Design And Implementation Of The Positioning Method Of Spatial Forward Intersection Based On Android Mobile Phone

In recent years,Android smart phone market share increased year by year,and Android phone linked with people's daily life more and more closely.With the popularity of Android mobile positioning function,positioning diversity and mobile network technology maturing and the rising of 4G and 4G+ network technology,the mobile phone software which using Android mobile phone location services continue to appear.So how to obtain the location information efficiently,intelligently and diversified has become an important issue in the current smart phone location services.The positioning of the existing Android mobile location service software(such as Baidu map,Auto Navi map,etc.)are mainly based on the mobile positioning sensor technology(such as GPS,GLONASS)and wireless communication network for Telecom mobile operators(such as GSM,CDMA,etc.).When the user needs to obtain location information,he will get the location of the phone.Sometimes because of the location,transportation,natural disasters in life,users need to get the target location information at a certain distance from the target point,so that the traditional mobile phone location model will not meet the needs of users.So in this paper,combine mobile phone positioning with photogrammetry stereo images spatial forward intersection method,use the camera function,image information and sensor components of mobile phone to realize real-time acquisition of location information for target points in the case of no control points and no contact.The test equipment used in this paper is Lenovo ZUK Z2 mobile phone with Android 6.0 system.Use the camera function,the positioning chip,the sensor element of the mobile phone to obtain the target point photos and the external orientation elements of the mobile phone photos,do data processing and precision analysis of the obtained information and make an objective evaluation of positioning accuracy.The main research of this paper is as follows:(1)Research and develop the Android mobile phone camera function.Use Android Camera API to develop the mobile phone camera through the demand analysis of experiment to realize camera interface design,preview method,auto focus,resolution settings,photo storage and browsing capabilities in order to provide the basis for the stereo images spatial forward intersection method and get high resolution photos.(2)Get the exterior orientation elements of the photo and use the positioning function of Android mobile phone to get the location information of the mobile phone camera as the exterior orientation line elements of the photo,At the same time to return the direction sensor for mobile phone camera,the magnetic field sensor,the direction sensor and other parameters at the same time,get the elements of exterior orientation of mobile phone through calculation.(3)Get the image space coordinate of image point,the pixel coordinates of image points are measured in the pixel coordinate system,convert pixel coordinates to image plane coordinates(x,y)through coordinate transformation.Mobile phone camera is usually fixed focal length due to size limitations,image space coordinates(x,y,-f)can be obtained when the main point is located in the photo center.(4)Solute object space coordinates of the same image point based on photogrammetry stereo images spatial forward intersection method.Use spatial forward intersection method of point projection coefficient when solute.(5)Get multi group coordinate data through the acquisition of the same target points of the group of stereo pairs.Do data processing of the coordinates of the target points,calculate accuracy and stability of azimuth element of exterior orientation and line element of exterior orientation.Combining with the measurement of plane coordinates,lens distortion does positioning accuracy anal ysis of the effect of accuracy based on Android mobile phone spatial forward intersection.