Research On Panoramic Image Generation Technology For 3D Reconstruction

Panoramic image is a kind of efficient expression method for 3D scene visualization.Regardless of the common camera or panoramic camera can only collect the local scene,we need a panoramic image mosaic technology to solve the limitations of the perspective of these imaging device and to obtain a panorama of wide view and high resolution.The electronic theodolite is a kind of high-precision angle measuring instrument and it has a lot of advantages,such as high accuracy,easy operation and non-contact measurement and it can realize automatic reading.A digital camera can be fixed on the telescope of the electronic theodolite to form a theodolite-camera.This system can achieve fast and accurate image sequence stitching,and make the mosaic not be affected by the overlapping regions of sequences.Panorama can create a virtual 3D space,but it is not measurable, so it needs 3D reconstruction.Panoramic 3D reconstruction is a 3D scene reconstruction method using panorama sequence,which is an important content of 3D reconstruction theory.It can effectively simplify the complexity and improve its efficiency due to the scene to be reconstructed can be covered by relatively small number of panoramic images.In this paper,some relevant theories and methods of image stitching and panoramic 3D reconstruction were deeply researched.Panoramic images were generated using the image data known azimuth angle,then the panoramic sparse point cloud reconstruction was accomplished using panoramic image sequence.Firstly,the system calibration based on the space resection method of the theodolite-camera was completed, including the theodolite calibration and the camera calibration at the initial position. The fixed position and orientation between the camera and the telescope was calibrate,then the exterior orientation elements of the image sequence were calculated by the angle measuring function of the theodolite.Secondly, according to the characteristics of the image sequence captured by the theodolite-camera, the spherical model was used to describe the projection relationship of the panoramic image.Then,the method of building spherical cameramodel from a theodolite-camera system and the representing and storing of the spherical panorama and the method of browsing the interested region were discussed.Finally,the two-view geometry under spherical camera model was deduced.Meanwhile,some concepts,such as the space forward intersection of the spherical model, relative orientation of the camera and determination of the epipolar line were discussed.Furthermore,this paper introduced the estimation of spherical epipolar error and spherical re-projection error.The sparse point cloud reconstruction of 3D scene was realized by using the two-view geometry algorithm.