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/*
-----------------------------------------------------------------------
Copyright 2012 iMinds-Vision Lab, University of Antwerp
Contact: astra@ua.ac.be
Website: http://astra.ua.ac.be
This file is part of the
All Scale Tomographic Reconstruction Antwerp Toolbox ("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/>.
-----------------------------------------------------------------------
$Id$
*/
template <typename Policy>
void CParallelBeamLinearKernelProjector2D::project(Policy& p)
{
projectBlock_internal(0, m_pProjectionGeometry->getProjectionAngleCount(),
0, m_pProjectionGeometry->getDetectorCount(), p);
}
template <typename Policy>
void CParallelBeamLinearKernelProjector2D::projectSingleProjection(int _iProjection, Policy& p)
{
projectBlock_internal(_iProjection, _iProjection + 1,
0, m_pProjectionGeometry->getDetectorCount(), p);
}
template <typename Policy>
void CParallelBeamLinearKernelProjector2D::projectSingleRay(int _iProjection, int _iDetector, Policy& p)
{
projectBlock_internal(_iProjection, _iProjection + 1,
_iDetector, _iDetector + 1, p);
}
//----------------------------------------------------------------------------------------
// PROJECT BLOCK
template <typename Policy>
void CParallelBeamLinearKernelProjector2D::projectBlock_internal(int _iProjFrom, int _iProjTo, int _iDetFrom, int _iDetTo, Policy& p)
{
// variables
float32 theta, sin_theta, cos_theta, inv_sin_theta, inv_cos_theta, t;
float32 lengthPerRow, updatePerRow, inv_pixelLengthX;
float32 lengthPerCol, updatePerCol, inv_pixelLengthY;
bool switch_t;
int iAngle, iDetector, iVolumeIndex, iRayIndex;
int row, col, x1;
float32 P,x,x2;
// loop angles
for (iAngle = _iProjFrom; iAngle < _iProjTo; ++iAngle) {
// get theta
theta = m_pProjectionGeometry->getProjectionAngle(iAngle);
switch_t = false;
if (theta >= 7*PIdiv4) theta -= 2*PI;
if (theta >= 3*PIdiv4) {
theta -= PI;
switch_t = true;
}
// precalculate sin, cos, 1/cos
sin_theta = sin(theta);
cos_theta = cos(theta);
inv_cos_theta = 1.0f / cos_theta;
inv_sin_theta = 1.0f / sin_theta;
// precalculate kernel limits
lengthPerRow = m_pVolumeGeometry->getPixelLengthY() * inv_cos_theta;
updatePerRow = sin_theta * inv_cos_theta;
inv_pixelLengthX = 1.0f / m_pVolumeGeometry->getPixelLengthX();
// precalculate kernel limits
lengthPerCol = m_pVolumeGeometry->getPixelLengthX() * inv_sin_theta;
updatePerCol = cos_theta * inv_sin_theta;
inv_pixelLengthY = 1.0f / m_pVolumeGeometry->getPixelLengthY();
// loop detectors
for (iDetector = _iDetFrom; iDetector < _iDetTo; ++iDetector) {
iRayIndex = iAngle * m_pProjectionGeometry->getDetectorCount() + iDetector;
// POLICY: RAY PRIOR
if (!p.rayPrior(iRayIndex)) continue;
// get t
t = m_pProjectionGeometry->indexToDetectorOffset(iDetector);
if (switch_t) {
t = -t;
}
// vertically
if (theta <= PIdiv4) {
// calculate x for row 0
P = (t - sin_theta * m_pVolumeGeometry->pixelRowToCenterY(0)) * inv_cos_theta;
x = m_pVolumeGeometry->coordXToColF(P) - 0.5f;
// for each row
for (row = 0; row < m_pVolumeGeometry->getGridRowCount(); ++row) {
// get coords
x1 = int((x > 0.0f) ? x : x-1.0f);
x2 = x - x1;
x += updatePerRow;
// add weights
if (x1 >= 0 && x1 < m_pVolumeGeometry->getGridColCount()) {
iVolumeIndex = m_pVolumeGeometry->pixelRowColToIndex(row, x1);
// POLICY: PIXEL PRIOR + ADD + POSTERIOR
if (p.pixelPrior(iVolumeIndex)) {
p.addWeight(iRayIndex, iVolumeIndex, (1.0f - x2) * lengthPerRow);
p.pixelPosterior(iVolumeIndex);
}
}
if (x1+1 >= 0 && x1+1 < m_pVolumeGeometry->getGridColCount()) {
iVolumeIndex = m_pVolumeGeometry->pixelRowColToIndex(row, x1+1);
// POLICY: PIXEL PRIOR + ADD + POSTERIOR
if (p.pixelPrior(iVolumeIndex)) {
p.addWeight(iRayIndex, iVolumeIndex, (x2) * lengthPerRow);
p.pixelPosterior(iVolumeIndex);
}
}
}
}
// horizontally
else if (PIdiv4 <= theta && theta <= 3*PIdiv4) {
// calculate point P
P = (t - cos_theta * m_pVolumeGeometry->pixelColToCenterX(0)) * inv_sin_theta;
x = m_pVolumeGeometry->coordYToRowF(P) - 0.5f;
// for each row
for (col = 0; col < m_pVolumeGeometry->getGridColCount(); ++col) {
// get coords
x1 = int((x > 0.0f) ? x : x-1.0f);
x2 = x - x1;
x += updatePerCol;
// add weights
if (x1 >= 0 && x1 < m_pVolumeGeometry->getGridRowCount()) {
iVolumeIndex = m_pVolumeGeometry->pixelRowColToIndex(x1, col);
// POLICY: PIXEL PRIOR + ADD + POSTERIOR
if (p.pixelPrior(iVolumeIndex)) {
p.addWeight(iRayIndex, iVolumeIndex, (1.0f - x2) * lengthPerCol);
p.pixelPosterior(iVolumeIndex);
}
}
if (x1+1 >= 0 && x1+1 < m_pVolumeGeometry->getGridRowCount()) {
iVolumeIndex = m_pVolumeGeometry->pixelRowColToIndex(x1+1, col);
// POLICY: PIXEL PRIOR + ADD + POSTERIOR
if (p.pixelPrior(iVolumeIndex)) {
p.addWeight(iRayIndex, iVolumeIndex, x2 * lengthPerCol);
p.pixelPosterior(iVolumeIndex);
}
}
}
}
// POLICY: RAY POSTERIOR
p.rayPosterior(iRayIndex);
} // end loop detector
} // end loop angles
}
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