This paper describes a multiple camera-based method to reconstruct the 3D shape of a human foot. From a foot database, an initial 3D model of the foot represented by a cloud of points is built. The shape parameters, w...This paper describes a multiple camera-based method to reconstruct the 3D shape of a human foot. From a foot database, an initial 3D model of the foot represented by a cloud of points is built. The shape parameters, which can characterize more than 92% of a foot, are defined by using the principal component analysis method. Then, using ＂active shape models＂, the initial 3D model is adapted to the real foot captured in multiple images by applying some constraints （edge points＇ distance and color variance）. We insist here on the experiment part where we demonstrate the efficiency of the proposed method on a plastic foot model, and also on real human feet with various shapes. We propose and compare different ways of texturing the foot which is needed for reconstruction. We present an experiment performed on the plastic foot model and on human feet and propose two different ways to improve the final 3D shapers accuracy according to the previous experiments＇ results. The first improvement proposed is the densification of the cloud of points used to represent the initial model and the foot database. The second improvement concerns the projected patterns used to texture the foot. We conclude by showing the obtained results for a human foot with the average computed shape error being only 1.06 mm.展开更多
钻井过程中掉块的监测与识别对于及时发现和减缓井壁不稳定和卡钻等井下复杂至关重要。当前,掉块监测主要依赖人工监测,但该方法易受主观影响且耗时较长,存在滞后性。为此,提出一种基于3D视觉的钻井掉块自动识别与特征判断方法。该方法...钻井过程中掉块的监测与识别对于及时发现和减缓井壁不稳定和卡钻等井下复杂至关重要。当前,掉块监测主要依赖人工监测,但该方法易受主观影响且耗时较长,存在滞后性。为此,提出一种基于3D视觉的钻井掉块自动识别与特征判断方法。该方法利用3D成像技术来获取振动筛上返出掉块的三维深度信息,以构建掉块图像样本库,并以You Only Look Once v8s(YOLOv8s)为基础目标检测模型,结合引入的卷积块注意力模块(CBAM),建立了CBAM-YOLOv8s掉块目标检测模型。通过将3D相机实时获取的三维深度信息集成到模型中,不仅实现了对掉块的实时监测和准确识别,还能够在识别的基础上判断其形状特征,从而实现井壁失稳性分析和井眼状况的实时评估。实验结果表明:CBAM模块的引入增强了模型对掉块关键特征的关注;集成实时获取三维深度信息的CBAM-YOLOv8s模型对掉块识别精确率和召回率分别达到96.01%和93.40%;扩展模型在掉块形状特征预测中的误差均小于10%。结论认为,基于3D视觉技术的实时掉块可视化监测方法具有良好的可行性和有效性,能够准确识别出掉块及其形状特征,这一方法将为井壁稳定性早期预警和井下复杂提供支持。展开更多
Instead of traditionally using a 3D physical model with many control points on it, a calibration plate with printed chess grid and movable along its normal direction is implemented to provide large area 3D control poi...Instead of traditionally using a 3D physical model with many control points on it, a calibration plate with printed chess grid and movable along its normal direction is implemented to provide large area 3D control points with variable Z values. Experiments show that the approach presented is effective for reconstructing 3D color objects in computer vision system.展开更多
In this paper, we present a new technique of 3D face reconstruction from a sequence of images taken with cameras having varying parameters without the need to grid. This method is based on the estimation of the projec...In this paper, we present a new technique of 3D face reconstruction from a sequence of images taken with cameras having varying parameters without the need to grid. This method is based on the estimation of the projection matrices of the cameras from a symmetry property which characterizes the face, these projections matrices are used with points matching in each pair of images to determine the 3D points cloud, subsequently, 3D mesh of the face is constructed with 3D Crust algorithm. Lastly, the 2D image is projected on the 3D model to generate the texture mapping. The strong point of the proposed approach is to minimize the constraints of the calibration system： we calibrated the cameras from a symmetry property which characterizes the face, this property gives us the opportunity to know some points of 3D face in a specific well-chosen global reference, to formulate a system of linear and nonlinear equations according to these 3D points, their projection in the image plan and the elements of the projections matrix. Then to solve these equations, we use a genetic algorithm which consists of finding the global optimum without the need of the initial estimation and allows to avoid the local minima of the formulated cost function. Our study is conducted on real data to demonstrate the validity and the performance of the proposed approach in terms of robustness, simplicity, stability and convergence.展开更多
针对航天器相对导航问题,以空间站表面为"特殊地形",提出一种基于大型航天器表面巡检的相对导航算法。首先,运用巡检飞行器上的TOF(Time of Flight)相机测量空间站表面局部点云数据,以该点云数据为实时图,以空间站表面先验点...针对航天器相对导航问题,以空间站表面为"特殊地形",提出一种基于大型航天器表面巡检的相对导航算法。首先,运用巡检飞行器上的TOF(Time of Flight)相机测量空间站表面局部点云数据,以该点云数据为实时图,以空间站表面先验点云数据为基准图。然后,利用3D-Zernike矩与三维地形间的一一对应关系,将三维地形匹配转化为基于3D Zernike矩的特征向量匹配。在此基础上求解实时图与匹配上的基准图间的相对位置、相对姿态,从而确定两航天器间的相对导航参数,并通过实验分析了匹配精度及速度的主要影响因素。最后,将该相对导航参数与惯性系统推算的相对导航参数在扩展卡尔曼滤波器的框架下实现信息融合,估计了巡检飞行器与空间站间的相对位置、相对姿态,实验结果表明,相对位置精度优于0.002m,相对姿态精度优于0.1°。展开更多
基金This work was supported by Grant-in-Aid for Scientific Research (C) (No.17500119)
文摘This paper describes a multiple camera-based method to reconstruct the 3D shape of a human foot. From a foot database, an initial 3D model of the foot represented by a cloud of points is built. The shape parameters, which can characterize more than 92% of a foot, are defined by using the principal component analysis method. Then, using ＂active shape models＂, the initial 3D model is adapted to the real foot captured in multiple images by applying some constraints （edge points＇ distance and color variance）. We insist here on the experiment part where we demonstrate the efficiency of the proposed method on a plastic foot model, and also on real human feet with various shapes. We propose and compare different ways of texturing the foot which is needed for reconstruction. We present an experiment performed on the plastic foot model and on human feet and propose two different ways to improve the final 3D shapers accuracy according to the previous experiments＇ results. The first improvement proposed is the densification of the cloud of points used to represent the initial model and the foot database. The second improvement concerns the projected patterns used to texture the foot. We conclude by showing the obtained results for a human foot with the average computed shape error being only 1.06 mm.
文摘钻井过程中掉块的监测与识别对于及时发现和减缓井壁不稳定和卡钻等井下复杂至关重要。当前,掉块监测主要依赖人工监测,但该方法易受主观影响且耗时较长,存在滞后性。为此,提出一种基于3D视觉的钻井掉块自动识别与特征判断方法。该方法利用3D成像技术来获取振动筛上返出掉块的三维深度信息,以构建掉块图像样本库,并以You Only Look Once v8s(YOLOv8s)为基础目标检测模型,结合引入的卷积块注意力模块(CBAM),建立了CBAM-YOLOv8s掉块目标检测模型。通过将3D相机实时获取的三维深度信息集成到模型中,不仅实现了对掉块的实时监测和准确识别,还能够在识别的基础上判断其形状特征,从而实现井壁失稳性分析和井眼状况的实时评估。实验结果表明:CBAM模块的引入增强了模型对掉块关键特征的关注;集成实时获取三维深度信息的CBAM-YOLOv8s模型对掉块识别精确率和召回率分别达到96.01%和93.40%;扩展模型在掉块形状特征预测中的误差均小于10%。结论认为,基于3D视觉技术的实时掉块可视化监测方法具有良好的可行性和有效性,能够准确识别出掉块及其形状特征,这一方法将为井壁稳定性早期预警和井下复杂提供支持。
基金Supported by the Natural Science Foundation of China (69775022)the State High-Technology Development program of China(863 306ZT04 06 3)
文摘Instead of traditionally using a 3D physical model with many control points on it, a calibration plate with printed chess grid and movable along its normal direction is implemented to provide large area 3D control points with variable Z values. Experiments show that the approach presented is effective for reconstructing 3D color objects in computer vision system.
文摘In this paper, we present a new technique of 3D face reconstruction from a sequence of images taken with cameras having varying parameters without the need to grid. This method is based on the estimation of the projection matrices of the cameras from a symmetry property which characterizes the face, these projections matrices are used with points matching in each pair of images to determine the 3D points cloud, subsequently, 3D mesh of the face is constructed with 3D Crust algorithm. Lastly, the 2D image is projected on the 3D model to generate the texture mapping. The strong point of the proposed approach is to minimize the constraints of the calibration system： we calibrated the cameras from a symmetry property which characterizes the face, this property gives us the opportunity to know some points of 3D face in a specific well-chosen global reference, to formulate a system of linear and nonlinear equations according to these 3D points, their projection in the image plan and the elements of the projections matrix. Then to solve these equations, we use a genetic algorithm which consists of finding the global optimum without the need of the initial estimation and allows to avoid the local minima of the formulated cost function. Our study is conducted on real data to demonstrate the validity and the performance of the proposed approach in terms of robustness, simplicity, stability and convergence.
文摘针对航天器相对导航问题,以空间站表面为"特殊地形",提出一种基于大型航天器表面巡检的相对导航算法。首先,运用巡检飞行器上的TOF(Time of Flight)相机测量空间站表面局部点云数据,以该点云数据为实时图,以空间站表面先验点云数据为基准图。然后,利用3D-Zernike矩与三维地形间的一一对应关系,将三维地形匹配转化为基于3D Zernike矩的特征向量匹配。在此基础上求解实时图与匹配上的基准图间的相对位置、相对姿态,从而确定两航天器间的相对导航参数,并通过实验分析了匹配精度及速度的主要影响因素。最后,将该相对导航参数与惯性系统推算的相对导航参数在扩展卡尔曼滤波器的框架下实现信息融合,估计了巡检飞行器与空间站间的相对位置、相对姿态,实验结果表明,相对位置精度优于0.002m,相对姿态精度优于0.1°。
