scholarly journals Deabsorption prestack time migration from rugged topography

2021 ◽  
Vol 18 (2) ◽  
pp. 291-303
Author(s):  
Changshan Han ◽  
Linong Liu ◽  
Zelin Liu ◽  
Zhengwei Li
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Signal To Noise ◽  
Time Migration ◽  
Q Model ◽  
Rugged Topography ◽  
Migration Method ◽  
Prestack Time Migration ◽  
The Common ◽  
Quality Factor Q

Abstract We developed a modified topography prestack time migration (PSTM) scheme that can improve the imaging resolution by applying effective Q to topography migration. The computation of the traveltime at each imaging location in the migration is based on the floating datum smoothed by rugged topography. Unlike the common quality factor Q, the effective Q only determines the frequency-dependent amplitude and the traveltime at a single imaging location, which enables us to establish a Q model in an inhomogeneous medium. Hence, we can acquire the effective Q using a scanning technology according to the width of the frequency band and signal-to-noise ratio of the imaging gathers. The proposed migration method can be integrated into the conventional topography migration workflow. Synthetic and three-dimensional (3D) field datasets indicate that the proposed deabsorption PSTM from rugged topography is effective.

Prestack time migration by common-migrated-reflector-element stacking

Geophysics ◽  
2012 ◽  
Vol 77 (3) ◽  
pp. S73-S82 ◽  
Author(s):  
Sergius Dell ◽  
Dirk Gajewski ◽  
Claudia Vanelle
Keyword(s):  
Initial Time ◽  
Depth Migration ◽  
Time Migration ◽  
Migration Method ◽  
Prestack Time Migration ◽  
The Common ◽  
A New Technique ◽  
New Formulation ◽  
Time Image ◽  
Migration Velocities

Time migration is an attractive tool to produce a subsurface image because it is faster and less sensitive to velocities errors than depth migration. However, a highly focused time image is only achievable with well-determined time-migration velocities. Therefore, a refinement of the initial time-migration velocities often is required. We introduced a new technique for prestack time migration, based on the common-migrated-reflector-element stack of common scatterpoint gathers, including an automatic update of time-migration velocities. The common scatterpoint gathers are generated using a new formulation of the double-square-root equation that is parametrized with the common-offset apex time. The common-migrated-reflector-element stack is a multiparameter stacking technique based on the Taylor expansion of traveltimes of time-migrated reflections in the paraxial vicinity of the image ray. Our 2D synthetic and field data examples demonstrated that the proposed method provides updated time-migration velocities that are more robust and have higher resolution compared with the initial time-migration velocities. The prestack time migration method also showed a clear improvement of the focusing of reflections for such geologic features as faults and salt structures.

Full-azimuth anisotropic prestack time migration in the local-angle domain and its applications on fracture detection

Geophysics ◽  
2015 ◽  
Vol 80 (2) ◽  
pp. C37-C47 ◽  
Author(s):  
Xuekai Sun ◽  
Sam Zandong Sun
Keyword(s):  
Signal To Noise Ratio ◽  
Carbonate Reservoir ◽  
Fracture Detection ◽  
Traveltime Inversion ◽  
Fracture Medium ◽  
Time Migration ◽  
Migration Method ◽  
Prestack Time Migration ◽  
Subsurface Fractures ◽  
Local Angle

Considering that geologic structures disturb prestack amplitude relationships, anisotropic migration is thus advocated not only for extracting azimuth-preserved common image gathers (CIGs), but also for preserving fracture-induced amplitude responses. However, most conventional anisotropic migration methods are hindered by their inefficiency in either modeling azimuthal traveltime variations at large offsets or characterizing subsurface reflections. Given that prestack time migration is widely applied for most practical purposes, we began with reformulations on a quartic traveltime formula, through which a new set of anisotropic parameters was developed. Then, an anisotropic migration method was established in the local-angle domain (LAD) for more reasonable uses of subsurface wavefield information. We also used a traveltime inversion scheme to estimate those anisotropic parameters required by anisotropic migration. Using this methodology on a physical model with a fracture medium, we derived better focused CIGs by thoroughly correcting the anisotropic effects of overburden. As a result, predicted properties of the fracture medium showed fewer interventions of geologic impacts. In a field example, a comprehensive study was performed on a deep carbonate reservoir to examine influences of different anisotropic migration algorithms on ultimate fracture prediction. Comparisons of the signal-to-noise ratio and agreements with formation microimage information reconfirmed the superiority of LAD anisotropic migration in recovering true properties of subsurface fractures, relative to routine methods (i.e., azimuth-sectored migration and anisotropic migration in the surface-offset domain).

Compression of Secondary Ion Microscopy Image Sets Using a Three-dimensional Wavelet Transformation

2000 ◽  
Vol 6 (1) ◽  
pp. 68-75 ◽  
Author(s):  
Martin G. Wolkenstein ◽  
Herbert Hutter
Keyword(s):  
Image Compression ◽  
Wavelet Transformation ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Compression Method ◽  
Signal To Noise ◽  
Microscopy Image ◽  
Image Set ◽  
Ion Microscopy ◽  
Secondary Ion

This article proposes a lossy three-dimensional (3-D) image compression method for 3-D secondary ion microscopy (SIMS) image sets that uses a separable nonuniform 3-D wavelet transform. A typical 3-D SIMS measurement produces relatively large amounts of data which has to be reduced for archivation purposes. Although it is possible to compress an image set slice by slice, more efficient compression can be achieved by exploring the correlation between slices. Compared to different two-dimensional (2-D) image compression methods, compression ratios of the 3-D wavelet method are about four times higher at a comparable peak signal-to-noise ratio (PSNR).

A new method for ultrasonic detection of peel ply at the bondline of out-of-autoclave composite assemblies

2018 ◽  
Vol 53 (2) ◽  
pp. 245-259
Author(s):  
Gary S LeMay ◽  
Davood Askari
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Ultrasonic Pulse ◽  
Woven Fabric ◽  
Material System ◽  
Signal To Noise ◽  
Structural Applications ◽  
Peel Ply ◽  
Noise Ratio ◽  
Out Of Autoclave

Out-of-autoclave materials have long been an established material system for secondary structural applications; however, recent advancements in material properties allow for more advanced structural applications. Even though certain out-of-autoclave properties have achieved parity with autoclaved cured materials, out-of-autoclave materials are cured at reduced temperatures and pressures resulting in less compaction and homogeneity. The consequence is extraneous ultrasonic signals, due to internal reflections and refractions that cause attenuation, potentially masking defects leading to unidentifiable indications. Advanced algorithms were developed to improve the signal to noise ratio between constituents of similar acoustic impedance in bonded out-of-autoclave carbon fiber reinforced polymer assemblies. Conventional ultrasonic nondestructive testing techniques and analysis software cannot consistently achieve signal to noise ratios that meet quantifiable rejection thresholds of accurately sized peel ply inserts at the bonded interface of composite assemblies. Ultrasonic pulse echo with full waveform capture was used to inspect a reference standard with peel ply inserts placed between the adhesive and three-dimensional-woven fabric preform. The ultrasonic signal was produced by a 64 element array transducer with a central frequency of 2.8 MHz. Waveform post-acquisition analysis with post processing software was used to analyze and enhance the signal response between the peel ply and the bondline resulting in the final algorithm. To verify the results, the signal to noise ratio of each insert was calculated for both the raw and processed data. As the measure of detectability, the method relies on principles of statistical measurement to provide an industry standard signal to noise response of 3:1.

scholarly journals Three-Dimensional Imaging via Time-Correlated Single-Photon Counting

2020 ◽  
Vol 10 (6) ◽  
pp. 1930
Author(s):  
Chengkun Fu ◽  
Huaibin Zheng ◽  
Gao Wang ◽  
Yu Zhou ◽  
Hui Chen ◽  
...  
Keyword(s):  
3D Imaging ◽  
Single Photon ◽  
Signal To Noise Ratio ◽  
Photon Counting ◽  
Three Dimensional ◽  
Similarity Index ◽  
Signal To Noise ◽  
Single Photon Counting ◽  
Imaging Results ◽  
Noise Ratio

Three-dimensional (3D) imaging under the condition of weak light and low signal-to-noise ratio is a challenging task. In this paper, a 3D imaging scheme based on time-correlated single-photon counting technology is proposed and demonstrated. The 3D imaging scheme, which is composed of a pulsed laser, a scanning mirror, single-photon detectors, and a time-correlated single-photon counting module, employs time-correlated single-photon counting technology for 3D LiDAR (Light Detection and Ranging). Aided by the range-gated technology, experiments show that the proposed scheme can image the object when the signal-to-noise ratio is decreased to −13 dB and improve the structural similarity index of imaging results by 10 times. Then we prove the proposed scheme can image the object in three dimensions with a lateral imaging resolution of 512 × 512 and an axial resolution of 4.2 mm in 6.7 s. At last, a high-resolution 3D reconstruction of an object is also achieved by using the photometric stereo algorithm.

Compression of Secondary Ion Microscopy Image Sets Using a Three-dimensional Wavelet Transformation

2000 ◽  
Vol 6 (1) ◽  
pp. 68-75
Author(s):  
Martin G. Wolkenstein ◽  
Herbert Hutter
Keyword(s):  
Image Compression ◽  
Wavelet Transformation ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Compression Method ◽  
Signal To Noise ◽  
Microscopy Image ◽  
Image Set ◽  
Ion Microscopy ◽  
Secondary Ion

Abstract This article proposes a lossy three-dimensional (3-D) image compression method for 3-D secondary ion microscopy (SIMS) image sets that uses a separable nonuniform 3-D wavelet transform. A typical 3-D SIMS measurement produces relatively large amounts of data which has to be reduced for archivation purposes. Although it is possible to compress an image set slice by slice, more efficient compression can be achieved by exploring the correlation between slices. Compared to different two-dimensional (2-D) image compression methods, compression ratios of the 3-D wavelet method are about four times higher at a comparable peak signal-to-noise ratio (PSNR).

Three-Dimensional Optical Bit Memory in Sm(DBM)3Phen-Doped and Un-Doped Poly(methyl methacrylate)

2011 ◽  
Vol 284-286 ◽  
pp. 2251-2254
Author(s):  
Zhao Gang Nie ◽  
Xin Zhong Li ◽  
Yu Ping Tai ◽  
Ki Soo Lim ◽  
Myeongkyu Lee
Keyword(s):  
Refractive Index ◽  
Methyl Methacrylate ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Pulsed Laser ◽  
High Signal ◽  
Signal To Noise ◽  
Fluorescent Signal ◽  
Poly Methyl Methacrylate ◽  
Noise Ratio

The feasibility of three-dimensional optical bit memory is demonstrated by using the change of fluorescence and refractive index in Sm(DBM)3Phen-doped and un-doped Poly(methyl methacrylate). After a femtosecond pulsed laser irradiation, a refractive-index bit and a fluorescent bit can be formed at the same position inside the bulk sample. Multilayer patterns recorded by tightly focusing the pulsed laser beam were read out by a reflection-type fluorescent confocal microscope, which can detect the reflection signal and also the fluorescent signal of the stored bits. The signal-to-noise ratio via the two retrieval modes was compared as a function of recording depth. The stored bits were retrieved with a high signal-to-noise ratio in the absence of any crosstalk and the detection of the fluorescent signal enables retrieval of the stored bits with a higher S/N ratio.

scholarly journals Three-Dimensional Microwave Holographic Imaging Employing Forward-Scattered Waves Only

2013 ◽  
Vol 2013 ◽  
pp. 1-15 ◽  
Author(s):  
Reza K. Amineh ◽  
Maryam Ravan ◽  
Justin McCombe ◽  
Natalia K. Nikolova
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Imaging Method ◽  
Two Dimensional ◽  
Signal To Noise ◽  
High Loss ◽  
Holographic Imaging ◽  
Multiple Receivers ◽  
Satisfactory Performance ◽  
Resolution Limits

We propose a three-dimensional microwave holographic imaging method based on the forward-scattered waves only. In the proposed method, one transmitter and multiple receivers perform together a two-dimensional scan on two planar apertures on opposite sides of the inspected domain. The ability to achieve three-dimensional imaging without back-scattered waves enables the imaging of high-loss objects, for example, tissues, where the back-scattered waves may not be available due to low signal-to-noise ratio or nonreciprocal measurement setup. The simulation and experimental results demonstrate the satisfactory performance of the proposed method in providing three-dimensional images. Resolution limits are derived and confirmed with simulation examples.

Sign in / Sign up

Export Citation Format

Share Document