Leaving the body: transition between first and third person perspective in VR


When presented with multi-sensorial signals showing a consistent match between a virtual body and oneself real body through an HMD, a subject may experience the strong sense that the virtual body she sees belongs to her. We may refer to this phenomena as Virtual Body Illusion (VBI). The viewpoint (first or third person perspective 1PP/3PP) relative to the virtual body where this multi-sensorial congruency is experienced is an important factor to this feeling of ownership, which has been shown to be weaker when the virtual body is seen from outside (3PP). However, 3PP offers additional information to the subject concerning his surroundings and environment, compensating technological limitations of the display, namely the smaller than natural field of view.

Project Idea

We propose to compare 1PP, 3PP, and a mixed approach that will transit between 1PP and 3PP (which will be implemented by the student). We argue that the mixed approach may be nearly as effective as 1PP regarding the feeling of ownership, and present better performance than 1PP or 3PP alone by joining their strengths. More specifically, 1PP for manipulation and 3PP for quick visual search and virtual  body posture control .

Figure 1: (left) first and (center) third person viewpoints with nearly 90º of field of view. (right) Transition between viewports while preventing the camera from passing through the head of the virtual body.

The usual ways to measure body ownership are questionnaires (self-reported) and physiological response to a threat directed to the virtual body (impression that the virtual threat could hurt the subject own body).

Figure 2: Galvanic skin conductance sensor

The student will:

1. Implement an optimal perspective transition technique that avoids discontinuities to the experience (e.g. not going through walls or body parts).

2. Integrate a physiological measurement equipment (g.tech usbamp and arduino available), which will involve collecting physiological synchronized with events on the virtual environment.

3. Logging scripts are provided, but it is likely that they will have to be adapted to accommodate proposed measurements.

4. Conduct an experiment.

5. Analyze collected data.

The virtual body motion control platform will be provided.

Development framework:

The development of this project is based on the interactive game engine Unity 3D.


Head mounted display – Oculus Rift DK2;

Motion tracking – Phasespace / playstation move controllers

Physiological measurements – g.tech usbamp with galvanic skin response Sensor or heart rate monitoring.

The student will develop an Unity package to allow the easy integration of this functionality to any Unity project.


Programming (C# or Javascript Unity3D).


Ronan BOULIC (Ronan.boulic at epfl.ch   INJ141 )

Henrique GALVAN DEBARBA (henrique.galvandebarba at epfl.ch INJ139 )