Add sample script using parallel_vec

1 files changed, 69 insertions, 0 deletions

diff --git a/samples/matlab/s022_fbp_cor.m b/samples/matlab/s022_fbp_cor.m
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+++ b/samples/matlab/s022_fbp_cor.m
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+% -----------------------------------------------------------------------
+% This file is part of the ASTRA Toolbox
+% 
+% Copyright: 2010-2016, iMinds-Vision Lab, University of Antwerp
+%            2014-2016, CWI, Amsterdam
+% License: Open Source under GPLv3
+% Contact: astra@uantwerpen.be
+% Website: http://www.astra-toolbox.com/
+% -----------------------------------------------------------------------
+
+cor_shift = 3.6;
+
+vol_geom = astra_create_vol_geom(256, 256);
+proj_geom = astra_create_proj_geom('parallel', 1.0, 256, linspace2(0,pi,180));
+
+% Projection geometry with shifted center of rotation
+% We create this by shifting the detector center V(:,3:4) by a multiple of the detector
+% orientation V(:,5:6).
+proj_geom_cor = astra_geom_2vec(proj_geom);
+proj_geom_cor.Vectors(:,3:4) = proj_geom_cor.Vectors(:,3:4) + cor_shift * proj_geom_cor.Vectors(:,5:6);
+
+% As before, create a sinogram from a phantom, using the shifted center of rotation
+P = phantom(256);
+[sinogram_id, sinogram] = astra_create_sino_gpu(P, proj_geom_cor, vol_geom);
+figure(1); imshow(P, []);
+figure(2); imshow(sinogram, []);
+
+astra_mex_data2d('delete', sinogram_id);
+
+% We now re-create the sinogram data object as we would do when loading
+% an external sinogram, using a standard geometry, and try to do a reconstruction,
+% to show the misalignment artifacts caused by the shifted center of rotation
+sinogram_id = astra_mex_data2d('create', '-sino', proj_geom, sinogram);
+
+% Create a data object for the reconstruction
+rec_id = astra_mex_data2d('create', '-vol', vol_geom);
+
+% Set up the parameters for a reconstruction algorithm using the GPU
+cfg = astra_struct('FBP_CUDA');
+cfg.ReconstructionDataId = rec_id;
+cfg.ProjectionDataId = sinogram_id;
+alg_id = astra_mex_algorithm('create', cfg);
+astra_mex_algorithm('run', alg_id);
+
+% Get the result
+rec = astra_mex_data2d('get', rec_id);
+figure(3); imshow(rec, []);
+
+astra_mex_algorithm('delete', alg_id);
+astra_mex_data2d('delete', rec_id);
+
+% Now change back to the proper, shifted geometry, and do another reconstruction
+astra_mex_data2d('change_geometry', sinogram_id, proj_geom_cor);
+rec_id = astra_mex_data2d('create', '-vol', vol_geom);
+
+cfg = astra_struct('FBP_CUDA');
+cfg.ReconstructionDataId = rec_id;
+cfg.ProjectionDataId = sinogram_id;
+alg_id = astra_mex_algorithm('create', cfg);
+astra_mex_algorithm('run', alg_id);
+
+% Get the result
+rec = astra_mex_data2d('get', rec_id);
+figure(4); imshow(rec, []);
+
+
+astra_mex_algorithm('delete', alg_id);
+astra_mex_data2d('delete', rec_id);
+astra_mex_data2d('delete', sinogram_id);