k-Wave User Forum » Topic: Problem in 3D time reversal reconsturction in planar detection geometry

k-Wave User Forum » Topic: Problem in 3D time reversal reconsturction in planar detection geometry http://www.k-wave.org/forum/topic/problem-in-3d-time-reversal-reconsturction-in-planar-detection-geometry Support for the k-Wave MATLAB toolbox en-US Wed, 13 May 2026 01:51:32 +0000 http://bbpress.org/?v=1.0.2 <![CDATA[Search]]> q http://www.k-wave.org/forum/search.php wangk524 on "Problem in 3D time reversal reconsturction in planar detection geometry" http://www.k-wave.org/forum/topic/problem-in-3d-time-reversal-reconsturction-in-planar-detection-geometry#post-7690 Sun, 05 Jul 2020 22:11:13 +0000 wangk524 7690@http://www.k-wave.org/forum/ Thank you Dr. Treeby. Bradley Treeby on "Problem in 3D time reversal reconsturction in planar detection geometry" http://www.k-wave.org/forum/topic/problem-in-3d-time-reversal-reconsturction-in-planar-detection-geometry#post-7563 Sat, 06 Jun 2020 14:50:02 +0000 Bradley Treeby 7563@http://www.k-wave.org/forum/ The simulation is unstable (a warning is printed to the command line). You need to decrease the CFL / time step. Brad. wangk524 on "Problem in 3D time reversal reconsturction in planar detection geometry" http://www.k-wave.org/forum/topic/problem-in-3d-time-reversal-reconsturction-in-planar-detection-geometry#post-7528 Wed, 27 May 2020 07:25:43 +0000 wangk524 7528@http://www.k-wave.org/forum/ Hi, I am trying to generate a basic TR reconstruction (3d) for planar geometry. Although, my problem involves reconstructing metal-tissue interface, I am at first trying to get reconstructions for homogenous domain settings. I am getting a very poor reconstruction for a data-rich problem. I do expect limited view artifacts, but this is much worse than that. Please let me know if I am doing something wrong here? How can I improve my reconstructions? Also, while carrying out reconstruction for heterogeneous case (sound speed and density can be upto 4-6 times of that of water) can I expect a good reconstruction?? Please give me insights on this aspect as well. Sincerely, Kevin The problem setting, true PA source, and reconstruction are uploaded at: <a href="https://imgur.com/a/XGRelbN" rel="nofollow">https://imgur.com/a/XGRelbN</a> %% ************ Code TR - homogeneous SOS and density ******************** % ========================================================================= % SIMULATION % ========================================================================= % % assign the grid size and create the computational grid domain_size=2e-2; PML_size = 20; % size of the PML in grid points dx =0.1e-3; % grid point spacing in the x direction [m] dy =0.1e-3; % grid point spacing in the y direction [m] dz =0.1e-3; % grid point spacing in the y direction [m] Nx = round(domain_size/dx); % number of grid points in the x direction Ny = round(domain_size/dx/5) ; %number of grid points in the y direction Nz = round(domain_size/dx); % number of grid points in the z direction kgrid = makeGrid(Nx, dx, Ny, dy, Nz, dz); p0 = zeros(Nx,Ny,Nz); medium.sound_speed = 1500*ones(Nx,Ny,Nz); %% background medium.density = 1000*ones(Nx,Ny,Nz); %% background metal_sze = 2e-3; % side length of the metal cube sz_vox = round(metal_sze/dx); tissue_sze = 1e-3; tissue_vox = tissue_sze/dx; for i = 1:Nx for j=1:Ny for k=1:Nz if abs(Nx/2-i)<= sz_vox/2 && abs(Ny/2-j)<=sz_vox/2 && abs(Nz/2-k)<=sz_vox/2 p0(i,j,k)=2; % medium.sound_speed(i,j,k)=1500; %6000; % medium.density(i,j,k)= 1000; %3000; elseif abs(Nx/2+sz_vox/2-i)<=tissue_vox && abs(Ny/2-j)<=sz_vox/2 && abs(Nz/2-k)<=sz_vox/2 p0(i,j,k)=1; % medium.sound_speed(i,j,k)=1500; %1600; % medium.density(i,j,k)= 1000; %1500; end end end end % smooth the initial pressure distribution and restore the magnitude source.p0 = smooth(kgrid, p0, true); % medium.sound_speed = smooth(kgrid, medium.sound_speed, true); % medium.density = smooth(kgrid, medium.density, true); p_slice = p0(:,:,round(Nz/2)); figure, imagesc(p_slice) % Detection setting and measurement generation :---- % define a binary planar sensor sensor.mask = zeros(kgrid.Nx, kgrid.Ny, kgrid.Nz); sensor.mask(:,1,:) = 1; %% create the time array % [kgrid.t_array, dt] = makeTime(kgrid, medium.sound_speed); dt = 1/8e6; kgrid.t_array= 0:dt:100*dt; % set the input arguements input_args = {'PMLSize', PML_size, 'PMLInside', false, ... 'PlotPML', false, 'Smooth', false, 'DataCast', 'single'}; % run the simulation tic sensor_data = kspaceFirstOrder3D(kgrid, medium, source, sensor, input_args{:}); toc % reset the initial pressure source.p0 = 0; % assign the time reversal data sensor.time_reversal_boundary_data = sensor_data; % run the time-reversal reconstruction p0_recon = kspaceFirstOrder3D(kgrid, medium, source, sensor, input_args{:}); % add first order compensation for only recording over a half plane p0_recon = 2 * p0_recon; % apply a positivity condition p0_recon(p0_recon < 0) = 0; p_rec_slice = p0_recon(:,:,round(Nz/2)); figure, imagesc(p_rec_slice)