scholarly journals Tests of a novel imaging algorithm to localize hidden objects or cavities with muon radiography

2018 ◽  
Vol 377 (2137) ◽  
pp. 20180063 ◽  
Author(s):  
L. Bonechi ◽  
G. Baccani ◽  
M. Bongi ◽  
D. Brocchini ◽  
N. Casagli ◽  
...  
Keyword(s):  
Laboratory Tests ◽  
Three Dimensional ◽  
Cosmic Ray ◽  
Real Data ◽  
Test Results ◽  
Back Projection ◽  
Imaging Algorithm ◽  
Muon Radiography ◽  
Points Of View ◽  
Large Material

A novel algorithm developed within muon radiography to localize objects or cavities hidden inside large material volumes was recently proposed by some of the authors (Bonechi et al. 2015 J. Instrum. 10 , P02003 ( doi:10.1088/1748-0221/10/02/P02003 )). The algorithm, based on muon back projection, helps to estimate the three-dimensional position and the transverse extension of detected objects without the need for measurements from different points of view, which would be required to make a triangulation. This algorithm can now be tested owing to the availability of real data collected both in laboratory tests and from real-world measurements. The methodology and some test results are presented in this paper. This article is part of the Theo Murphy meeting issue ‘Cosmic-ray muography’.

scholarly journals Correction to “Three-dimensional computational axial tomography scan of a volcano with cosmic ray muon radiography”

2011 ◽  
Vol 116 (B3) ◽  
Author(s):  
Hiroyuki K. M. Tanaka ◽  
Hideaki Taira ◽  
Tomihisa Uchida ◽  
Manobu Tanaka ◽  
Minoru Takeo ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Cosmic Ray ◽  
Axial Tomography ◽  
Muon Radiography ◽  
Tomography Scan

Three-dimensional Density Reconstruction Analysis Method for Omni-directional Muography

2020 ◽  
Author(s):  
Seigo Miyamoto ◽  
Shogo Nagahara
Keyword(s):  
Spatial Resolution ◽  
Three Dimensional ◽  
Cosmic Ray ◽  
Inversion Method ◽  
Density Structure ◽  
Back Projection ◽  
Analysis Method ◽  
Filtered Back Projection ◽  
Linear Inversion ◽  
Reconstruction Methods

<p>Muography is the technique to observe the inner density structure of volcano by using cosmic-ray muons. In previous study, three-dimensional density reconstruction was attempted by using muography data from multiple directions (Tanaka et al., 2010, Rosas-Carbajal et al., 2017), but they could only get a few hundred meters of spatial resolution. To improve the spatial resolution, Nagahara and Miyamoto (2018) suggested omni-directional muography, putting ten or more observation points to surround the volcano.</p><p>  There are two types of three-dimensional density reconstruction methods from omni-directional muography observations, the linear inversion method (Rosas-Carbajal et al., 2017) and the filtered back projection (FBP) method (Nagahara and Miyamoto, 2018). The former is applicable even when the number of observation points is small, but requires many arbitrary parameters, while the latter has the characteristic that no arbitrary parameters are required but a certain number of observation points is required.</p><p>In this presentation, we show the results of a comparison between the two methods in simulation.</p>

scholarly journals Three-dimensional computational axial tomography scan of a volcano with cosmic ray muon radiography

2010 ◽  
Vol 115 (B12) ◽  
Author(s):  
Hiroyuki K. M. Tanaka ◽  
Hideaki Taira ◽  
Tomihisa Uchida ◽  
Manobu Tanaka ◽  
Minoru Takeo ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Cosmic Ray ◽  
Axial Tomography ◽  
Muon Radiography ◽  
Tomography Scan

scholarly journals Focusing High-Squint Synthetic Aperture Radar Data Based on Factorized Back-Projection and Precise Spectrum Fusion

2019 ◽  
Vol 11 (24) ◽  
pp. 2885
Author(s):  
Lei Ran ◽  
Zheng Liu ◽  
Rong Xie ◽  
Lei Zhang
Keyword(s):  
Synthetic Aperture Radar ◽  
Real Data ◽  
Radar Data ◽  
Synthetic Aperture ◽  
Back Projection ◽  
Motion Error ◽  
Synthetic Aperture Radar Data ◽  
Imaging Algorithm ◽  
Polar Coordinate ◽  
Aperture Radar

This paper presents a microwave imaging algorithm for high-squint airborne synthetic aperture radar (SAR), which combines back-projection and spectrum fusion together. Two spectrum center functions are proposed for linear and nonlinear trajectories respectively, which are the main contributions of this paper, and not considered in conventional work for high-squint SAR. For linear trajectory, the whole aperture data is first divided into sub-apertures with equal length, and the sub-aperture data is backprojected to a unified polar coordinate to generate multiple low-resolution sub-images. Then, these sub-images are corrected by an accurate spectrum center function, which is caused by the presence of squint angle. After spectrum center correction, spectrums of these sub-images can be coherently connected in cross-range wavenumber domain, generating the whole aperture spectrum. Next, the full-resolution image can be obtained by cross-range Fourier transform. For nonlinear trajectory, the deviations introduce extra spectrum shift, which degrades the focusing performance. Another spectrum center function is proposed according to angular-variant motion-error model, which helps to perform precise spectrum fusion. The proposed imaging algorithm is called high-squint accelerated factorized back-projection (HS-AFBP), and it helps to improve the focusing precision. Both the simulation and real data experiments validate the effectiveness of the proposed HS-AFBP algorithm.

scholarly journals Feasibility of three-dimensional density tomography using dozens of muon radiographies and filtered back projection for volcanos

2018 ◽  
Vol 7 (4) ◽  
pp. 307-316 ◽  
Author(s):  
Shogo Nagahara ◽  
Seigo Miyamoto
Keyword(s):  
Three Dimensional ◽  
Cosmic Ray ◽  
Exposure Period ◽  
Effective Area ◽  
Scoria Cone ◽  
Inversion Method ◽  
Back Projection ◽  
Initial Model ◽  
Filtered Back Projection ◽  
Using Data

Abstract. This study is the first trial to apply the method of filtered back projection (FBP) to reconstruct three-dimensional (3-D) bulk density images via cosmic-ray muons. We also simulated three-dimensional reconstruction image with dozens of muon radiographies for a volcano using the FBP method and evaluated its practicality. The FBP method is widely used in X-ray and CT image reconstruction but has not been used in the field of muon radiography. One of the merits of using the FBP method instead of the ordinary inversion method is that it does not require an initial model, while ordinary inversion analysis needs an initial model. We also added new approximation factors by using data on mountain topography in existing formulas to successfully reduce systematic reconstruction errors. From a volcanic perspective, lidar is commonly used to measure and analyze mountain topography. We tested the performance and applicability to a model of Omuroyama, a monogenetic scoria cone located in Shizuoka, Japan. As a result, it was revealed that the density difference between the original and reconstructed images depended on the number of observation points and the accidental error caused by muon statistics depended on the multiplication of total effective area and exposure period. Combining all of the above, we established how to evaluate an observation plan for volcanos using dozens of muon radiographies.

A linearity test for thick specimens imaged by HVEM over a 180° angular range

1991 ◽  
Vol 49 ◽  
pp. 552-553
Author(s):  
Yu Liu
Keyword(s):  
Phase Contrast ◽  
Three Dimensional ◽  
Angular Range ◽  
Two Dimensional ◽  
Back Projection ◽  
Line Integral ◽  
Exponential Law ◽  
Transmission Electron ◽  
Absorption Law ◽  
Linearity Test

The image obtained in a transmission electron microscope is the two-dimensional projection of a three-dimensional (3D) object. The 3D reconstruction of the object can be calculated from a series of projections by back-projection, but this algorithm assumes that the image is linearly related to a line integral of the object function. However, there are two kinds of contrast in electron microscopy, scattering and phase contrast, of which only the latter is linear with the optical density (OD) in the micrograph. Therefore the OD can be used as a measure of the projection only for thin specimens where phase contrast dominates the image. For thick specimens, where scattering contrast predominates, an exponential absorption law holds, and a logarithm of OD must be used. However, for large thicknesses, the simple exponential law might break down due to multiple and inelastic scattering.

scholarly journals Precise point positioning with GPS and Galileo broadcast ephemerides

GPS Solutions ◽  
2021 ◽  
Vol 25 (2) ◽  
Author(s):  
Luca Carlin ◽  
André Hauschild ◽  
Oliver Montenbruck
Keyword(s):  
Precise Point Positioning ◽  
Three Dimensional ◽  
Test Results ◽  
Process Noise ◽  
Functional Models ◽  
Ambiguity Estimation ◽  
Point Positioning ◽  
And Performance ◽  
Range Error ◽  
Space Range

AbstractFor more than 20 years, precise point positioning (PPP) has been a well-established technique for carrier phase-based navigation. Traditionally, it relies on precise orbit and clock products to achieve accuracies in the order of centimeters. With the modernization of legacy GNSS constellations and the introduction of new systems such as Galileo, a continued reduction in the signal-in-space range error (SISRE) can be observed. Supported by this fact, we analyze the feasibility and performance of PPP with broadcast ephemerides and observations of Galileo and GPS. Two different functional models for compensation of SISREs are assessed: process noise in the ambiguity states and the explicit estimation of a SISRE state for each channel. Tests performed with permanent reference stations show that the position can be estimated in kinematic conditions with an average three-dimensional (3D) root mean square (RMS) error of 29 cm for Galileo and 63 cm for GPS. Dual-constellation solutions can further improve the accuracy to 25 cm. Compared to standard algorithms without SISRE compensation, the proposed PPP approaches offer a 40% performance improvement for Galileo and 70% for GPS when working with broadcast ephemerides. An additional test with observations taken on a boat ride yielded 3D RMS accuracy of 39 cm for Galileo, 41 cm for GPS, and 27 cm for dual-constellation processing compared to a real-time kinematic reference solution. Compared to the use of process noise in the phase ambiguity estimation, the explicit estimation of SISRE states yields a slightly improved robustness and accuracy at the expense of increased algorithmic complexity. Overall, the test results demonstrate that the application of broadcast ephemerides in a PPP model is feasible with modern GNSS constellations and able to reach accuracies in the order of few decimeters when using proper SISRE compensation techniques.

Sign in / Sign up

Export Citation Format

Share Document