For determining source locations, four techniques are used: (1) beamforming of the ambient seismic wave field, (62) (2) mapping source distribution by backprojecting observed body waves based on travel time, known as the backprojection
method, (63) (3) modeling cross-correlation functions between pairs of stations, and (4) polarization analysis of Rayleigh waves at a station.
He devotes the final chapter to techniques of using a fast analytical filtered backprojection
algorithm to emulate an iterative reconstruction with an edge-preserving de-noising constraint.
Their method requires segmentation of the training images which can be labor-intensive and costly, and identifying the local maxima and performing backprojection
can be highly sensitive to many types of noise.
Their topics include memory hierarchy for multicore and many-core processors, the Cilk and Cilk++ programming languages, efficient Aho-Corasick string matching on emerging multicore architectures, sorting on a graphics processing unit (GPU), evaluating multicore processors and accelerators for dense numerical computations, and backprojection
algorithms for multicore and GPU architectures.
Liseno, "Fast GPU-based interpolation for SAR backprojection
," Progress In Electromagnetics Research, Vol.
Wang, "Pulsed-microwave-induced thermoacoustic tomography: Filtered backprojection
in a circular measurement configuration," Med.
Both MSCT and CBCT scanners use the filtered backprojection
method as the basis for the 3D reconstruction process, thus following identical rules.
Tomographic reconstructions can be computed by a variety of different techniques such as filtered backprojection
(FBP) (Feldkamp et al, 1984; Kak and Slaney, 1988), algebraic reconstruction techniques (ART) (Gilbert, 1972; Carazo etal, 2005), geometric tomography (Gardner, 1995) or discrete tomography (Batenburg, 2005; Herman and Kuba, 2007).
Images were reconstructed using Butterworth filtered backprojection
In the second algorithm, referred to as the approximate algorithm, the kernel is modified to rewrite the inversion as a convolution backprojection
As a second example, filtered backprojection
can be used in Step 1, and we can use a nonnegatively constrained least squares algorithm in Step 2.
The 3D images were reconstructed using a 3D version of the standard filtered backprojection