Fig. 1.
Sparse matrix construction. (a) 3D matrix of distance from the pixel to transducer element in sample units calculated for an imaging array with 128 elements, and a reconstructed image of 2000×128=256000 pixels. (b) 3D matrix of re-indexed distance to follow data output by Verasonics Vantage. (c) Standard basis vectors used for the DAS iterative calculation. (d) Matrix resulting from DAS operation on a given standard basis vector. (e) Sparse matrix values allocation following 2D representation.