From 84da1d5e27abadf28e97695e88494c58bf1c2697 Mon Sep 17 00:00:00 2001
From: Willem Jan Palenstijn <Willem.Jan.Palenstijn@cwi.nl>
Date: Tue, 9 Jan 2018 14:09:23 +0100
Subject: Add sample script using parallel_vec

---
 samples/python/s022_fbp_cor.py | 98 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 samples/python/s022_fbp_cor.py

(limited to 'samples/python')

diff --git a/samples/python/s022_fbp_cor.py b/samples/python/s022_fbp_cor.py
new file mode 100644
index 0000000..eb2f56b
--- /dev/null
+++ b/samples/python/s022_fbp_cor.py
@@ -0,0 +1,98 @@
+# -----------------------------------------------------------------------
+# Copyright: 2010-2016, iMinds-Vision Lab, University of Antwerp
+#            2013-2016, CWI, Amsterdam
+#
+# Contact: astra@uantwerpen.be
+# Website: http://www.astra-toolbox.com/
+#
+# This file is part of the ASTRA Toolbox.
+#
+#
+# The ASTRA Toolbox is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# The ASTRA Toolbox is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with the ASTRA Toolbox. If not, see <http://www.gnu.org/licenses/>.
+#
+# -----------------------------------------------------------------------
+
+import astra
+import numpy as np
+
+cor_shift = 3.6
+
+vol_geom = astra.create_vol_geom(256, 256)
+proj_geom = astra.create_proj_geom('parallel', 1.0, 256, np.linspace(0,np.pi,180,False))
+
+# Projection geometry with shifted center of rotation
+# We create this by shifting the detector center V[:,2:4] by a multiple of the detector
+# orientation V[:,4:6].
+proj_geom_cor = astra.functions.geom_2vec(proj_geom)
+V = proj_geom_cor['Vectors']
+V[:,2:4] = V[:,2:4] + cor_shift * V[:,4:6]
+
+# As before, create a sinogram from a phantom, using the shifted center of rotation
+import scipy.io
+P = scipy.io.loadmat('phantom.mat')['phantom256']
+
+proj_id_cor = astra.create_projector('cuda',proj_geom_cor,vol_geom)
+sinogram_id, sinogram = astra.create_sino(P, proj_id_cor)
+
+# Change the projection geometry metadata attached to the sinogram to standard geometry,
+# and try to do a reconstruction, to show the misalignment artifacts caused by
+# the shifted center of rotation
+astra.data2d.change_geometry(sinogram_id, proj_geom)
+
+import pylab
+pylab.gray()
+pylab.figure(1)
+pylab.imshow(P)
+pylab.figure(2)
+pylab.imshow(sinogram)
+
+# Create a data object for the reconstruction
+rec_id = astra.data2d.create('-vol', vol_geom)
+
+# Set up the parameters for a reconstruction algorithm using the GPU
+cfg = astra.astra_dict('FBP_CUDA')
+cfg['ReconstructionDataId'] = rec_id
+cfg['ProjectionDataId'] = sinogram_id
+alg_id = astra.algorithm.create(cfg)
+astra.algorithm.run(alg_id)
+
+# Get the result
+rec = astra.data2d.get(rec_id)
+pylab.figure(3)
+pylab.imshow(rec)
+
+astra.algorithm.delete(alg_id)
+astra.data2d.delete(rec_id)
+
+# Now change back to the proper, shifted geometry, and do another reconstruction
+astra.data2d.change_geometry(sinogram_id, proj_geom_cor)
+rec_id = astra.data2d.create('-vol', vol_geom)
+cfg = astra.astra_dict('FBP_CUDA')
+cfg['ReconstructionDataId'] = rec_id
+cfg['ProjectionDataId'] = sinogram_id
+alg_id = astra.algorithm.create(cfg)
+astra.algorithm.run(alg_id)
+
+# Get the result
+rec = astra.data2d.get(rec_id)
+pylab.figure(4)
+pylab.imshow(rec)
+pylab.show()
+
+
+
+astra.data2d.delete(sinogram_id)
+astra.projector.delete(proj_id_cor)
+astra.algorithm.delete(alg_id)
+astra.data2d.delete(rec_id)
-- 
cgit v1.2.3