- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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A flexible 3D point reconstruction with homologous laser point array and monocular vision
摘要： A 3D recovery approach is achieved by the monocular vision sensor and the homologous laser point array with the arbitrary relative pose to the 2D reference. In the modeling process, firstly, the 3D texture board is moved to different positions in the view field of the vision sensor. Therefore, the laser rays intersect with the cubic board and generate laser points on it. Then, the Plücker matrices of the laser rays are determined by the laser points. The algebraic solution of the joint point of laser rays, the optic center of the projector, is contributed by the singular value decomposition. Thirdly, the laser rays are refined by the algebraic solution of the joint point and represented in the 2D-reference coordinate frame. Finally, the reconstruction is achieved by the calibrated laser rays of the projector. The reconstruction method is experimentally conducted to verify the performance and precision in various measurement conditions. The reconstruction error averages are 0.942 mm, 1.055 mm, 1.374 mm, 2.063 mm, under the 700 mm–1000 mm measuring distances between the vision sensor and the optic center. As there is no strict requirement for the relative installation position and orientation between the laser-ray projector and the 2D reference, the approach prompts the flexibility for the on-site active-vision measurement.
关键词： Structured light,Optical inspection,Laser rays,Reconstruction
更新于2025-09-23 15:19:57
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Tomographic reconstruction algorithms for structured gas density profiles of the targets for laser wakefield acceleration
摘要： The output of a laser wakefield accelerator strongly depends on the gas target density profile. In this work we focus on the reconstruction of the 3D density profiles from tomographic measurements. We compare analytical and iterative methods, and we propose a new one, FARM, which is tailored for the reconstruction of gas targets for laser wakefield acceleration. Several methods are tested on both simplified and realistic geometries. The algorithms are evaluated in terms of the quality of the density profile reconstruction, the number of projections needed, and the computation time required.
关键词： interferometry,tomography,laser wakefield acceleration,density profile,gas target,laser plasma acceleration,tomographic reconstruction,laser electron acceleration
更新于2025-09-23 15:19:57
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[IEEE TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - Kochi, India (2019.10.17-2019.10.20)] TENCON 2019 - 2019 IEEE Region 10 Conference (TENCON) - Use of Novel Hybrid Plasmonic Nanoparticle Complexes to Increase the Efficiency of Thin-film Solar Cells
摘要： To utilize the synergy between computed tomography (CT) and magnetic resonance imaging (MRI) data sets from an object at the same time, an edge-guided dual-modality image reconstruction approach is proposed. The key is to establish a knowledge-based connection between these two data sets for the tight fusion of different imaging modalities. Our scheme consists of four inter-related elements: 1) segmentation; 2) initial guess generation; 3) CT image reconstruction; and 4) MRI image reconstruction. Our experiments show that, aided by the image obtained from one imaging modality, even with highly under-sampled data, we can better reconstruct the image of the other modality. This approach can be potentially useful for a simultaneous CT-MRI system.
关键词： l1-norm minimization,image reconstruction,CT-MRI system,multi-modality imaging
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE SENSORS - Montreal, QC, Canada (2019.10.27-2019.10.30)] 2019 IEEE SENSORS - Passive Proximity Detection Based on a Miniaturized Pyramidal Optical Sensor
摘要： Signal processing on graph is attracting more and more attentions. For a graph signal in the low-frequency subspace, the missing data associated with unsampled vertices can be reconstructed through the sampled data by exploiting the smoothness of the graph signal. In this paper, the concept of local set is introduced and two local-set-based iterative methods are proposed to reconstruct bandlimited graph signal from sampled data. In each iteration, one of the proposed methods reweights the sampled residuals for different vertices, while the other propagates the sampled residuals in their respective local sets. These algorithms are built on frame theory and the concept of local sets, based on which several frames and contraction operators are proposed. We then prove that the reconstruction methods converge to the original signal under certain conditions and demonstrate the new methods lead to a significantly faster convergence compared with the baseline method. Furthermore, the correspondence between graph signal sampling and time-domain irregular sampling is analyzed comprehensively, which may be helpful to future works on graph signals. Computer simulations are conducted. The experimental results demonstrate the effectiveness of the reconstruction methods in various sampling geometries, imprecise priori knowledge of cutoff frequency, and noisy scenarios.
关键词： graph signal sampling and reconstruction,irregular domain,bandlimited subspace,local set,frame theory,Graph signal processing
更新于2025-09-23 15:19:57
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The detection effect of pavement 3D texture morphology using improved binocular reconstruction algorithm with laser line constraint
摘要： To improve the precision of traditional binocular reconstruction technology and better serve the traffic safety, laser line constraint was firstly introduced. Then three different matching modes, namely the default color, enhanced target line and region segmentation, were established. Finally, the improved binocular reconstruction test system and the three-dimensional texture morphology measurement accuracy evaluation device were produced. The effect of matching modes on the test precision of three-dimensional texture morphology of asphalt pavement was further analyzed. The results show that the introduction of laser line constraint improves the precision for both overall measurement and single point measurement. The improved algorithm under the region segmentation matching mode has a good reconstruction effect. The average deviation of the overall measurement is 0.02mm, and the maximum deviation of the single point measurement is 0.14mm, which can meet the requirements of pavement texture detection in skid resistance evaluation.
关键词： three-dimensional texture morphology,binocular reconstruction,region segmentation matching,laser line constraint
更新于2025-09-23 15:19:57
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Accurate modeling of event-by-event backprojection for a germanium semiconductor Compton camera for system response evaluation in the LM-ML-EM image reconstruction method
摘要： We develop an image reconstruction method, considering the physical phenomenon in the measurement process of a Compton camera. The image quality is improved by applying an accurate error model of the Compton scattering angle. The angular error has two properties: an error distribution function specific to the detector material and the variation of its function parameters, depending on each measurement event. We incorporate these factors into the backprojection of the list-mode maximum-likelihood expectation-maximization method as the system response function. We apply our image reconstruction method to simulated data assumed to be measured by a Ge-semiconductor Compton camera GREI, and the imaging data of a tumor-bearing live mouse obtained using GREI. This method is evaluated by comparing an image with variable angular error with that having fixed angular error. The consideration of the variable angle estimation error improves the spatial resolution and reduces image roughness.
关键词： Ge-semiconductor,image reconstruction,Compton camera,LM-ML-EM method,Doppler broadening
更新于2025-09-23 15:19:57
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Reconstructing 3D Face Models by Incremental Aggregation and Refinement of Depth Frames
摘要： Face recognition from two-dimensional (2D) still images and videos is quite successful even with “in the wild” conditions. Instead, less consolidated results are available for the cases in which face data come from non-conventional cameras, such as infrared or depth. In this article, we investigate this latter scenario assuming that a low-resolution depth camera is used to perform face recognition in an uncooperative context. To this end, we propose, first, to automatically select a set of frames from the depth sequence of the camera because they provide a good view of the face in terms of pose and distance. Then, we design a progressive refinement approach to reconstruct a higher-resolution model from the selected low-resolution frames. This process accounts for the anisotropic error of the existing points in the current 3D model and the points in a newly acquired frame so that the refinement step can progressively adjust the point positions in the model using a Kalman-like estimation. The quality of the reconstructed model is evaluated by considering the error between the reconstructed models and their corresponding high-resolution scans used as ground truth. In addition, we performed face recognition using the reconstructed models as probes against a gallery of reconstructed models and a gallery with high-resolution scans. The obtained results confirm the possibility to effectively use the reconstructed models for the face recognition task.
关键词： anisotropic error,3D reconstruction,3D face recognition,Depth data
更新于2025-09-19 17:15:36
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Investigation of shutter scan acquisition parameters in a prototype chest digital tomosynthesis system
摘要： A shutter scan acquisition (SSA) method is proposed to reduce patient exposure dose in a chest digital tomosynthesis system. Projections obtained using the SSA constitute a combination of truncated and non-truncated projections. The truncated projections are images in which the lung field is set within a region-of-interest (ROI), and the non-truncated projections are full images in which the ROI is not set at all. We proposed a shutter weighting factor (SWF) as an acquisition parameter for SSA. We call the number of truncated projections divided by the number of non-truncated projections as SWF. We used a prototype CDT system and the LUNGMAN phantom with 8 and 10 mm lung nodules. 81 projections were obtained using SSA in five sets according to the SWFs. The image quality was quantified based on the contrast-to-noise ratio (CNR). We also calculated the figure of merit (FOM) to determine the proper acquisition parameters of the five sets. Both the CNR and FOM values of the 8 mm lung nodule in the selected ROI increased with increases of the SWF. However, the CNR value of the 10 mm lung nodule outside the ROI decreased with increases of the SWF, while the FOM value was maximized when the SWF was 3.05. We investigated the effect of the composition ratio of the truncated and non-truncated projections on the reconstructed images of the SSA based on the FOM values. In conclusion, we determined the proper SSA parameters in a prototype CDT system.
关键词： Digital tomosynthesis,Dose reduction method,Region of interest reconstruction,Shutter scan acquisition
更新于2025-09-19 17:15:36
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Landslide Inventory Mapping From Bitemporal Images Using Deep Convolutional Neural Networks
摘要： Most of the approaches used for Landslide inventory mapping (LIM) rely on traditional feature extraction and unsupervised classification algorithms. However, it is difficult to use these approaches to detect landslide areas because of the complexity and spatial uncertainty of landslides. In this letter, we propose a novel approach based on a fully convolutional network within pyramid pooling (FCN-PP) for LIM. The proposed approach has three advantages. First, this approach is automatic and insensitive to noise because multivariate morphological reconstruction is used for image preprocessing. Second, it is able to take into account features from multiple convolutional layers and explore efficiently the context of images, which leads to a good tradeoff between wider receptive field and the use of context. Finally, the selected PP module addresses the drawback of global pooling employed by convolutional neural network, FCN, and U-Net, and, thus, provides better feature maps for landslide areas. Experimental results show that the proposed FCN-PP is effective for LIM, and it outperforms the state-of-the-art approaches in terms of five metrics, Precision, Recall, Overall Error, F-score, and Accuracy.
关键词： landslide inventory mapping (LIM),multivariate morphological reconstruction (MMR),Change detection,deep convolutional network
更新于2025-09-19 17:15:36
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[IEEE 2018 IEEE International Ultrasonics Symposium (IUS) - Kobe, Japan (2018.10.22-2018.10.25)] 2018 IEEE International Ultrasonics Symposium (IUS) - A Compressed Sensing Based Miniaturized Photoacoustic Imaging System
摘要： Compressed Sensing Based Photoelectric Imaging System
关键词： Photoelectric Imaging,Image Reconstruction,Signal Processing,Compressed Sensing
更新于2025-09-19 17:15:36