Human Spatial Vision

An human-evolved division, the roles of central and peripheral vision are different, allowing us to see with great acuity in the center area, and with a large field of view in the periphery. The fovea is the central part of the retina where detailed vision occurs. This small spot is covered by cones, the optical receptors responsible for color information. At the fovea spatial resolution is very high while in the periphery it is quite low, therefore the angle of the visual field that is perceived with color and high resolution is very small. For this reason, the eyes must be in constant movement to perceive a scene. However, although spatial resolution is high at the fovea, temporal resolution is not as good and so the eye has to stop frequently.

Vision is therefore characterized by rapid movements followed by long pauses. During the fast movements (know as saccadic movements), visual processing is blocked to avoid blurring (a phenomenon called saccadic masking). The other movements are known as fixation movements. Approximately 90% of viewing time is spent in fixations [1]. There is also another kind of movement known as smooth pursuits that are responsible for keeping track of objects in motion.

Eye Tracking Technology

Eye-tracking technology has been available for a long time. Today the most widely used devices are video-based and combine pupil/corneal reflection. Video-based trackers utilize relatively inexpensive cameras and image processing hardware to compute the point of fixation in real time [1]. The semispherical shape of the eye provides a stable reference point whose rotations can be used to detect the movement of the pupil center. These types of devices can be made at low cost and also can be non-invasive. Either the head is immobilized, or the device includes a head-tracking strategy, or the system itself is head mounted. These techniques always require a calibration session to map the relative motions of the eye sensed in a camera to absolute coordinates in a screen.

Eye Tracking and Art

Eye tracking has been used in the arts as a promissory way to modify the work of an artist according to the people looking at it [5]; it has also been used to study eye movement while drawing, as in the Camberwell College of Arts [6] or even as a plain tool like in the work of Jochem Hendricks [7]. Colaborative experiences in eye tracking have been limited to specific commercial studies. Eye tracking is considered as a feasible alternative to interactive games and is expected to be around as an standard interface in the future years [8]

REFERENCES

[1] Duchowski, Andrew. Eye tracking methodology theory and practice, Springer 2003.
[2] Scherffig Lasse, Gaze Based Image Retrieval in Contex, University of Bremen, 2005.
[3] Stanney, Kay. Handbook of virtual enviroments , Design Implementation and Application. CRC 2002.
[4] Cortazar, Julio. Las armas secretas -Las babas del diablo. 1959.
[5] Art+ com, De-Viewer project.1992
[6] Camberwell College of Arts, Drawing & Cognition. 1999.
[7] Hochem Hendriks, Eye drawings 1992-1993. [8] Science Daily.Eye Tracking Technology Poised To Be Next Trend To Immerse Gamers. 2006.