Reflectance Transformation Imaging Method for Large-Scale Objects

2016 ◽  
Author(s):  
Yong Hwi Kim ◽  
Junho Choi ◽  
Yong Yi Lee ◽  
Bilal Ahmed ◽  
Kwan H. Lee
Keyword(s):  
Large Scale ◽  
Imaging Method ◽  
Reflectance Transformation Imaging

scholarly journals Target-oriented Gaussian beam migration using a modified ray tracing scheme

2019 ◽  
Vol 16 (6) ◽  
pp. 1301-1319 ◽  
Author(s):  
Rui Zhang ◽  
Jian-Ping Huang ◽  
Su-Bin Zhuang ◽  
Zhen-Chun Li
Keyword(s):  
Gaussian Beam ◽  
Ray Tracing ◽  
Large Scale ◽  
High Efficiency ◽  
Complex Structure ◽  
Back Propagation ◽  
Imaging Method ◽  
Computation Efficiency ◽  
Simple Implementation ◽  
Gaussian Beam Migration

Abstract For large-scale 3D seismic data, target-oriented reservoir imaging is more attractive than conventional full-volume migration, in terms of computation efficiency. Gaussian beam migration (GBM) is one of the most robust depth imaging method, which not only keeps the advantages of ray methods, such as high efficiency and flexibility, but also allows us to solve caustics and multipathing problems. But conventional Gaussian beam migration requires slant stack for prestack data, and ray tracing from beam center location to subsurface, which is not easy to be directly applied for target-oriented imaging. In this paper, we modify the conventional Gaussian beam migration scheme, by shooting rays from subsurface image points to receivers to implement wavefield back-propagation. This modification helps us to achieve a better subsurface illumination in complex structure and allows simple implementation for target reservoir imaging. Significantly, compared with the wavefield-based GBM, our method does not reconstruct the subsurface snapshots, which has higher efficiency. But the proposed method is not as efficient as the conventional Gaussian beam migration. Synthetic and field data examples demonstrate the validity and the target-oriented imaging capability of our method.

scholarly journals RTI metoda jako způsob digitalizace kulturního dědictví

2022 ◽  
Vol 58 (2) ◽  
pp. 32-38
Author(s):  
Barbora Borůvková ◽  
Klára Burianová
Keyword(s):  
Imaging Method ◽  
Technological Equipment ◽  
Cultural Institutions ◽  
Price Levels ◽  
Technological Developments ◽  
Reflectance Transformation Imaging

Current technological developments offer an inexhaustible number of procedures for digitization. However, technological equipment intended for teams in professional laboratories reaches price levels that cultural institutions often do not have enough finances. Procedures and methods using equipment, which institutions often already own or are not so expensive to acquire, come to the fore. One of them is the RTI (Reflectance Transformation Imaging) method, which creates a spatial relief composed of a sequence of images with visible lighting. The RTI method is very successful in depicting illegible or wiped details and is already widely used in archaeology.

scholarly journals Diagnostic and Complication Rate of Image-guided Lung Biopsies in Raigmore Hospital, Inverness: A Retrospective Re-audit

2012 ◽  
Vol 1 (1) ◽  
pp. 1-7
Author(s):  
S Khadka
Keyword(s):  
Complication Rate ◽  
Large Scale ◽  
Histological Study ◽  
British Thoracic Society ◽  
Chest Drain ◽  
Imaging Method ◽  
Ct Guided ◽  
Image Guided ◽  
Bronchoscopic Biopsy ◽  
Lung Biopsies

Background: Suspected lung malignancies that are deemed inaccessible by bronchoscopic biopsy undergo image-guided biopsies to obtain samples for histological study. A previous audit performed in 2008 assessed the diagnostic and complication rate of computed tomography (CT)-guided lung biopsies. This retrospective re-audit aimed to reassess the lung biopsies done in 2010. Standards: British thoracic society guidelines for Radiologically guided lung biopsy. Materials and Method: All patients who underwent image-guided lung biopsies at Raigmore Hospital, Inverness, in 2010 were included in the study. The imaging was either CT or ultrasound (US) and either fine-needle aspirate or core-biopsy samples were collected. Information on diagnostic rate, complications such as pneumothorax and haemoptysis, age, sex, size and depth of lesion were collected. Results: 108 biopsies were obtained by image guided lung biopsies from 101 patients during 2010. 80 lesions were malignant, 19 were benign and 2 undiagnostic. 7 biopsies had to be repeated. Diagnostic accuracy was 91.7% (99 biopsies). 21 patients (19.4%) had pneumothorax. 19 suffered from small pneumothorax while 2 (1.9%) required chest drain. 7 patients (6.5%) developed minor haemoptysis. Only 3 out of 108 biopsies were done under US scan. Conclusion: The diagnostic and pneumothorax rates are well within British thoracic society guidelines, whilst the minor haemoptysis rate is slightly higher. Further large-scale studies are indicated to assess the possible role of ultrasound as a potential imaging method for pleural based lung biopsies. DOI: http://dx.doi.org/10.3126/njr.v1i1.6315 Nepalese Journal of Radiology Vol.1(1): 1-7

Lattice Imaging of Silicide-Silicon Interfaces

1981 ◽  
Vol 10 ◽  
Author(s):  
L. J. Chen ◽  
J. W. Mayer ◽  
K. N. Tu ◽  
T. T. Sheng
Keyword(s):  
Large Scale ◽  
Amorphous Layer ◽  
Atomic Scale ◽  
Imaging Method ◽  
Lattice Imaging ◽  
Cross Sectional ◽  
Defect Clusters ◽  
Direct Lattice ◽  
Curved Interface ◽  
Boundary Lines

The interfaces of both epitaxial and non-epitaxial silicides and silicon were investigated by the direct lattice imaging method using cross-sectional samples. Non-epitaxial CoSi2 on silicon was observed to have a curved interface. Epitaxial CoSi2 , however, was found to be smooth within a facet. No evidence of an amorphous layer at the interface was obtained.Epitaxial NiSi2 on Si(001) was found to be heavily faceted. The facets are on {111} and {100} planes with the former more frequently observed. The interface between Si(111) and NiSi2 is also faceted but less so than that for Si(001). The interface is very rough on a large scale. Straight boundary lines corresponding to faceted planes were observed which indicated that the interfaces on an atomic scale were quite smooth. Defect clusters and planar defects were also observed at the interfaces.

scholarly journals Efficient Parameter Estimation for Sparse SAR Imaging Based on Complex Image and Azimuth-Range Decouple

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4549
Author(s):  
Mingqian Liu ◽  
Bingchen Zhang ◽  
Zhongqiu Xu ◽  
Yirong Wu
Keyword(s):  
Parameter Estimation ◽  
Large Scale ◽  
Regularization Parameter ◽  
Estimation Method ◽  
Imaging Method ◽  
Adaptive Parameter ◽  
Processing Theory ◽  
Complex Image ◽  
Sar Imaging ◽  
Observation Matrix

Sparse signal processing theory has been applied to synthetic aperture radar (SAR) imaging. In compressive sensing (CS), the sparsity is usually considered as a known parameter. However, it is unknown practically. For many functions of CS, we need to know this parameter. Therefore, the estimation of sparsity is crucial for sparse SAR imaging. The sparsity is determined by the size of regularization parameter. Several methods have been presented for automatically estimating the regularization parameter, and have been applied to sparse SAR imaging. However, these methods are deduced based on an observation matrix, which will entail huge computational and memory costs. In this paper, to enhance the computational efficiency, an efficient adaptive parameter estimation method for sparse SAR imaging is proposed. The complex image-based sparse SAR imaging method only considers the threshold operation of the complex image, which can reduce the computational costs significantly. By utilizing this feature, the parameter is pre-estimated based on a complex image. In order to estimate the sparsity accurately, adaptive parameter estimation is then processed in the raw data domain, combining with the pre-estimated parameter and azimuth-range decouple operators. The proposed method can reduce the computational complexity from a quadratic square order to a linear logarithm order, which can be used in the large-scale scene. Simulated and Gaofen-3 SAR data processing results demonstrate the validity of the proposed method.

scholarly journals GO_3D_OBS: the multi-parameter benchmark geomodel for seismic imaging method assessment and next-generation 3D survey design (version 1.0)

2021 ◽  
Vol 14 (3) ◽  
pp. 1773-1799
Author(s):  
Andrzej Górszczyk ◽  
Stéphane Operto
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Survey Design ◽  
Regional Scale ◽  
Leading Edge ◽  
Imaging Method ◽  
High Resolution Imaging ◽  
Ocean Bottom ◽  
Next Generation ◽  
Resolution Imaging

Abstract. Detailed reconstruction of deep crustal targets by seismic methods remains a long-standing challenge. One key to address this challenge is the joint development of new seismic acquisition systems and leading-edge processing techniques. In marine environments, controlled-source seismic surveys at a regional scale are typically carried out with sparse arrays of ocean bottom seismometers (OBSs), which provide incomplete and down-sampled subsurface illumination. To assess and minimize the acquisition footprint in high-resolution imaging process such as full waveform inversion, realistic crustal-scale benchmark models are clearly required. The deficiency of such models prompts us to build one and release it freely to the geophysical community. Here, we introduce GO_3D_OBS – a 3D high-resolution geomodel representing a subduction zone, inspired by the geology of the Nankai Trough. The 175km×100km×30km model integrates complex geological structures with a viscoelastic isotropic parameterization. It is defined in the form of a uniform Cartesian grid containing ∼33.6e9 degrees of freedom for a grid interval of 25 m. The size of the model raises significant high-performance computing challenges to tackle large-scale forward propagation simulations and related inverse problems. We describe the workflow designed to implement all the model ingredients including 2D structural segments, their projection into the third dimension, stochastic components, and physical parameterization. Various wavefield simulations that we present clearly reflect in the seismograms the structural complexity of the model and the footprint of different physical approximations. This benchmark model is intended to help to optimize the design of next-generation 3D academic surveys – in particular, but not only, long-offset OBS experiments – to mitigate the acquisition footprint during high-resolution imaging of the deep crust.

scholarly journals In Situ Investigation of the 3D Mechanical Microstructure at Nanoscale: Nano-CT Imaging Method of Local Small Region in Large Scale Sample

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Bo Dong ◽  
Feng Xu ◽  
Xiao-fang Hu ◽  
Hong-yan Qu ◽  
Dan Kang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Small Region ◽  
Projection Data ◽  
Imaging Method ◽  
Reconstruction Method ◽  
Localization Property ◽  
Local Tomography ◽  
In Situ Investigation

To investigate the local micro-/nanoscale region in a large scale sample, an image reconstruction method for nanometer computed tomography (nano-CT) was proposed in this paper. In the algorithm, wavelets were used to localize the filtered-backprojection (FBP) algorithm because of its space-frequency localization property. After the implementation of the algorithm, two simulation local reconstruction experiments were performed to confirm its effectiveness. Three evaluation criteria were used in the experiments to judge the quality of the reconstructed images. The experimental results showed that the algorithm proposed in this paper performed best because (1) the quality of its results had improved 20%–30% compared to the results of FBP and 10%–30% compared to the results of another wavelet algorithm; (2) the new algorithm was stable under different circumstances. Besides, an actual reconstruction experiment was performed using real projection data that had been collected in a CT experiment. Two-dimensional (2D) and three-dimensional (3D) images of the sample were reconstructed. The microstructure of the sample could be clearly observed in the reconstructed images. Since much attention has been directed towards the nano-CT technique to investigate the microstructure of materials, this new wavelet-based local tomography algorithm could be considered as a meaningful effort.

scholarly journals Volumetric Two-photon Imaging of Neurons Using Stereoscopy (vTwINS)

2016 ◽  
Author(s):  
Alexander Song ◽  
Adam S. Charles ◽  
Sue Ann Koay ◽  
Jeff L. Gauthier ◽  
Stephan Y. Thiberge ◽  
...  
Keyword(s):  
Calcium Imaging ◽  
Laser Scanning ◽  
Large Scale ◽  
Laser Scanning Microscopy ◽  
Frame Rate ◽  
Neural Population ◽  
Imaging Method ◽  
Two Photon ◽  
Photon Imaging ◽  
Two Photon Imaging

AbstractTwo-photon laser scanning microscopy of calcium dynamics using fluorescent indicators is a widely used imaging method for large scale recording of neural activity in vivo. Here we introduce volumetric Two-photon Imaging of Neurons using Stereoscopy (vTwINS), a volumetric calcium imaging method that employs an elongated, V-shaped point spread function to image a 3D brain volume. Single neurons project to spatially displaced image pairs in the resulting 2D image, and the separation distance between images is proportional to depth in the volume. To demix the fluorescence time series of individual neurons, we introduce a novel orthogonal matching pursuit algorithm that also infers source locations within the 3D volume. We illustrate vTwINS by imaging neural population activity in mouse primary visual cortex and hippocampus. Our results demonstrate that vTwINS provides an effective method for volumetric two-photon calcium imaging that increases the number of neurons recorded while maintaining a high frame-rate.

Sign in / Sign up

Export Citation Format

Share Document