This paper presents a multi-camera system that performs face detection and pose estimation in real-time
and may be used for intelligent computing within a visual sensor network for surveillance or human-computer
interaction. The system consists of a Scene View Camera (SVC), which operates at a fixed
zoom level, and an Object View Camera (OVC), which continuously adjusts its zoom level to match
objects of interest. The SVC is set to survey the whole filed of view. Once a region has been identified
by the SVC as a potential object of interest, e.g. a face, the OVC zooms in to locate specific features. In
this system, face candidate regions are selected based on skin color and face detection is accomplished
using a Support Vector Machine classifier. The locations of the eyes and mouth are detected inside the
face region using neural network feature detectors. Pose estimation is performed based on a geometrical
model, where the head is modeled as a spherical object that rotates upon the vertical axis. The triangle
formed by the mouth and eyes defines a vertical plane that intersects the head sphere. By projecting the
eyes-mouth triangle onto a two dimensional viewing plane, equations were obtained that describe the
change in its angles as the yaw pose angle increases. These equations are then combined and used for
efficient pose estimation. The system achieves real-time performance for live video input. Testing results
assessing system performance are presented for both still images and video.
Gaze estimation is an important component of computer vision systems that monitor human activity for
surveillance, human-computer interaction, and various other applications including iris recognition. Gaze
estimation methods are particularly valuable when they are non-intrusive, do not require calibration, and
generalize well across users. This paper presents a novel eye model that is employed for efficiently
performing uncalibrated eye gaze estimation. The proposed eye model was constructed from a geometric
simplification of the eye and anthropometric data about eye feature sizes in order to circumvent the
requirement of calibration procedures for each individual user. The positions of the two eye corners and
the midpupil, the distance between the two eye corners, and the radius of the eye sphere are required for
gaze angle calculation. The locations of the eye corners and midpupil are estimated via processing
following eye detection, and the remaining parameters are obtained from anthropometric data. This eye
model is easily extended to estimating eye gaze under variable head pose. The eye model was tested on
still images of subjects at frontal pose (0o) and side pose (34o). An upper bound of the model's
performance was obtained by manually selecting the eye feature locations. The resulting average absolute
error was 2.98o for frontal pose and 2.87o for side pose. The error was consistent across subjects, which
indicates that good generalization was obtained. This level of performance compares well with other gaze
estimation systems that utilize a calibration procedure to measure eye features.
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