Space Target Orientation Measurement And Shape Restoration Based On Polarization 3D Imaging

In the developing space technology,space target orientation measurement technology has always been one of the key technologies,the technology can build the relative orientation relationship between the different space target and achieve the important function like the space docking control,mechanical arm,space target acquisition and surface detection space activities,so the study of space target orientation measurement technology has the great importance to the development of space technology.Based on the study of the polarization characteristics of light wave,this paper proposes a space target orientation measurement technology based on polarization 3D reconstruction,and realizes the passive non-cooperative target orientation measurement with a single camera.In addition,this paper proposes a shadow distortion correction algorithm to correct the shadow distortion in orientation measurement technology successfully.At present,in the field of orientation measurement,most technologies need to obtain a priori information such as the surface shape of the target,so these orientation measurements can only be carried out for cooperative targets.In the field of non-cooperative target orientation measurement,the current measurement technology has some problems such as complex optical system and limited imaging distance.In order to solve this problem,this paper proposes a space target orientation measurement technology based on polarization 3D reconstruction.In the technology,a single polarization camera is used to obtain the polarization characteristics of the reflected light on the target surface,and the relationship between it and the normal direction of the target surface can be constructed to obtain the 3D shape of the target surface.Combining the feature point detection technology and the ordinary least square fitting technology,the three-dimensional coordinates of the target feature points in the world coordinate system are positioned and matched to realize the attitude measurement of the space target.This method requires no target prior information and only needs a single camera to measure the orientation of non-cooperative targets.It has the advantages of no calibration and simple system.In the space scene,the shadow on the surface of the space target is caused by the blocking of sunlight by the moon,the earth or other space targets,and the lack of polarization information in the shadow part leads to the distortion of the reconstruction results,which makes it impossible to accurately measure the target orientation.To solve this problem,this paper proposes a surface distortion correction algorithm.The algorithm divides the penumbra and the umbra by analyzing the difference of the polarization characteristics of different shadow regions.In the light region and the umbra region,the polarization characteristics are well preserved,so it is not necessary to change the data,and the polarization 3D reconstruction can be conducted directly on this part.In penumbra region,the polarization characteristics of this region cannot be used because of serious distortion.Therefore,the gradient in this region is estimated by taking the mean value in the neighborhood.The obtained penumbra gradient is combined with the light and umbra gradients to realize the correction of shadow distortion in polarization 3D reconstruction.The shadow distortion correction algorithm can retain most of the polarization information in the shadow region,and has a good recovery effect on the details of the final polarization3 D reconstruction results,so as to ensure that the attitude measurement of the target can still be carried out in the presence of shadow occlusion.This thesis research results show that the space target orientation measuring and shape recovery technique based on polarization 3D reconstruction technology has good effectiveness,and the technology compared to other technique has the advantages of simple system,low cost,strong adaptability to environment and others,which makes the technology has good prospects for development.