Tag Archives: colocation

20. Colocation and the Oculus Rift

May 16, 2016 admin

In post 18. Interactive Props and Physics it was noted “Colocation issues are the result of the difficulty in perceiving where the character is in three dimensional space due to the lack of depth perception.”

In this enactment the Oculus Rift VR headset is used as a means of ascertaining whether the added depth perception of the stereoscopic rendering of the Unity scene might assist in enabling a perfomer to locate the virtual props in 3D space.

Three enactments were carried out, two with the rendered viewpoint from the camera located from the audience perspective and one from the first person perspective typically used in VR and gaming.

The video below is a mobile phone recording of a computer monitor rendering the Unity scene in real time. The computer uses an i7 processor and a relatively powerful Nvidia GT 720 graphics card to deliver the stereoscopic rendering to the Oculus Rift. Though the system is able to support the new Kinect v2, the older Kinect was used in order to maintain continuity with previous enactments.

In the first enactment myself and one of the previous performers carried out the task of knocking the book off the table. We both felt that the task was much easier to accomplish with the stereoscopic depth enabling one to easily judge the position of the avatars hand in relationship to the virtual book.

Kinect tracking errors made bending the arm and precise control of the hand a little problematic. The task was felt to be much easier to achieve than previous enactments using the monoscopic video camera perspective as it was possible to clearly see where the virtual hand was, even if when it was ‘misbehaving’.

However with the added depth perception a new issue came to be highlighted that was previously unnoticed, that of difficulties in knowing front from back. When one moves ones hand forward it moves away from you, whilst when viewed from the camera perspective the hand moves nearer to the camera, the opposite direction to which one is used to. This effect parallels the left right reversal of a mirror in comparison to the camera view. In both cases through practice it is possible to become accustomed to the depth reversal and lack of mirror reversal, though at first one finds oneself moving in the opposite direction, or using the opposite limb, It is possible to technically produce a mirror reversal, but a depth reversal was felt to be more problematic. A simpler solution, easily achievable using VR was to give the performer the same first person perspective as one is normally used to – seeing the scene from the viewpoint of the avatar. In the video, the third enactment carried out by myself demonstrates this perspective.

Due to time constraints it was not possible to test this enactment with the external participant. However despite the incredibly immersive qualities of the first person perspective, I felt there are some serious problems resulting from this viewpoint.

Firstly I felt a very strange out of the body experience looking down at a virtual body that was not mine, in addition my virtual limbs and my height were completely different to my own and this produced a strong sense of disorientation. Perhaps a male body of similar height and dimensions to my own might have felt more familiar.

The task of knocking the book over felt extremely easy as I could see my virtual hand in relationship to the book from a familiar first person perspective. Despite Kinect tracking issues, it was possible to correct the position of the hand and ultimately knocking the book over was easy to achieve. Both the issues of depth and mirror reversal were removed using this perspective.

However walking and moving in the scene resulted in a strong degree of vertigo and dizziness. For the first time I experienced “VR motion sickness” and nearly fell over. It was extremely unpleasant!

Further, after taking the headset off, for some minutes I still felt disorientated, somewhat dizzy and a little out of touch with reality.
Although the first person perspective should have felt the most natural, it also produced disturbing side effects which if not rectified would make the first person VR perspective unusable if not hazardous in a live performance context.

The feelings of vertigo and motion sickness may well have been exaggerated due to Kinect tracking issues, with the avatar body moving haphazardly resulting in a disconnect between the viewpoint rendered by the avatars perspective and that of where my real head thought it was.

Two further practical considerations are: i) the VR headset is tethered by two cables making it difficult to move feely and safely and ii) the headset being enclosed felt somewhat hot after a short period of time. Light, ‘breathable’ wireless VR headsets may solve these problems, but the effects of vertigo resulting from the first person perspective whilst moving in 3D space and feeling as if one is in another body are perhaps more problematic.

The simplest solution, though still with the depth reversal issue, is removing the VR tracking and to create a fixed virtual camera giving the audience perspective, parallel to the previous methodology of relaying the audience perspective through a video camera mounted on a tripod.

Before dismissing the VR first person perspective being the sole cause of motion sickness, it is planned that a further test be carried out using the more accurate Kinect v2 with a virtual body of proportions similar to my own. It is envisaged that the Kinect v2 would result in a more stable first person perspective and with a more familiar viewpoint as one I am used to with my natural body.

In addition other gaming like perspectives might also be tried, the third person perspective for instance, with a virtual camera located just above and behind the avatar.

A key realisation is that the performers perspective need not necessarily be that of the audience, that the iMorphia system might render two (or possibly more) perspectives – one for the audience – the projected scene, and one for the performer. The projected scene being designed to produce the appropriate suspension of disbelief for the audience, whilst the performer’s perspective designed to enable the performer to perform efficiently such that the audience believes the performer to be immersed and present in the virtual scene.

Research Blog

19. Interaction Workshop

March 8, 2016 admin

A workshop involving two performers was carried out in order to re-evaluate the performative notions of participation and navigation (Dixon 2007), described in post 15. Navigation.

Previously a series of auto-ethnographic enactments (documented in posts August-December 2015) provided some initial feedback on participation and navigation with iMorphia . It was interesting to observe the enactments as a witness rather than a participant and to see if the performers might experience similar problems and effects as I had.

Participation
The first study was of participation – with the performer interacting with virtual props. Here the performer was given two tasks, first to try and knock the book off the table, then to knock over the virtual furniture, a table and a chair.

The first task involving the book proved extremely difficult, with both performers confirming the same problem as I had encountered, namely knowing where the virtual characters hand was in relationship to ones own real body. This is a result of a discrepancy in collocation between the real and the virtual body compounded by a lack of three dimensional or tactile feedback. One performer commenting “it makes me realise how much I depend on touch” underlining how important tactile feedback is when we reach for and grasp an object.

The second task of knocking the furniture was accomplished easily by by both performers and prompted gestures and exclamations of satisfaction and great pleasure!

In both cases, due to the lack of mirroring in the visual feedback, initially both performers tended to either reach out with the wrong arm or move in the wrong direction when attempting to move towards or interact with a virtual prop. This left/right confusion has been noted in previous tests as we are so used to seeing ourselves in a mirror that we automatically compensate for the horizontal left right reversal.

An experiment carried out in June 2015 confirmed that a mirror image of the video would produce the familiar inversion we are used to seeing in a mirror and performers did not experience the left/right confusion. It was observed that the mirroring problem appeared to become more acute when given a task to perform involving reaching out or moving towards a virtual object.

Navigation
The second study was of navigation through a large virtual set using voice commands and body orientation. The performer can look around by saying “Look” then using their body orientation to rotate the viewpoint. “Forward” would take the viewpoint forward into the scene whilst “Backward” would make the scene retreat as the character walks out of the scene towards the audience. Control of the characters direction is again through body orientation. “Stop” makes the character stationary.

Two tests were carried out, one with the added animation of the character walking when moving, the other without the additional animation. Both performers remarking how the additional animation made them feel more involved and embodied within the scene.

Embodiment became a topic of conversation with both performers commenting on how landmarks became familiar after a short amount of time and how this memory added to their sense of being there.

The notions of avatar/player relationship, embodiment, interaction, memory and visual appearance are discussed in depth in the literature on game studies and is an area I shall be drawing upon in a deeper written analysis in due course.

Finally we discussed how two people might be embodied and interact with the enactments of participation and navigation. Participation with props was felt to be easier, whilst navigation might prove problematic, as one person has to decide and controls where to go.

A prototype two performer participation scene comprising two large blocks was tested but due to Unity problems and lack of time this was not fully realised. The idea being to enable two performers to work together to lift and place large cubes so as to construct a tower, rather like a children’s toy wood brick set.

Navigation with two performers is more problematic, even if additional performers are embodied as virtual characters , they would have to move collectively with the leader, the one who is controlling the navigation. However this might be extended to allow characters to move around a virtual set once a goal is reached or perhaps navigational control might be handed from one participant to another.

It was also observed that performers tended to lose a sense of which way they were facing during navigation. This is possibly due to two reasons – the focus on steering during navigation such that the body has to rotate more and the lack of clear visual feedback as to which way the characters body is facing, especially during moments of occlusion when the character moves through scenery such as undergrowth.

These issues of real space/virtual space colocation, performer feedback of body location and orientation in real space would need to be addressed if iMorphia were to be used in a live performance.

Research Blog

18. Interactive Props and Physics

December 6, 2015 admin 2 Comments

The video documentation below illustrates an enactment of iMorphia with props imbued with physics. The addition of rigid body colliders and physical materials to the props and the limbs of the avatar enables Unity to simulate in real time the physical collision of objects and the effects of gravity, weight and friction.

The physics simulation adds a degree of believability to the scene, as the character attempts to interact with the book and chair. The difficulty of control in attempting to make the character interact with the virtual props is evident, resulting in a somewhat comic effect as objects are accidentally knocked over.

Interaction with the physics imbued props produced unpredictable responses to performance participation, resulting in a dialogue between the virtual props and the performer. These participatory responses suggest that physics imbued props produce a greater sense of engagement through enhancing the suspension of disbelief – the virtual props appear more believable and realistic than those that not imbued with physics.

This enactment once again highlights the problem of colocation between the performer, the projected character and the virtual props. Colocation issues are the result of the difficulty in perceiving where the character is in three dimensional space due to the lack of depth perception. There are also navigational problems resulting from an incongruity between the mapping of the position of the performers body and limbs in real space and those of the virtual characters avatar in virtual space.

Research Blog

17. Interactive Props

November 10, 2015 admin

In this experimental enactment I created a minimalist stage like set consisting of a chair and a table on which rests a book.

props2

The video below illustrates some of the issues and problems associated with navigating the set and possible interactions between the projected character and the virtual objects.

Problems and issues:

1. Projected body mask and perspective
As the performer moves away from the kinect, the virtual character shrinks in size such that the projected body mask no longer matches the performer. Additional scripting to control the size of the avatar or altering the code in the camera script might compensate for these problems, though there may be issues associated with the differences between movements and perceived perspectives in the real and virtual spaces.

2. Colocation and feedback
The lack of three dimensional feedback in the video glasses results in the performer being unable to determine where the virtual character is in relationship to the virtual objects and thereby unable to successfully engage with the virtual objects in the scene.

3. Real/virtual interactions
There are issues associated with interactions between the virtual character and the virtual objects. In this demonstration objects can pass through each other. In the Unity games engine it is possible to add physical characteristics so that objects can push against each other, but how might this work? Can the table be pushed or should the character be stopped from moving? What are the appropriate physical dynamics between objects and characters? Should there be additional feedback, perhaps in the form of audio to represent tactile feedback when a character comes into contact with an object?

How might the book be picked up or dropped? Could the book be handed to another virtual character?

Rather than trying to create a realistic world where objects and characters behave and interact ‘normally’ might it be more appropriate and perhaps easier to go around the problems highlighted above and create surreal scenarios that do not mimic reality?

Research Blog

16. Participation, Conversation, Collaboration

October 14, 2015 admin

Since the last enactment exploring navigation, I have been looking to implement performative interaction with virtual objects – the theatrical equivalent of props – in order to facilitate Dixon’s notions of participation, conversation and collaboration.

I envisaged implementing a system that would enable two performers to interact with virtual props imbued with real world physical characteristics. This would then give rise to a variety of interactive scenarios – a virtual character might for instance choose and place a hat on the head of the other virtual character, pick up and place a glass onto a shelf or table, drop the glass such that it breaks, or collaboratively create or knock down a construction of virtual boxes. These types of scenarios are common in computer gaming, the challenge here however, would be to implement the human computer interfacing necessary to support natural unencumbered performative interaction.

This ambition raises a number of technical challenges, including the implementation of what is likely to be non-trivial scripting and the requirement of fast, accurate body and gesture tracking, perhaps using the Kinect 1.
There are also technical issues associated with the colocation of the performer and the virtual objects and the need for 3D visual feedback to the performer. These problems were encountered in the improvisation enactment with a virtual ball and discussed in section “3. Depth and Interaction” in post 14. Improvisation Workshop.

The challenges associated with implementing real world interaction with virtual 3D objects are currently being met by Microsoft Research in their investigations of augmented reality through prototype systems such as Mano-a-Mano and their latest project, the Hololens.

“Mano-a-Mano is a unique spatial augmented reality system that combines dynamic projection mapping, multiple perspective views and device-less interaction to support face-to-face, or dyadic, interaction with 3D virtual objects.”

“Microsoft HoloLens understands your gestures, gaze, and voice, enabling you to interact in the most natural way possible”

Reviews of the Hololens suggest natural interaction with the virtual using the body, gesture and voice is problematic, with issues of lag, and the misreading of gestures, similar to the problems I encountered during 15. Navigation.

“While voice controls worked, there was a lag between giving them and the hologram executing them. I had to say, “Let it roll!” to roll my spheres down the slides, and there was a one second or so pause before they took a tumble. It wasn’t major, but was enough to make me feel like I should repeat the command.

Gesture control was the hardest to get right, even though my gesture control was limited to a one-fingered downward swipe”

(TechRadar 6/10/2015)

During today’s supervision meeting it was suggested that instead of trying to achieve the interactive fidelity I have been envisaging, which is likely to be technically challenging, that I work around the problem and exploit the limitations of what is possible using the current iMorphia system.

One suggestion was that of implementing a moving virtual wall which the performer has to interact with or respond to. This raises issues of how the virtual wall responds to or effects the virtual performer and then how the real performer responds. Is it a solid wall, can it pass through the virtual performer? Other real world physical characteristics might imbued in the virtual prop such as weight or lightness; leading to further performative interactions between real performer, virtual performer and virtual object.

KINECTIC

Tag Archives: colocation

20. Colocation and the Oculus Rift

19. Interaction Workshop

18. Interactive Props and Physics

17. Interactive Props

16. Participation, Conversation, Collaboration

Performative Interaction and Embodiment on an Augmented Stage