next up previous [pdf]

Next: Interpolation using shaping regularization Up: Theory Previous: Theory

Review of nonlinear shaping regularization

Supposing $ \mathbf{m}$ is a model vector and $ \mathbf{d}$ is the data after applying a forward operator $ \mathbf{F}$ . Nonlinear shaping regularization is used for solving the following equation:

$\displaystyle \mathbf{F}[\mathbf{m}]=\mathbf{d},$ (1)

using an iterative framework:

$\displaystyle \mathbf{m}_{n+1} = \mathbf{S}[\mathbf{m}_n+\mathbf{B}[\mathbf{d}-\mathbf{F}[\mathbf{m}_n]]],$ (2)

where $ [\cdot]$ means the forward operator $ \mathbf{F}$ is not limited to linear case. $ \mathbf{S}$ is the shaping operator which shapes the model to an admissible model iteratively and $ \mathbf{B}$ is the backward operator which provides an approximate mapping from data space to model space (Fomel, 2008). Specially, when $ \mathbf{B}$ is taken as the adjoint of the $ \mathbf{F}$ (in the linear case) or the adjoint of the Frechet derivative of $ \mathbf{F}$ (in the nonlinear case), and take $ \mathbf{S}$ as an identity operator, iteration 2 becomes a famous Landweber iteration (Landweber, 1951). Iteration 2 can get converged if the spectral radius of the operator on the right hand side is less than one (Collatz, 1966).


next up previous [pdf]

Next: Interpolation using shaping regularization Up: Theory Previous: Theory

2015-11-24