Tag Archives: navigation

19. Interaction Workshop

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.

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.


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 co-location, 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.

18. Interactive Props and Physics

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 and a degree of improvisation – for example arms raised in frustration and the kicking over of the chair. 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 co-location between the performer, the projected character and the virtual props. Co-location 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.

17. Interactive Props

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



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. Co-location 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?

16. Participation, Conversation, Collaboration

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 co-location 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.



15. Navigation

At the last workshop, a number of participants expressed the desire to be able to  enter into the virtual scene. This would be difficult in the 2D environment of PopUpPlay but totally feasible with iMorphia, implemented in the 3D Games Engine, Unity.

Frank Abbott, one of the participants, suggested the idea of architectural  landscape navigation, with a guide acting as a story teller and that the short story “The Domain of Arnheim” by Edgar Allen Poe might be inspirational  in developing navigation within iMorphia.

The discussion continued with recollections of the effectiveness of early narrative  and navigational driven computer games such as “Myst”.

Steve Dixon in “Digital Performance ” suggests four types of performative interaction  with technology (Dixon, 2007, p. 563):

  1. Navigation
  2. Participation
  3. Conversation
  4. Collaboration.

The categories are ordered in terms of complexity and depth of interaction, 1 being the simplest and 4 the more complex. Navigation is where the performer steers through the content,  this might be spatially as in a video game or via hyper links. Participation is where the performer undergoes an exchange with the medium. Conversation is where the performer and the medium undergo a back and forth dialogue. Collaboration is where participants and media interact produce surprising outcomes, as in improvisation.

It is with these ideas I began investigating the possibility of realising performative navigation in iMorphia. First I added a three dimensional landscape, ‘Tropical Paradise’ an asset supplied with an early version  of Unity (v2.6, 2010).


Some work was required fixing shaders and scripts in order to make the asset run with the later version of Unity (v4.2, 2013) I was using.

I then began implementing control scripts that would enable a performer to navigate the landscape, the intention being to make navigation feel natural, enabling the unencumbered performer to seamlessly move from  a conversational mode to a navigational one. Using the Kinect Extras package I explored combinations of spatial location, body movement, gesture and voice.

The following three videos document these developments. The first video demonstrates the use of gesture and spatial location , the second body orientation combined with  gesture and voice and the third voice and body orientation with additional animation to enhance the illusion that the character is walking rather than floating through the environments.

Video 1: Gesture Control

Gestures: left hand out = look left, right hand out = look right, hand away from body = move forwards, hand pulled in = move backwards, both  hands down = stop.

Step left or right = pan left/right.

The use of gesture to control the navigation proved problematic, it was actually very difficult to follow a path in the 3D world, and gestures were sometimes incorrectly recognised (or performed) resulting in navigational difficulties where a view gesture acted as a movement command or vice versa.

In addition the front view of the character did not marry well with the character moving into the landscape.

Further scripting and upgrading of the Kinect assets  and Unity to v4.6 enabled the successful implementation of a combination of speech recognition, body and gesture control.

Video 2: Body Orientation, Gesture and Speech Control

Here the gesture of both hands out activates view control, where body orientation controls the view. This was far more successful than the previous version and the following of a path proved much easier.

Separating the movement control to voice activation ( “forward”, “back”, “stop”) helped in removing gestural confusion, however voice recognition delays resulted in overshooting when one wanted to stop.

The rotation of the avatar to face the direction of movement produced a greater sense of believability that the character is moving through a landscape. The addition of a walking movement would enhance this further – this is demonstrated in the third video.

Video 3: Body orientation and Speech Control

The arms out gesture felt a little contrived and so in the third demonstration video I added the voice command “look” to activate the change of view.

Realising the demonstrations took a surprising amount of work, with much time spent scripting and dealing with setbacks and pitfalls due to Unity crashes and compatibility issues between differing versions of assets and Unity. The Unity Kinect SDK and Kinect Extras assets proved invaluable in realising these demonstrations, whilst the Unity forums provided insight, support and help when working with quaternions, transforms, cameras, animations, game objects and the sharing of scripting variables. At some point in the future I intend to document the techniques I used to create the demonstrations.

There is much room for improvement and creating the demonstrations has led to speculation as to what an ideal form of performative interaction might be for navigational control.

For instance a more natural form of gestural recognition than voice control would be to recognise the dynamic gestures that correspond to walking  forwards and backwards. According to the literature this is technically feasible, using  for instance Neural Networks  or Dynamic Time Warping, but these complex techniques are felt to be way beyond the scope of this research.

The object here is not to produce fully working robust solutions, instead the process of producing the demonstrations act as proof of concept and identify the problems and issues associated with live performance, navigation and control. The enactment and performance to camera serves to test out theory through practise and raises further questions and challenges.

Further Questions

How might navigation work with two performers?

Is the landscape too open and might it be better if constrained via fences, walls etc?

How might navigation differ between a large outside space and a smaller inside one, such as a room?

How might the landscape be used as a narrative device?

What are the differences between a gaming model for navigation  where the player(s) are generally seated looking at a screen using a mouse/keyboard/controller and a theatrical model with free movement of one or more unencumbered performers on a stage?

What are the resulting problems and issues associated with navigation and the perspective of performers and audience ?