in different planes and move the position of the planes, secondly, the user can explore the environment and admire, contemplate the created artwork.

To achieve the previous objectives there are three physical interfaces: two of input and one of input and output. Let’s focus in the input physical interfaces: Keyboard, mouse, and Head mounted display (Oculus Rift or Google Cardboard) The keyboard is the user’s way to control the planes in which the drawing is taking place; using it is necessary to control the movement of the objects in the virtual environment. In second place we have the mouse that is the input used to make the strokes in the virtual canvas. These two previous interfaces are potentially replaceable for other kinds of tools like a Leap Motion for example; that is the future approach that the authors propose but not implemented yet because the wanted to “address the lowest common denominator of controls” (Flaherty, 2014)

For the visualization of the scene the information of the position and orientation of the head is retrieved from the head mounted display and reflect in the virtual environment as a way to change the point of view of the user in the scene. The same head mounted display is used as the only output physical interface to show the image.

Figure 4. Person using the Tiltbrush application with the keyboard and the Oculus Rift. Retrieved from www.facebook.com/Tiltbrush

3.2 Logical Interface

The logical interface defines the kind of view, the direction of the viewing, the expression of the physical inputs interfaces and so the representation of the character in the virtual environment.

In the Tilt Brush app the logical interface is the cursor from the screen, and when you select a brush is the brush itself. It’s inside the virtual environment that is the scene where the drawing is taking place surrounded to the buttons and different options and has behaviors able to interact and manipulate the virtual system.

.3.3 Potential Mappings

When we speak about the mappings we are expressing about the sensation of the user about how are related his interaction with the physical interfaces reflected in the logical interface, is the

relationship of the physical actions in the virtual world. The way in which a mapping is created can affect and change completely the experience and the self-understanding of the user in the environment. Tiltbrush has a direct mapping 1:1 between the movement of the head and the point of view of the scene and the movements of the mouse into the drawings realized in the virtual canvas. The mapping could be modified by changing the configuration of the mouse to be able to encompass a higher distance in the virtual environment with a smaller movement of the mouse and consequently create larger drawings with smaller movements of the mouse.

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.Behaviors of the Logical InterfaceThe behavior is the relationship between the logical interface and the elements and objects in the scene of the virtual environment. The behaviors are the way in which the user can interact with the elements of the virtual environment through the logical interface.

In Tiltbrush the user can make strokes in the virtual canvas modifying the scene through the logical interface but only inside of the canvas, he can also touch and select different brushes to use inside the virtual reality. About the viewing of the scene, the user can change his view angle of the scene but he can’t move to explore it.

10. Levels of interaction

According to the Virtual Subjectiveness framework, the user can have different types of interaction in the virtual environment. There is the exploration, the actual navigation (walking, flying, looking around). The second one is the manipulation - the user can operate within the environment and has agency, and the third one, contribution - the user can modify the environment and specific objects.

Tilt Brush has a contributive type of interaction. You can use different tools (brushes) to create new content. You generate and manipulate the content and create animated GIF's that you can share within the community. A very interesting feature, data-driven brushes, that allow users to create their own brushes (volumetric, refraction, light and even music reactive brushes). We can conclude there are many ways in which you contribute to the virtual environment.

Regarding the user provided capabilities, there are human capabilities used in the experience. The

parameters required from the user are the input coming from the keyboard and the mouse. In the close future, the developers will make possible other type of physical inputs like the movements of fingers using LeapMotion and Kinect. The logical interface of this system is the cursor of the mouse when you operate within the selection or options menu and the chosen brush, when you draw/paint. The virtual objects necessary for the interaction is the control panel and the grid that you draw on. It is very clear what do you have to do and what is the goal of this app. The first advantage would be that the user is probably already used to drawing environments for 2D like paint or Photoshop, so the designers had an easier job.

11. Interaction design. Content-driven versus Interaction-driven interaction.

The content driven design focuses more on the subject of the application while the interaction driven design focuses more on collaboration and the relationships between the users and the environment. The different types of interaction can be : user-user, user-environment, environment - environment and user-environment.-environment-user

In this case we can talk about an content driven design. Being an application created for a head mounted display, it can be accessed from anywhere in the world so it doesn't depend on the location. Why is it content driven? First of all the message is quite clear, it is about sketching and the novelty consists in the fact that app allows you to manipulate through rotation, flip and reposition a grid that operates as a stationary plane in space. By switching the plane ( horizontal or vertical) you have liberty of expression. The sketching tool was intended to be, as one of the developers declared : “An expression tool, not a precision tool”. “We want users to create images easily, quickly, and share them in ways that make sense with VR”.

We can say that there is definitely user-environment interaction but there is no multi user experience. The only way that you can interact with other users is uploading you work, in a form of a animated GIF and seeing other users' work.

Ellis in 1991, defined optimal design as :”A well designed human-machine interface affords the user an efficient and effortless flow of information between the device and its human operator.” Also he states that a well designed application should decrease the adaptation period with the interface and the tools. From this point of view, Tilt Brush seems quite intuitive and user-friendly.

12.Critical Analysis

Tilt Brush offers a virtual reality experience in a virtual environment generated by a personal computer and mediated by a head mounted display. The difference between a virtual environment and the virtual reality is that the environment is represented by structures, parameters and functions and it was defined by Ellis as being the sum of the content, the geometry and the dynamics. On the other hand, the virtual reality is the real- time experience the user can have.

A specific feature of a virtual reality application is that the interaction with digital stimuli is generated in real time (Parés & Parés, 2006). Another characteristic of the virtual reality is depicted by Grigore Burdea and Philippe Coiffet, in their book Virtual Reality Technology and it is the “real time interactivity” Painting and drawing is done in real time in this case, so it successfully fits into this description. The user sees the objects that he draws change on the screen in response to his input.

4. Is it adequate?

It is the most adequate model for the desired end result, as it is meant to be a virtual reality sketching application. Choosing a virtual environment as a medium for Tilt Brush is fully justified. The most attractive part of this application is the idea of drawing/sculpting with light and unusual fabrics and textures. It is not officially released yet, so it is difficult to say if there is room for improvement. We can conclude that Tilt Brush follows the Virtual Subjectiveness framework.

References

Flaherty, J. (2014). A WILD LOOK AT WHAT IT’S LIKE TO PAINT INSIDE AN OCULUS RIFT. Retrieved March 10, 2015, from http://www.wired.com/2014/11/tilt-brush-could-be-photoshop-for-the-oculus-rift-era/

Google. (2014). Google Cardboard. Retrieved from http://www.google.com/get/cardboard/

Hackett & Skillman. (2014). Tiltbrush. Retrieved from http://www.tiltbrush.com/

Oculus VR. (2015). Oculus Rift. Retrieved from https://www.oculus.com/

Parés, N., & Parés, R. (2006). Towards a Model for a Virtual Reality Experience: The Virtual Subjectiveness. Presence: Teleoperators and Virtual Environments, 15(5), 524–538. doi:10.1162/pres.15.5.524

Grigore, C. B., & Philippe, C. (2003). Virtual reality

technology. by John Wiley & Sons.

Ellis, S. R. (1995). Virtual environments and

environmental instruments.Simulated and virtual

realities: Elements of perception, 85-101.

Riva, G. (1999). Virtual reality as communication tool: A sociocognitive analysis. Presence: Teleoperators and Virtual Environments, 8(4), 462-468.