Saturday, August 23, 2008

GaCIT in Tampere, day 3.

In the morning Howell Istance of De Montford University, currently at University of Tampere, gave a very intersting lecture concerning gaze interaction, it was divided into three parts 1) games 2) mobile devices 3) stereoscopic displays

This is an area for gaze interaction which have a high potential and since the gaming industry has grown to be a hugh industy it may help to make eye trackers accessible/affordable. The development would be benificial for users with motor impairments. A couple of examples for implementations were then introduced. The first one was a first person shoother running on a XBOX360:
The experimental setup evaluation contained 10 repeated trials to look at learning (6 subjects). Three different configurations were used 1) gamepad controller moving and aiming (no gaze) 2) gamepad controller moving and gaze aiming and 3) gamepad controller moving forward only, gaze aiming and steering of the movement.
However, twice as many shots were fired that missed in the gaze condition which can be described as a "machine gun" approach. Noteworthy is that no filtering was applied to the gaze position.
Howell have conducted a analysis of common tasks in gaming, below is a representation of the amount of actions in the Guild Wars game. The two bars indicate 1) novices and 2) experienced users.

Controlling all of these different actions requires switching of task mode. This is very challenging considering only on input modality (gaze) with no method of "clicking".

There are several ways a gaze interface can be constructed. From a bottom up approach. First the position of gaze can be used to emulate the mouse cursor (on a system level) Second, a transparent overlay can be placed on top of the application. Third, a specific gaze interface can be developed (which has been my own approach) This requires a modification of the original application which is not always possible.

The Snap/Clutch interaction method developed by Stephen Vickers who is working with Howell operates on the system level to emulate the mouse. This allows for specific gaze gestures to be interpretated which is used to switch mode. For example a quick glace to the left of the screen will activate a left mouse button click mode. When a eye fixation is detected in a specific region a left mouse click will be issued to that area.

When this is applied to games such as World of Warcraft (demo) specific regions of the screen can be used to issue movement actions towards that direction. The image below illustrates these regions overlaid on the screen. When a fixation is issued in the A region an action to move towards that direction is issued to the game it self.

Stephen Vickers gaze driven World of Warcraft interface.

After lunch we had a hands-on session with the Snap/Clutch interaction method where eight Tobii eye trackers were used for a round multiplayer of WoW! Very different from a traditional mouse/keyboard setup and takes some time to get used to.

  • Istance, H.O.,Bates, R., Hyrskykari, A. and Vickers, S. Snap Clutch, a Moded Approach to Solving the Midas Touch Problem. Proceedings of the 2008 symposium on Eye Tracking Research & Applications; ETRA 2008. Savannah, GA. 26th-28th March 2008. Download
  • Bates, R., Istance, H.O., and Vickers, S. Gaze Interaction with Virtual On-Line Communities: Levelling the Playing Field for Disabled Users. Proceedings of the 4th Cambridge Workshop on Universal Access and Assistive Technology; CWUAAT 2008. University of Cambridge, 13th-16th April 2008. Download

The second part of the lecture concerned gaze interaction for mobile phones. This allows for ubiquitous computing where the eye tracker is integrated with a wearable display. As a new field it is surrounded with certain issues (stability, processing power, variation in lightning etc.) but all of which will be solved over time. The big question is what the "killer-application" will be. ( entertainment?) A researcher from Nokia attended the lecture and introduced a prototype system. Luckily I had the chance to visit their research department the following day to get a hands-on with their head mounted display with a integrated eye tracker (more on this in another post)

The third part was about stereoscopic displays which adds a third dimension (depth) to the traditional X and Y axis. There are several projects around the world working towards making this everyday reality. However, tracking the depth of gaze fixation is limited. The vergence (as seen by the distance between both pupils) eye movements are hard to measure when the distance to objects move above two meters.

Calculating convergence angles
d = 100 cm tan θ = 3.3 / 100; θ = 1.89 deg.
d = 200 cm tan θ = 3.3 / 200; θ = 0.96 deg.

Related papers on stereoscopic eye tracking:
The afternoon was spent with a guided tour around Tampere followed by a splendid dinner at a "viking" themed restaurant.

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