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EIDORS: Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software

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Strange Effect: Opposite vs Adjacent measurement/stimulation

If we stimulate and measure using an opposite protocol, then the EIT image algorithm cannot tell which part of the object the image comes from, and a mirror image is created.
%$Id: opposite_meas01.m 5310 2017-01-20 20:53:53Z aadler $
imdl= mk_common_model('c2c2',16);
imdl.fwd_model = rmfield(imdl.fwd_model,'meas_select');


% Simulate with AD / AD
imdl.fwd_model.stimulation = mk_stim_patterns(16,1,'{ad}','{ad}',{},1);
[vi,vh] = simulate_2d_movement( 5, imdl.fwd_model, [.9,.05], 2);
imgs= inv_solve(imdl, vh, vi);
imgs.show_slices.img_cols = 5; imgs.calc_colours.ref_level = 0;
subplot(411); show_slices(imgs)

% Simulate with OP / AD
imdl.fwd_model.stimulation = mk_stim_patterns(16,1,'{op}','{ad}',{},1);
[vi,vh] = simulate_2d_movement( 5, imdl.fwd_model, [.9,.05], 2);
imgs= inv_solve(imdl, vh, vi); 
imgs.show_slices.img_cols = 5; imgs.calc_colours.ref_level = 0;
subplot(412); show_slices(imgs)

% Simulate with AD / OP
imdl.fwd_model.stimulation = mk_stim_patterns(16,1,'{ad}','{op}',{},1);
[vi,vh] = simulate_2d_movement( 5, imdl.fwd_model, [.9,.05], 2);
imgs= inv_solve(imdl, vh, vi); 
imgs.show_slices.img_cols = 5; imgs.calc_colours.ref_level = 0;
subplot(413); show_slices(imgs)

% Simulate with OP / OP
imdl.fwd_model.stimulation = mk_stim_patterns(16,1,'{op}','{op}',{},1);
[vi,vh] = simulate_2d_movement( 5, imdl.fwd_model, [.9,.05], 2);
imgs= inv_solve(imdl, vh, vi); 
imgs.show_slices.img_cols = 5; imgs.calc_colours.ref_level = 0;
subplot(414); show_slices(imgs)

print_convert opposite_meas01.png


Figure: Images of a target moving from centre to the right. From Top to Bottom: Adjacent Stim / Adjacent Meas Opposite Stim / Adjacent Meas Adjacent Stim / Opposite Meas Opposite Stim / Opposite Meas

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