2 files changed, 70 insertions, 1 deletions
diff --git a/samples/matlab/s014_FBP.m b/samples/matlab/s014_FBP.m
index 4d1de13..fb91a41 100644
--- a/samples/matlab/s014_FBP.m
+++ b/samples/matlab/s014_FBP.m
@@ -9,7 +9,7 @@
 % -----------------------------------------------------------------------
 
 vol_geom = astra_create_vol_geom(256, 256);
-proj_geom = astra_create_proj_geom('parallel', 1.0, 384, linspace2(0,pi,180));
+proj_geom = astra_create_proj_geom('fanflat', 1.0, 384, linspace2(0,2*pi,1800), 500, 0);
 
 % As before, create a sinogram from a phantom
 P = phantom(256);
diff --git a/samples/matlab/s022_fbp_cor.m b/samples/matlab/s022_fbp_cor.m
new file mode 100644
index 0000000..b33d5ce
--- /dev/null
+++ b/samples/matlab/s022_fbp_cor.m
@@ -0,0 +1,69 @@
+% -----------------------------------------------------------------------
+% 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);