High resolution laser scanner with waveform digitization for subsequent full waveform analysis

2005 ◽  
Author(s):  
Andreas Ullrich ◽  
Rainer Reichert
Keyword(s):  
High Resolution ◽  
Laser Scanner ◽  
Waveform Analysis ◽  
Full Waveform

Least‐squares inversion of in‐situ sonic Q measurements: Stability and resolution

Geophysics ◽  
2004 ◽  
Vol 69 (2) ◽  
pp. 378-385 ◽  
Author(s):  
Aristotelis Dasios ◽  
Clive McCann ◽  
Timothy Astin
Keyword(s):  
High Resolution ◽  
Least Squares ◽  
Instantaneous Frequency ◽  
Spectral Ratio ◽  
Full Waveform ◽  
Multiple Measurements ◽  
Sandstone Reservoir ◽  
Gas Bearing

We minimize the effect of noise and increase both the reliability and the resolution of attenuation estimates obtained from multireceiver full‐waveform sonics. Multiple measurements of effective attenuation were generated from full‐waveform sonic data recorded by an eight‐receiver sonic tool in a gas‐bearing sandstone reservoir using two independent techniques: the logarithmic spectral ratio (LSR) and the instantaneous frequency (IF) method. After rejecting unstable estimates [receiver separation <2 ft (0.61 m)], least‐squares inversion was used to combine the multiple estimates into high‐resolution attenuation logs. The procedure was applied to raw attenuation data obtained with both the LSR and IF methods, and the resulting logs showed that the attenuation estimates obtained for the maximum receiver separation of 3.5 ft (1.07 m) provide a smoothed approximation of the high‐resolution measurements. The approximation is better for the IF method, with the normalized crosscorrelation factor between the low‐ and high‐resolution logs being 0.90 for the IF method and 0.88 for the LSR method.

scholarly journals Velocity model building by 3D frequency-domain, full-waveform inversion of wide-aperture seismic data

Geophysics ◽  
2008 ◽  
Vol 73 (5) ◽  
pp. VE101-VE117 ◽  
Author(s):  
Hafedh Ben-Hadj-Ali ◽  
Stéphane Operto ◽  
Jean Virieux
Keyword(s):  
High Resolution ◽  
Frequency Domain ◽  
Distributed Memory ◽  
Waveform Inversion ◽  
Steepest Descent Method ◽  
Frequency Domain Method ◽  
Full Waveform Inversion ◽  
Direct Solver ◽  
Velocity Models ◽  
Full Waveform

We assessed 3D frequency-domain (FD) acoustic full-waveform inversion (FWI) data as a tool to develop high-resolution velocity models from low-frequency global-offset data. The inverse problem was posed as a classic least-squares optimization problem solved with a steepest-descent method. Inversion was applied to a few discrete frequencies, allowing management of a limited subset of the 3D data volume. The forward problem was solved with a finite-difference frequency-domain method based on a massively parallel direct solver, allowing efficient multiple-shot simulations. The inversion code was fully parallelized for distributed-memory platforms, taking advantage of a domain decomposition of the modeled wavefields performed by the direct solver. After validation on simple synthetic tests, FWI was applied to two targets (channel and thrust system) of the 3D SEG/EAGE overthrust model, corresponding to 3D domains of [Formula: see text] and [Formula: see text], respectively. The maximum inverted frequencies are 15 and [Formula: see text] for the two applications. A maximum of 30 dual-core biprocessor nodes with [Formula: see text] of shared memory per node were used for the second target. The main structures were imaged successfully at a resolution scale consistent with the inverted frequencies. Our study confirms the feasibility of 3D frequency-domain FWI of global-offset data on large distributed-memory platforms to develop high-resolution velocity models. These high-velocity models may provide accurate macromodels for wave-equation prestack depth migration.

scholarly journals Shallow water seagrass observed by high resolution full waveform bathymetric LiDAR

2014 ◽  
Author(s):  
Zhigang Pan ◽  
Juan Carlos Fernandez-Diaz ◽  
Craig L. Glennie ◽  
Michael Starek
Keyword(s):  
High Resolution ◽  
Shallow Water ◽  
Full Waveform

High-Resolution 3-D Shape Integration of Dentition and Face Measured by New Laser Scanner

2004 ◽  
Vol 23 (5) ◽  
pp. 633-638 ◽  
Author(s):  
T. Sohmura ◽  
M. Nagao ◽  
M. Sakai ◽  
K. Wakabayashi ◽  
T. Kojima ◽  
...  
Keyword(s):  
High Resolution ◽  
Laser Scanner

High range resolution laser scanner with full waveform recording

2010 ◽  
Author(s):  
Dietmar Letalick ◽  
Håkan Larsson ◽  
Gustav Tolt ◽  
Lars Allard ◽  
Erika Wollner ◽  
...  
Keyword(s):  
Laser Scanner ◽  
Range Resolution ◽  
Full Waveform ◽  
High Range

scholarly journals Spectral and spatial information from a novel dual-wavelength full-waveform terrestrial laser scanner for forest ecology

2018 ◽  
Vol 8 (2) ◽  
pp. 20170049 ◽  
Author(s):  
F. Mark Danson ◽  
Fadal Sasse ◽  
Lucy A. Schofield
Keyword(s):  
Field Experiments ◽  
Forest Ecology ◽  
Laser Scanner ◽  
Dual Wavelength ◽  
Leaf Biomass ◽  
Terrestrial Laser Scanner ◽  
Area Index ◽  
Waveform Data ◽  
Full Waveform ◽  
Wide Range

The Salford Advanced Laser Canopy Analyser (SALCA) is an experimental terrestrial laser scanner designed and built specifically to measure the structural and biophysical properties of forest canopies. SALCA is a pulsed dual-wavelength instrument with co-aligned laser beams recording backscattered energy at 1063 and 1545 nm; it records full-waveform data by sampling the backscattered energy at 1 GHz giving a range resolution of 150 mm. The finest angular sampling resolution is 1 mrad and around 9 million waveforms are recorded over a hemisphere above the tripod-mounted scanner in around 110 min. Starting in 2010, data pre-processing and calibration approaches, data analysis and information extraction methods were developed and a wide range of field experiments conducted. The overall objective is to exploit the spatial, spectral and temporal characteristics of the data to produce ecologically useful information on forest and woodland canopies including leaf area index, plant area volume density and leaf biomass, and to explore the potential for tree species identification and classification. This paper outlines the key challenges in instrument development, highlights the potential applications for providing new data for forest ecology, and describes new avenues for exploring information-rich data from the next generation of terrestrial laser scanners instruments like SALCA.

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