Depth Camera Photogrammetry System For EEG Electrode

EEG(electroencephalogram)provides a great help for clinical doctors in the diagnosis of mental disorders.It has irreplaceable value particularly in the diagnosis of epilepsy.Determination of the position of brain source is an essential part of EEG diagnosis,it is important to estimating the positions of EEG electrodes.During the past two decades,researchers have proposed many kinds of methods and solutions to locate the positions of EEG measuring electrodes.Among them,photogrammetry method is the most popular one that is fast,convenient and stability.However,speed,cost,accuracy and convenience always cannot be balanced in practical application for the photogrammetry method.Ensuring the high efficiency and accuracy always results in high cost and complex.Aiming to solve these problems,this paper proposes a novel depth camera photogrammetry system for EEG Electrode.The main contributions are listed as following.Firstly,a novel depth camera photogrammetry system for EEG Electrode is presented.In this paper,the data acquisition device uses a color camera combined with depth sensor as a unit scheme.The unit can directly obtain scene's 3D information;therefore,the method can calculate the 3D location of EEG electrode in each single view.In order to obtain all of EEG electrodes,this paper captures data in five different views.Secondly,a transformation method based on point cloud for color camera and depth sensor calibration is proposed.Traditional calibration method used amplitude figure as a data source for calibration,but the distortion amplitude figure could cause the inaccurate calibration result.To remedy this,this paper utilizes the precise point cloud as a data source for calibration,and designs a 2.5D calibration plate.Thirdly,an EEG electrode automatic detection algorithm for real electrode cap and electrode as well as an electrodes registration algorithm is proposed.This paper proposes a method based on threshold value of region for automatic detection algorithm.This algorithm can be used for automatic precise detection of electrodes,and filters out the noise by just selecting region of interest containing electrode point.Then we use SVD algorithm to calculate the angleconversion relationship,finally convert all the electrodes to the same coordinates.Fourthly,a system based on Matlab platform for Depth Camera Photogrammetry System for EEG Electrode is designed and implemented.It includes GUI design and the implementation of the corresponding functions.The system can be used to read and display the image and 3D point cloud.Besides,it implements the calibration of color Camera and depth sensor and EEG electrode registration.Finally,the result can be shown in the system and exported for further research.