Reconstruction for limited-projection fluorescence molecular tomography based on projected restarted conjugate gradient normal residual

Limited-projection fluorescence molecular tomography (FMT) can greatly reduce the acquisition time, which is suitable for resolving fast biology processes in vivo but suffers from severe ill-posedness because of the reconstruction using only limited projections. To overcome the severe ill-posedness, we report a reconstruction method based on the projected restarted conjugate gradient normal residual. The reconstruction results of two phantom experiments demonstrate that the proposed method is feasible for limited-projection FMT.     

Fast reconstruction in fluorescence molecular tomography using data compression of intra- and inter-projections

In order to improve the reconstruction accuracy in fluorescence molecular tomography(FMT), a common approach is to increase the number of fluorescence data or projections. However, this approach consumes too much memory space and computational time. In this Letter, a data compression strategy that involves the removal of the redundant information from both intra- and inter-projections is proposed to reduce the dimension of the FMT inverse problem. The performance of this strategy is tested with phantom and in vivo mouse experiments.The results demonstrate that the proposed data compression strategy can accelerate the FMT reconstruction nearly tenfold and almost without any quality degradation.     

Revisiting the normalized Born approximation: effects of scattering

The normalized Born approximation has been suggested as a ratiometric method in fluorescence molecular tomography (FMT) applications, to account for heterogeneity variations. The method enabled practical inversions, as it offered fluorescence reconstruction accuracy over a wide range of absorption heterogeneity, while also accounting for unknown experimental factors, such as the various system gains and losses. Yet it was noted that scattering variations affect the robustness and accuracy. Herein we decompose the effects of absorption and scattering and capitalize on the recent development of hybrid FMT/x-ray computed tomography imaging methods to proposed amendments to the method, which improve the overall accuracy of the approach.     

Tikhonov-regularization-based projecting sparsity pursuit method for fluorescence molecular tomography reconstruction

For fluorescence molecular tomography(FMT),image quality could be improved by incorporating a sparsity constraint.The L1 norm regularization method has been proven better than the L2 norm,like Tikhonov regularization.However,the Tikhonov method was found capable of achieving a similar quality at a high iteration cost by adopting a zeroing strategy.By studying the reason,a Tikhonov-regularization-based projecting sparsity pursuit method was proposed that reduces the iterations significantly and achieves good image quality.It was proved in phantom experiments through time-domain FMT that the method could obtain higher accuracy and less oversparsity and is more applicable for heterogeneous-target reconstruction,compared with several regularization methods implemented in this Letter.     

快速估计荧光分子断层成像中单个荧光物的深度

荧光分子断层成像支持在体无创研究长时间跨度的分子事件,满足21世纪系统化地观测生命过程的要求。在其复杂且耗时的重建中,先验信息有助于加快重建速度,提高重建图像的质量。文章将求解荧光物的深度作为待优化问题,由单幅荧光图像直接快速地估计深度信息。首先根据生物组织内的扩散模型和外推边界条件,推导出生物体边界上两点处荧光强度的比值R_f。然后用粒子群优化算法,在吸收系数和散射系数的估计区间内,由最小化生物体边界上两点处模型值RM_f与测量值RT_f之间的差,估计出荧光物的深度。不同尺寸荧光物的两个仿体实验的结果表明,所提出的方法不需要网格剖分和重建,能快速简单地估计出单个类似于球体的荧光物的深度。     

时域荧光分子层析图像重建的线性特征数据法

通过扩展用于时域扩散光成像(Diffuse Optical Tomography, DOT)的广义脉冲谱技术,提出了一种用于时域荧光分子层析成像(Fluorescence Molecular Tomography, FMT)的线性特征数据图像重建算法.此算法能够同时重建荧光产率和荧光寿命,并且利用模拟数据对此方法进行验证,证明了算法的有效性.     

Using Laser Measuring and SFM Algorithm for Fast 3D Reconstruction of Objects

Effective measurement of the reflective or transparent surface of an object has always been a disadvantage in laser scanning modeling. We propose a fast and complete three-dimensional (3D) reconstruction method for small static objects using laser scanning and the structure from motion (SFM) algorithm. Meanwhile, a complete reconstruction workflow is designed and a multi-angle 3d reconstruction system is set up. To generate the complete point cloud model of the object, the SFM algorithm is used to reconstruct the surface part of the object, the data for which cannot be obtained by the laser measuring instrument. The experimental results show that this method not only improves the speed, accuracy, integrity, and visual effect of 3D reconstruction of small objects, but also extends the scope of 3D reconstruction of laser measurement.     

基于三维激光扫描的物体重构建模

针对锂离子电池SOC(荷电状态)难以估算的问题,通过对电池建立等效的Thevenin电路模型,对不同时刻的SOC的模型参数进行拟合得到动态的模型参数,在Matlab中借助Simulink建立仿真模型,采用模块化结构,建立基于卡尔曼滤波算法的电池SOC估算系统;利用测得的电池电压电流,仿真系统可直接估算出实时的电池SOC,与实际的电池SOC对比,误差保持在2.5%以内,表明该方法可以有效的估计电池的SOC,对于锂离子电池在实际应用的容量估算有着重要意义。     

Three-dimensional integral imaging with improved visualization using subpixel optical ray sensing

In this Letter, we propose an improved three-dimensional (3D) image reconstruction method for integral imaging. We use subpixel sensing of the optical rays of the 3D scene projected onto the image sensor. When reconstructing the 3D image, we use a calculated minimum subpixel distance for each sensor pixel instead of the average pixel value of integrated pixels from elemental images. The minimum subpixel distance is defined by measuring the distance between the center of the sensor pixel and the physical position of the imaging lens point spread function onto the sensor, which is projected from each reconstruction point for all elemental images. To show the usefulness of the proposed method, preliminary 3D imaging experiments are presented. Experimental results reveal that the proposed method may improve 3D imaging visualization because of the superior sensing and reconstruction of optical ray direction and intensity information for 3D objects.     

Computer-generated kinoforms of real-existing full-color 3D objects using pure-phase look-up-table method

A computational method based on pure-phase look-up-table (LUT) is proposed for generating kinoforms of full-color real-existing three-dimensional (3D) objects. The principle of the pure-phase LUT method is described. 3D depth as well as color information of a full-color 3D object is obtained by the full-color 3D profile measurement approach based on binocular vision. The obtained full-color 3D data is decomposed into red (R), green (G), and blue (B) channels, and kinoforms of each channel are calculated from the depth map and color information of the corresponding channel using the pure-phase LUT method. In order to reduce the speckle noise of reconstructed full-color 3D image, sequential kinoforms of each color channel are generated by adding dynamic-pseudorandom phase factor into the object domain. Numerical reconstruction and optical reconstruction with a phase-only spatial light modulator (SLM) show that, with the proposed method, full-color holographic 3D display of real-existing full-color 3D objects is available.     

于散乱三维点云的缺陷检测和三维重构方法

设备表面的缺陷检测对于保证安全生产避免经济损失具有重要意义。针对基于设备表面散乱三维点云缺陷检测和三维重构算法复杂的问题,提出了一种基于散乱三维点云的缺陷检测和三维重构方法。对散乱三维点云沿某一轴向进行分层处理,将同一层内的三维点进行移位规则化处理,并对规则化的三维点云进行缺陷检测和三维重构。分别对无缺陷设备表面和凹凸缺陷设备表面进行缺陷检测和三维重构,规则化前后三维数据缺陷计算结果相对误差为1.01%。实验结果表明,将散乱三维点云分层和规则化处理有效降低了缺陷检测和三维重构的复杂度,易于实现。     

3D shape reconstruction of parabolic trough collector from gradient data based on slope stitching approach

A method based on slope stitching for measurement of a large off-axis parabolic trough collector is proposed and applied to the surface shape reconstructed from the gradient data acquired by using the reverse Hartmann test.The entire reflector is divided into three sections with overlapping zones along the concentration direction.A mathematical model for the slope stitching algorithm is developed.An improved reconstruction method combining Zernike slope polynomials iterative fitting with the Southwell integration algorithm is utilized to recover the real three-dimensional(3 D) shape of the collector.The efficiency and validity of the improved reconstruction method and the stitching algorithm are experimentally verified.     

Fringe shaping for high-/low-reflectance surface in single-trial phase-shifting profilometry

This study describes a novel fringe-shaping technique developed to alleviate the fringe truncation problem engendered by the acquired saturated and/or weak fringe images from high-/low-reflectance surfaces of three-dimensional(3D) objects in phase-shifting profilometry. The particle swarm optimization algorithm is employed to perform the recovery of the truncated fringes with optimal fitting for compensation after single-trial acquisition. The results show that the proposed method improves phase recovery accuracy to accomplish 3 D surface reconstruction with only one set of phase-shifting fringes under different truncation sceneries.     

复杂轮廓表面激光检测及三维重构技术的研究

基于零件实物样件的几何模型反求技术已成为CAD/CAM领域中的研究热点之一。以航空航天用MJ螺纹为对象 ,对逆向工程中的两大关键技术———表面数字化及三维重构技术进行了分析和研究。提出了用一种新型激光光纤传感器实现复杂轮廓表面的非接触数字化检测方法 ,描述了测量原理。通过二维截面轮廓图重构三维面型 ,初步的实验结果验证了此方法的有效性和实用性     

Inclined focusing method in subsurface radar

An oblique scanning method for subsurface radio tomography is proposed that is aimed at reconstructing the inhomogeneity 3D distribution and discovering out-of-level scatterers under a planar interface. The method is based on synthetic-aperture radar technology and uses data of multiposition sensing by omnidi-rectional antennas elevated over the Earth’s surface. The focusing of the synthetic-aperture radar is based on fast Fourier transformation providing a fast algorithm of 3D reconstruction. The method is verified numerically and in real experiments.     

基于单幅图像大尺寸实际平面上的光点定位方法

 为满足某地面实验中视觉测量系统的研制需求,研究了一种基于单幅图像的大尺寸实际平面上光点的定位方法。通过建立关于实际平面上光点3D坐标的数学模型,结合利用图像确定的通过光点的空间光束,实现了由单幅图像确定光点的3D坐标。依据具体特点,把实际平面分为高阶曲面型、分块平面型和分块曲面型3种类型,并分别给出了相应类型的光点定位方法。仿真实验验证了所提出方法的正确性,并比较分析了方法的精确性;实际试验数据表明,所提出方法可以满足尺寸为8000mm×8000mm的大型实际平面上光点的定位需求,定位误差小于1mm。     

Growth model for atomic ordering: the case for quadruple-period ordering in GaAsSb alloys

Quadruple-period ordering in GaAsSb alloys is studied both theoretically and experimentally. A growth model is proposed to account for the observed three-dimensional (3D) ordered structure. The model is qualitatively different from the widely accepted surface reconstruction and dimerization-induced ordering models that strictly speaking explain only the in-plane 2D patterns. Here, we show that the already ordered substrate will affect the reconstruction of the growth front with respect to the substrate to ensure a correct stacking of the individual 2D ordered layers into the observed 3D lattice.     

三维光学数字像的一种解析逼近模型

利用双三次均匀Ｂ样条曲面片建立三维光学数字图像的逼近模型。该数学模型是依据双三次均匀Ｂ样条曲面片对三维光学数字图像的分片逼近技术来建立的。言语中给出了空间自由表面的双三次均匀Ｂ样条表达方法和三维数字像的Ｂ样条重构结果。     

Three-dimensional recognition of occluded objects by using computational integral imaging

We have proposed a method to recognize partially occluded three-dimensional (3D) objects by using 3D volumetric reconstruction integral imaging (II). An II system captures multiple perspectives of occluded objects by using a microlens array. The reconstruction of the occluded 3D scene and target recognition are done digitally to reduce the effects of the occlusion. To verify system performance, we have implemented an optimum filter for object recognition. Both two-dimensional (2D) images and 3D II volumetric reconstructed images are considered. The correlation results of occluded 3D images for volumetric reconstruction show substantial improvements compared with those for conventional 2D imaging of occluded images.     

双探头三维表面轮廓测量系统

提出了一种将原子力显微(AFM)探头与位置敏感探测器测距探头相结合的双探头三维表面轮廓测量新方法, 可在获取样品表面轮廓的同时, 测定样品局部形貌。搭建了双探头三维表面轮廓测量系统, 阐述了系统的工作原理, 并对其结构组成包括双探头、步进扫描台和计算机控制平台进行了说明。用2000 line/mm的光栅进行了扫描实验, 对系统的测量范围进行了标定。以外径8 mm、内径4 mm的金属垫圈为样品, 进行了整体三维表面轮廓与局部表面形貌测量实验, 给出了垫圈表面图和局部三维形貌图。结果表明, 该系统能满足不同尺寸和材质的样品的测量要求, 即可实现对样品轮廓的大范围扫描测量, 又可对样品局部进行高精度形貌测量。