BP3D_CUDA

This is a GPU implementation of a simple backprojection algorithm for 3D data sets. It takes projection data as input, and returns the backprojection of this data.

Configuration options

Name	Description
ProjectionDataId	Projection data object ID.
ReconstructionDataId	ID of data object to store the result. The content of this data is overwritten.
option.VoxelSuperSampling	Each voxel in the volume will be subdivided by this factor along each dimension. This should only be used if voxels in the volume are larger than the detector pixels (default: 1).
option.GPUindex	The index of the GPU to use (default: 0).

Example

import astra
import matplotlib.pyplot as plt
import numpy as np

# Create geometries
N = 256
N_ANGLES = 180
det_spacing = 1.0
angles = np.linspace(0, np.pi, N_ANGLES)
proj_geom = astra.create_proj_geom('parallel3d', det_spacing, det_spacing, N, N, angles)
vol_geom = astra.create_vol_geom(N, N, N)

# Generate phantom image
phantom_id, phantom = astra.data3d.shepp_logan(vol_geom)

# Create forward projection
sinogram_id, sinogram = astra.create_sino3d_gpu(phantom_id, proj_geom, vol_geom)

# Calculate backprojection
backprojection_id = astra.data3d.create('-vol', vol_geom)
cfg = astra.astra_dict('BP3D_CUDA')
cfg['ProjectionDataId'] = sinogram_id
cfg['ReconstructionDataId'] = backprojection_id
algorithm_id = astra.algorithm.create(cfg)

astra.algorithm.run(algorithm_id)

backprojection = astra.data3d.get(backprojection_id)
plt.imshow(backprojection[N//2], cmap='gray')

# Clean up
astra.data3d.delete([sinogram_id, backprojection_id, phantom_id])
astra.algorithm.delete(algorithm_id)

%% Create phantom
N = 256;
phantom_ = repmat(phantom(N), [1, 1, N]);

%% Create geometries
det_spacing = 1.0;
N_ANGLES = 180;
angles = linspace(0, pi, N_ANGLES);
proj_geom = astra_create_proj_geom('parallel3d', det_spacing, det_spacing, N, N, angles);
vol_geom = astra_create_vol_geom(N, N, N);

%% Create forward projection
[sinogram_id, sinogram] = astra_create_sino3d_cuda(phantom_, proj_geom, vol_geom);

%% Calculate backprojection
backprojection_id = astra_mex_data3d('create', '-vol', vol_geom);
cfg = astra_struct('BP3D_CUDA');
cfg.ProjectionDataId = sinogram_id;
cfg.ReconstructionDataId = backprojection_id;
algorithm_id = astra_mex_algorithm('create', cfg);

astra_mex_algorithm('run', algorithm_id);

backprojection = astra_mex_data3d('get', backprojection_id);
imshow(backprojection(:, :, N/2), []);

%% Clean up
astra_mex_data3d('delete', sinogram_id, backprojection_id);
astra_mex_algorithm('delete', algorithm_id);