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# -----------------------------------------------------------------------
# Copyright: 2010-2021, imec Vision Lab, University of Antwerp
# 2013-2021, CWI, Amsterdam
#
# Contact: astra@astra-toolbox.com
# 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/>.
#
# -----------------------------------------------------------------------
try:
from six.moves import range
except ImportError:
# six 1.3.0
from six.moves import xrange as range
import astra
import numpy as np
vol_geom = astra.create_vol_geom(64, 64, 64)
# There are two main 3d projection geometry types: cone beam and parallel beam.
# Each has a regular variant, and a 'vec' variant.
# The 'vec' variants are completely free in the placement of source/detector,
# while the regular variants assume circular trajectories around the z-axis.
# -------------
# Parallel beam
# -------------
# Circular
# Parameters: width of detector column, height of detector row, #rows, #columns
angles = np.linspace(0, 2*np.pi, 48, False)
proj_geom = astra.create_proj_geom('parallel3d', 1.0, 1.0, 32, 64, angles)
# Free
# We generate the same geometry as the circular one above.
vectors = np.zeros((len(angles), 12))
for i in range(len(angles)):
# ray direction
vectors[i,0] = np.sin(angles[i])
vectors[i,1] = -np.cos(angles[i])
vectors[i,2] = 0
# center of detector
vectors[i,3:6] = 0
# vector from detector pixel (0,0) to (0,1)
vectors[i,6] = np.cos(angles[i])
vectors[i,7] = np.sin(angles[i])
vectors[i,8] = 0;
# vector from detector pixel (0,0) to (1,0)
vectors[i,9] = 0
vectors[i,10] = 0
vectors[i,11] = 1
# Parameters: #rows, #columns, vectors
proj_geom = astra.create_proj_geom('parallel3d_vec', 32, 64, vectors)
# ----------
# Cone beam
# ----------
# Circular
# Parameters: width of detector column, height of detector row, #rows, #columns,
# angles, distance source-origin, distance origin-detector
angles = np.linspace(0, 2*np.pi, 48, False)
proj_geom = astra.create_proj_geom('cone', 1.0, 1.0, 32, 64, angles, 1000, 0)
# Free
vectors = np.zeros((len(angles), 12))
for i in range(len(angles)):
# source
vectors[i,0] = np.sin(angles[i]) * 1000
vectors[i,1] = -np.cos(angles[i]) * 1000
vectors[i,2] = 0
# center of detector
vectors[i,3:6] = 0
# vector from detector pixel (0,0) to (0,1)
vectors[i,6] = np.cos(angles[i])
vectors[i,7] = np.sin(angles[i])
vectors[i,8] = 0
# vector from detector pixel (0,0) to (1,0)
vectors[i,9] = 0
vectors[i,10] = 0
vectors[i,11] = 1
# Parameters: #rows, #columns, vectors
proj_geom = astra.create_proj_geom('cone_vec', 32, 64, vectors)
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