Motion-compensated PET of awake animals has the potential to greatly improve translational neurological investigations by enabling brain function to be studied during learning tasks and complex behaviors. Previously w...
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ISBN:
(纸本)9781467320306;9781467320283
Motion-compensated PET of awake animals has the potential to greatly improve translational neurological investigations by enabling brain function to be studied during learning tasks and complex behaviors. Previously we have demonstrated the feasibility of performing motion-compensated brain PET on rodents, obtaining the necessary head motion data using marker-based techniques. However, markerless motion tracking would simplify animal experiments and potentially provide more accurate pose estimates over a greater range of motion. Previously we have described a markerless stereo motion tracking system and associated algorithms and validated the approach in phantoms. In this work we performed a pilot study to demonstrate motion-compensated F-18-FDG brain imaging in an awake, unrestrained rat using head pose measurements obtained from the markerless tracking system. Motion compensation clearly worked, resulting in easily identifiable structures in the head. However, it was also obvious that considerable residual error remained after correction. Post analysis of the motion estimates indicated that the residual error was the result of occasional spurious pose estimates, most likely caused by features on non-rigid parts of the head contributing to the pose estimation. Moreover, the line-of-response rebinning used for motion correction resulted in a large proportion of lost events, leading to noisy and inconsistent projection data. The latter is avoided by using a direct list mode reconstruction. In summary, markerless tracking continues to show promise for motion-compensated imaging of awake animals, but further optimization is required to match the accuracy and consistency of marker-based tracking.
This paper examines compressed sensing (CS) based image formation of synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR) data for sparse scenes containing moving targets. We consider basis misma...
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This paper examines compressed sensing (CS) based image formation of synthetic aperture radar (SAR) and inverse synthetic aperture radar (ISAR) data for sparse scenes containing moving targets. We consider basis mismatch for the case when the basis used for reconstruction is different from the actual one in which the reconstructed data are sparse. We use orthogonal matching pursuit (OMP) algorithm for reconstruction and show using simulated data that error between original and reconstructed data increases in presence of basis mismatch. We also show that a certain level of basis mismatch in range velocity, positions and chirp rate is acceptable to achieve reasonable image formation.
Joint routing and compression has been the research hotspot in practical sensor networks. Compressed sensing provides a radically different view of the structure of data and a promising new approach for jointly acquir...
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ISBN:
(纸本)9781467301732
Joint routing and compression has been the research hotspot in practical sensor networks. Compressed sensing provides a radically different view of the structure of data and a promising new approach for jointly acquiring and aggregating datafrom distributed data sources. Therefore, the random routing algorithm is proposed combined with compressive sensing for energy efficient data gathering in rhombic-deployed sensor networks, which satisfies the basic principles of compressed sensing, and can effective reconstruct the original signal. The performance of reconstruction on the basis of reconstruction error, energy consumption, and running time of datareconstruction is analyzed. The experiment results validate its rationality and efficiency.
At KIT we are developing a 3D Ultrasound Computer Tomograph (USCT) for breast cancer detection. Our current reconstruction algorithm, Synthetic Aperture Focussing Technique (SAFT) assumes single scattering for the rec...
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At KIT we are developing a 3D Ultrasound Computer Tomograph (USCT) for breast cancer detection. Our current reconstruction algorithm, Synthetic Aperture Focussing Technique (SAFT) assumes single scattering for the reconstruction of 3D images from the measured data. Higher order reflections cause artefacts in the reconstruction.
Using of passive seismic observations to detect a reservoir is a new direction of prospecting and exploration of hydrocarbons. In order to identify thin reservoir model we applied the modification of Gaussian eliminat...
Using of passive seismic observations to detect a reservoir is a new direction of prospecting and exploration of hydrocarbons. In order to identify thin reservoir model we applied the modification of Gaussian elimination method in conditions of incomplete synthetic data. Because of the singularity of a matrix conventional method does not work. Therefore structural algorithm has been developed by analyzing the given model as a complex model. Numerical results demonstrate of its advantage compared with usual way of solution. We conclude that the gas reservoir is reconstructed by retrieving of the image of encasing shale beneath it.
Estimating the level set of a signal from measurements is a task that arises in a variety of fields, including medical imaging, astronomy, and digital elevation mapping. Motivated by scenarios where accurate and compl...
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Estimating the level set of a signal from measurements is a task that arises in a variety of fields, including medical imaging, astronomy, and digital elevation mapping. Motivated by scenarios where accurate and complete measurements of the signal may not available, we examine here a simple procedure for estimating the level set of a signal from highly incomplete measurements, which may additionally be corrupted by additive noise. The proposed procedure is based on box-constrained Total variation (Tv) regularization. We demonstrate the performance of our approach, relative to existing state-of-the-art techniques for level set estimation from compressive measurements, via several simulation examples.
Although wireless sensor networks (WSNs) are powerful in monitoring physical events, the data collected from a WSN are almost always incomplete if the surveyed physical event spreads over a wide area. The reason for t...
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Although wireless sensor networks (WSNs) are powerful in monitoring physical events, the data collected from a WSN are almost always incomplete if the surveyed physical event spreads over a wide area. The reason for this incompleteness is twofold: i) insufficient network coverage and ii) data aggregation for energy saving. Whereas the existing recovery schemes only tackle the second aspect, we develop Dual-lEvel Compressed Aggregation (DECA) as a novel framework to address both aspects. Specifically, DECA allows a high fidelity recovery of a widespread event, under the situations that the WSN only sparsely covers the event area and that an in-network data aggregation is applied for traffic reduction. Exploiting both the low-rank nature of real-world events and the redundancy in sensory data, DECA combines matrix completion with a fine-tuned compressed sensing technique to conduct a dual-level reconstruction process. We demonstrate that DECA can recover a widespread event with less than 5% of the data (with respect to the dimension of the event) being collected. Performance evaluation based on both synthetic and real data sets confirms the recovery fidelity and energy efficiency of our DECA framework.
In this work we present a natural user interface system using hand gestures to provide touchless control of 3D visualization software using the Microsoft Kinect device. Kinect is a relatively low-cost device developed...
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ISBN:
(纸本)9780203181416
In this work we present a natural user interface system using hand gestures to provide touchless control of 3D visualization software using the Microsoft Kinect device. Kinect is a relatively low-cost device developed by Microsoft for the gaming industry to provide controller-free gaming, but it has potential applications in many other areas, such as: datavisualization, augmented reality, accessibility and robotics. Although our solution can be used with any 3D software, the present work is primarily focused in one particular application which is the visualization of 3D medical images during a surgical procedure. The operating room is a cleansed and sterilized environment and the contact of the surgeon with traditional computer interfaces (like mouse and keyboard) could lead to contamination increasing the risk of patients infection. A touchless interface is an ideal solution since it does not demand any physical contact and still can provide the necessary control features. For the visualization of 3D medical images, we used the Invesalius software that provides 3D reconstruction of medical images with features that enable the rapid prototyping of medical models and provides high-quality visualization of 3D volumes. This software is open-source, cross-platform, multi-language and is freely available. Using open-source software libraries and image processing techniques, we implemented the hands tracking and gestures recognition from the images provided by the Kinect device and enabled the surgeon to successfully navigate through the image.
3D city models typically consist of thousands of buildings in different types. We usually reconstruct these buildings automatically from high-resolution satellite or airborne imagery. However, for detailed roof recons...
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3D city models typically consist of thousands of buildings in different types. We usually reconstruct these buildings automatically from high-resolution satellite or airborne imagery. However, for detailed roof reconstruction, 2D information offered by imagery data is not enough while DSM data is necessary. In this paper, we propose a novel level set framework for 3D building models in LOD2 with geometry structure of typical roofs. Local information is introduced towards multiphase and multichannel level set method. Its energy function is minimized when each part of roof data corresponds to the same normal vector as feature values for level set segmentation. The advantage of this method is that for complex building models, roof primitives as well as roof topology graph can be extracted from high-resolution DSM data with high accuracy, evaluated by completeness of segmentation and RMSE of 3D reconstruction. Thus, LOD2 building models can be reconstructed automatically with good performance. The very promising experimental results demonstrate the potentials of our method for large-scale building reconstruction in LOD2.
A new algorithm is presented for efficiently solving imagereconstruction problems that arise in partially parallel magnetic resonance imaging. This algorithm minimizes an objective function of the form φ(Bu) + 1/2‖...
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A new algorithm is presented for efficiently solving imagereconstruction problems that arise in partially parallel magnetic resonance imaging. This algorithm minimizes an objective function of the form φ(Bu) + 1/2‖F_pSu - f‖~2, where φ is the regularization term which may be nonsmooth. In imagereconstruction, the φ term corresponds to total variation smoothing and/or L1 regularization term. The least square term 1/2‖F_pSu - f‖~2 is the fidelity term. In our application, f represents undersampled datafrom a partially parallel imaging (PPI) system. The proposed algorithm is a generalization of the Bregman operator splitting algorithm with variable stepsize (BOSvS) in which the previous Barzilai-Borwein (BB) step is replaced by a cyclic BB (CBB) step, and an L1 term Ψ is added to the energy function. Experimental results on clinical partially parallel imaging data are given.
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