Accurate Gaze Direction Measurements with Free Head Movement for Strabismus Angle Estimation.
ABSTRACT We present the Delft Assessment Instrument for Strabismus in Young children (DAISY) a device designed to measure angles of strabismus in young children fast and accurately. Daisy allows for unrestrained head movements by the mean of a triple camera vision system that simultaneously estimates the head rotation and the eye pose. The device combines two different methods to record bilateral eye position: corneal reflections (Purkinje images) and pupillary images. Detailed results are provided on three orthotropic subjects (age 25-27). Three different conditions were tested: (i) gaze ahead, (ii) gaze ahead with different head rotations and (iii) fixed head with different eye positions. Systematic errors occurred between subjects that need further study. The system reached sufficient accuracy to be applied for the measurement of angles of strabismus, almost independent from the head pose.
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ABSTRACT: This paper presents a general theory for the remote estimation of the point-of-gaze (POG) from the coordinates of the centers of the pupil and corneal reflections. Corneal reflections are produced by light sources that illuminate the eye and the centers of the pupil and corneal reflections are estimated in video images from one or more cameras. The general theory covers the full range of possible system configurations. Using one camera and one light source, the POG can be estimated only if the head is completely stationary. Using one camera and multiple light sources, the POG can be estimated with free head movements, following the completion of a multiple-point calibration procedure. When multiple cameras and multiple light sources are used, the POG can be estimated following a simple one-point calibration procedure. Experimental and simulation results suggest that the main sources of gaze estimation errors are the discrepancy between the shape of real corneas and the spherical corneal shape assumed in the general theory, and the noise in the estimation of the centers of the pupil and corneal reflections. A detailed example of a system that uses the general theory to estimate the POG on a computer screen is presented.IEEE Transactions on Biomedical Engineering 07/2006; DOI:10.1109/TBME.2005.863952 · 2.23 Impact Factor
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ABSTRACT: The author addresses the problem of parametric representation and estimation of complex planar curves in 2-D surfaces in 3-D, and nonplanar space curves in 3-D. Curves and surfaces can be defined either parametrically or implicitly, with the latter representation used here. A planar curve is the set of zeros of a smooth function of two variables x - y , a surface is the set of zeros of a smooth function of three variables x - y - z , and a space curve is the intersection of two surfaces, which are the set of zeros of two linearly independent smooth functions of three variables x - y - z For example, the surface of a complex object in 3-D can be represented as a subset of a single implicit surface, with similar results for planar and space curves. It is shown how this unified representation can be used for object recognition, object position estimation, and segmentation of objects into meaningful subobjects, that is, the detection of `interest regions' that are more complex than high curvature regions and, hence, more useful as features for object recognitionIEEE Transactions on Pattern Analysis and Machine Intelligence 12/1991; 13(11):1115-1138. DOI:10.1109/34.103273 · 5.69 Impact Factor
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ABSTRACT: We introduce a new method for computing the 3D position of an eye and its gaze direction from a single camera and at least two near infra-red light sources. The method is based on the theory of spherical optical surfaces and uses the Gullstrand model of the eye to estimate the positions of the center of the cornea and the center of the pupil in 3D. The direction of gaze can then be computed from the vector connecting these two points. The point of regard can also be computed from the intersection of the direction of gaze with an object in the scene. We have simulated this model using ray traced images of the eye, and obtained very promising results. The major contribution of this new technique over current eye tracking technology is that the system does not require to be calibrated with the user before each user session, and it allows for free head motion.Pattern Recognition, 2002. Proceedings. 16th International Conference on; 01/2002