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EIDORS: Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software

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GREIT Reconstruction Examples

This tutorial shows how EIDORS gives access to the GREIT v1.0 reconstruction matrix. (The v1.0 matrix is for circular tanks defined in the 2009 publication).

Simulate 3D object

% Simulate obj $Id: GREIT_examples01.m 2775 2011-07-14 17:21:55Z aadler $

fmdl = ng_mk_cyl_models([2,1,0.1],[16,1],[0.05]); 
fmdl.stimulation = mk_stim_patterns(16,1,[0,1],[0,1],{},1);

% Homogeneous object
imgh= mk_image( fmdl, 1 );
% Fwd Simulation
vh = fwd_solve( imgh);

% Target Object
select_fcn = inline('(x-0.2).^2 + (y-0.5).^2 + (z-1).^2<0.1^2','x','y','z');
memb_frac = elem_select( imgh.fwd_model, select_fcn);
imgt= mk_image( fmdl, 1 + memb_frac );
% Fwd Simulation
vt = fwd_solve( imgt);

% Add SNR 2.0 noise
vn = add_noise(4, vt, vh);

clf; show_fem(imgt);
print_convert GREIT_examples01a.png


Figure: Simulation Mesh and object

Reconstruct (no noise)

% Simulate obj $Id: GREIT_examples02.m 4839 2015-03-30 07:44:50Z aadler $

% GREIT v1
i_gr = mk_common_gridmdl('GREITc1');

show_fem( inv_solve( i_gr, vh, vt) ); axis equal;
print_convert 'GREIT_examples02a.png' '-density 50'; 

% current GREIT recommendation
opt.noise_figure = 0.5;
opt.distr = 0; % best for cylinders
i_grc = mk_GREIT_model(fmdl,.2,[],opt);
show_fem( inv_solve( i_grc, vh, vt) ); axis equal;
print_convert 'GREIT_examples02b.png' '-density 50'; 

% Sheffield Backprojection
i_bp = mk_common_gridmdl('backproj');

show_fem( inv_solve( i_bp, vh, vt) ); axis equal;
print_convert 'GREIT_examples02c.png' '-density 50';

% 2D Gauss Newton Inverse
i_gn = mk_common_model('d2c2',16);
i_gn.hyperparameter.value = 0.1;
i_gn.fwd_model = mdl_normalize(i_gn.fwd_model, 1);
% i_gn.RtR_prior = @prior_gaussian_HPF;

show_fem( inv_solve( i_gn, vh, vt) ); axis equal;
print_convert 'GREIT_examples02d.png' '-density 50';

% Test the Noise Figure of the GN inverse => 0.5
% i_gn.hyperparameter.tgt_data.meas_t1 = vh;
% i_gn.hyperparameter.tgt_data.meas_t2 = vt;
% calc_noise_figure(i_gn)



Figure: Reconstruction (no noise) with (from left to right) GREIT v1, current GREIT recommendations, Sheffield Backprojection, Gauss Newton Inverse

Reconstruct (added noise)

% Simulate obj $Id: GREIT_examples03.m 4823 2015-03-29 15:17:16Z bgrychtol-ipa $

% GREIT v1
show_fem( inv_solve( i_gr, vh, vn) ); axis equal;
print_convert 'GREIT_examples03a.png' '-density 50';

% current GREIT
show_fem( inv_solve( i_grc, vh, vn) ); axis equal;
print_convert 'GREIT_examples03b.png' '-density 50';

% Sheffield Backprojection
show_fem( inv_solve( i_bp, vh, vn) ); axis equal;
print_convert 'GREIT_examples03c.png' '-density 50';

% 2D Gauss Newton Inverse
show_fem( inv_solve( i_gn, vh, vn) ); axis equal;
print_convert 'GREIT_examples03d.png' '-density 50';


Figure: Reconstruction (SNR=0.5 noise) with (from left to right) GREIT v1, Current GREIT, Sheffield Backprojection, Gauss Newton Inverse

Last Modified: $Date: 2017-02-28 13:12:08 -0500 (Tue, 28 Feb 2017) $ by $Author: aadler $