Research On The Measurement Of Human Head Pose Based On Imaging Analysis Of Circular Target

Measurement of human head pose is an important research topic in the fields of machine visionand pattern recognition. The main research purpose is to measure the pose parameters of the head inthree-dimensional space. There are shortcomings such as complex equipments and huge computationsin the existing technologies of head pose measurement. Based on the photoelectronic informationmeasurement principle, a new measurement method of dynamic head pose based on monocular visionmeasurement and geometric target is proposed. The relation between the geometric target’s imagingand pose angles is obtained by analyzing the optical imaging of the geometric target which is fixed onthe head, and then the head pose parameters are calculated. The system of head pose measurementproposed in this paper can meet the expected effect by the experiments. The research in this paper hasproposed a new effective approach to make the head pose measurement system simplier and morepractical. The main research and innovations are as follows:(1) A measurement method of head pose using imaging analysis of circular target is proposed inthis paper. The measurement technology of head pose based on monocular vision measurement andgeometric target is proposed after analyzing the existing technologies of head pose measurement. Theadvantages and faults of two common geometric targets-sphere and circle, are studied in themeasurement of head pose and at last the circle is chosen as the additive geometric target. Thedesigning and installation of circular target are studied. The information of head pose can be measuredby analysing the imaging changes of circular target and two diameters marked on the circular target inthe camera image plane.(2) The computation methods of rotation angles of circular target based on the optical imaginganalysis are proposed. Based on the principle of camera optical imaging, the imagings of circulartarget are analyzed when the circular target and the camera are in different poses. And on these bases,the imaging changes of the two diameters are studied separately when the head does simple andcomplex motions. The computation methods of pitch angle, roll angle and yaw angle in simple andcomplex situations are proposed separately by the geometric derivation method.(3) A method of eliminating the pose duality of circular target based on imaging analysis ofdiameter is proposed. The imagings of the two diameters are extracted from the circular target images.The motion direction with respect to the initial position can be judged by analyzing the slopes of thetwo diameters’ imagings and the lengths of radii’s imagings. And then the pose of the circular targetcan be determined. This method can elimitate the pose duality which often occurs in the process ofcalculating the pose of circular target.(4) The processing method of circular target images in the circumstance of common opticalimaging is studied. The circular targer images are often with poor imaging quality when the head posemeasurement system works in the circumstance of common optical imaging. The processingprocedures of wavelet denosing, gray level transformation, histogram processing, and imagebinarization are proposed for the images with poor imaging quality. The quality of the image isimproved after the processing. And binary images of circular target are obtained.(5) The composition of the measurement system of head pose based on imaging analysis ofcircular target is studied. The software system of the measurement of head pose is also designed. Thedecision method of head’s initial position based on the diameters of the circular target is proposed. The method of distinguishing the two diameters based on the slopes of the diameters is also proposed.Experimental research is also done using the system we proposed in this paper. The fesiblity of thesystem is verified by simulated experiment and head experiment. The research in this paper is ofsignificant theoretical and practical value.