In order to achieve a high precision in three-dimensional（3D） multi-camera measurement system, an efficient multi-cameracalibration method is proposed. A stitching method of large scalecalibration targets is deduced...In order to achieve a high precision in three-dimensional（3D） multi-camera measurement system, an efficient multi-cameracalibration method is proposed. A stitching method of large scalecalibration targets is deduced, and a fundamental of multi-cameracalibration based on the large scale calibration target is provided.To avoid the shortcomings of the method, the vector differencesof reprojection error with the presence of the constraint conditionof the constant rigid body transformation is modelled, and mini-mized by the Levenberg-Marquardt （LM） method. Results of thesimulation and observation data calibration experiment show thatthe accuracy of the system calibrated by the proposed methodreaches 2 mm when measuring distance section of 20 000 mmand scale section of 7 000 mm × 7 000 mm. Consequently, theproposed method of multi-camera calibration performs better thanthe fundamental in stability. This technique offers a more uniformerror distribution for measuring large scale space.展开更多
针对大视场红外相机在轨调焦时受大气条件、地物丰富度、月相角等因素影响导致对地调焦和对月调焦周期长、效率低的问题,文章提出一种基于星点亚像元误差补偿的红外相机在轨检焦方法,通过对未经大气退化的星点图像进行精准质心定位提取...针对大视场红外相机在轨调焦时受大气条件、地物丰富度、月相角等因素影响导致对地调焦和对月调焦周期长、效率低的问题,文章提出一种基于星点亚像元误差补偿的红外相机在轨检焦方法,通过对未经大气退化的星点图像进行精准质心定位提取清晰度评价指标,有效规避外界因素的影响,提升在轨检焦效率,保障在轨检焦精度。首先对星点图像分别采用自适应阈值质心法和高斯拟合法提取质心估计值;依据图像信噪比、星点目标能量集中度确定最佳因子,构建误差补偿模型进行精确质心定位;再提取图像点扩散函数的波形半高宽(Full Width at Half Maximum,FWHM)作为在轨检焦清晰度评价指标;设置不同谱段、不同能量集中度的星点红外图像作为在轨检焦图像,分别采用质心法、高斯拟合法及星点亚像元误差补偿方法进行目标质心提取并估计FWHM,实验结果表明:三种方法的质心提取平均误差分别为0.1195、0.0107、0.0027,均方根误差分别为0.1210、0.0124、0.0085,星点亚像元误差补偿方法质心提取误差最小,稳定性最好。能量集中度为0.4~0.8之间时,采用星点亚像元误差补偿方法质心提取平均误差均小于0.01,优于其他方法。在此基础上,采用该方法提取的FWHM平均精度提升了三倍以上,且不受星点质心位置随机性的影响,对于实现基于恒星的在轨检焦具有较高的可靠性和稳定性,满足在轨检焦要求。展开更多
ToF(Time of Flight)深度相机是获取三维点云数据的重要手段之一,但ToF深度相机受到自身硬件和外部环境的限制,其测量数据存在一定的误差。本文针对ToF深度相机的非系统误差进行研究,通过实验验证了被测目标的颜色、距离和相对运动等因...ToF(Time of Flight)深度相机是获取三维点云数据的重要手段之一,但ToF深度相机受到自身硬件和外部环境的限制,其测量数据存在一定的误差。本文针对ToF深度相机的非系统误差进行研究,通过实验验证了被测目标的颜色、距离和相对运动等因素均会对深度相机获取的数据产生影响,且影响均不相同。本文提出了一种新的测量误差模型对颜色和距离产生的误差进行校正,对于相对运动产生的误差,建立了三维运动模糊函数进行恢复,通过对所建立的校正模型进行数值分析,距离和颜色的残余误差小于4 mm,相对运动所带来的误差小于0.7 mm。本文所做工作改善了ToF深度相机的测量数据的质量,为开展三维点云重建等工作提供了更精准的数据支持。展开更多
A lower bound to errors of measuring object position is constructed as a function of parameters of a monocular computer vision system (CVS) as well as of observation conditions and a shape of an observed marker. This ...A lower bound to errors of measuring object position is constructed as a function of parameters of a monocular computer vision system (CVS) as well as of observation conditions and a shape of an observed marker. This bound justifies the specification of the CVS parameters and allows us to formulate constraints for an object trajectory based on required measurement accuracy. For making the measurement, the boundaries of marker image are used.展开更多
基金supported by the National Natural Science Foundation of China(61473100)
文摘In order to achieve a high precision in three-dimensional（3D） multi-camera measurement system, an efficient multi-cameracalibration method is proposed. A stitching method of large scalecalibration targets is deduced, and a fundamental of multi-cameracalibration based on the large scale calibration target is provided.To avoid the shortcomings of the method, the vector differencesof reprojection error with the presence of the constraint conditionof the constant rigid body transformation is modelled, and mini-mized by the Levenberg-Marquardt （LM） method. Results of thesimulation and observation data calibration experiment show thatthe accuracy of the system calibrated by the proposed methodreaches 2 mm when measuring distance section of 20 000 mmand scale section of 7 000 mm × 7 000 mm. Consequently, theproposed method of multi-camera calibration performs better thanthe fundamental in stability. This technique offers a more uniformerror distribution for measuring large scale space.
文摘针对大视场红外相机在轨调焦时受大气条件、地物丰富度、月相角等因素影响导致对地调焦和对月调焦周期长、效率低的问题,文章提出一种基于星点亚像元误差补偿的红外相机在轨检焦方法,通过对未经大气退化的星点图像进行精准质心定位提取清晰度评价指标,有效规避外界因素的影响,提升在轨检焦效率,保障在轨检焦精度。首先对星点图像分别采用自适应阈值质心法和高斯拟合法提取质心估计值;依据图像信噪比、星点目标能量集中度确定最佳因子,构建误差补偿模型进行精确质心定位;再提取图像点扩散函数的波形半高宽(Full Width at Half Maximum,FWHM)作为在轨检焦清晰度评价指标;设置不同谱段、不同能量集中度的星点红外图像作为在轨检焦图像,分别采用质心法、高斯拟合法及星点亚像元误差补偿方法进行目标质心提取并估计FWHM,实验结果表明:三种方法的质心提取平均误差分别为0.1195、0.0107、0.0027,均方根误差分别为0.1210、0.0124、0.0085,星点亚像元误差补偿方法质心提取误差最小,稳定性最好。能量集中度为0.4~0.8之间时,采用星点亚像元误差补偿方法质心提取平均误差均小于0.01,优于其他方法。在此基础上,采用该方法提取的FWHM平均精度提升了三倍以上,且不受星点质心位置随机性的影响,对于实现基于恒星的在轨检焦具有较高的可靠性和稳定性,满足在轨检焦要求。
文摘ToF(Time of Flight)深度相机是获取三维点云数据的重要手段之一,但ToF深度相机受到自身硬件和外部环境的限制,其测量数据存在一定的误差。本文针对ToF深度相机的非系统误差进行研究,通过实验验证了被测目标的颜色、距离和相对运动等因素均会对深度相机获取的数据产生影响,且影响均不相同。本文提出了一种新的测量误差模型对颜色和距离产生的误差进行校正,对于相对运动产生的误差,建立了三维运动模糊函数进行恢复,通过对所建立的校正模型进行数值分析,距离和颜色的残余误差小于4 mm,相对运动所带来的误差小于0.7 mm。本文所做工作改善了ToF深度相机的测量数据的质量,为开展三维点云重建等工作提供了更精准的数据支持。
文摘A lower bound to errors of measuring object position is constructed as a function of parameters of a monocular computer vision system (CVS) as well as of observation conditions and a shape of an observed marker. This bound justifies the specification of the CVS parameters and allows us to formulate constraints for an object trajectory based on required measurement accuracy. For making the measurement, the boundaries of marker image are used.
