summaryrefslogtreecommitdiffstats
path: root/include/astra/ParallelBeamBlobKernelProjector2D.inl
blob: c2aa1938e179bd21823a54a879f2a4eea0949393 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
/*
-----------------------------------------------------------------------
Copyright: 2010-2015, iMinds-Vision Lab, University of Antwerp
           2014-2015, CWI, Amsterdam

Contact: astra@uantwerpen.be
Website: http://sf.net/projects/astra-toolbox

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/>.

-----------------------------------------------------------------------
$Id$
*/


template <typename Policy>
void CParallelBeamBlobKernelProjector2D::project(Policy& p)
{
	projectBlock_internal(0, m_pProjectionGeometry->getProjectionAngleCount(),
						  0, m_pProjectionGeometry->getDetectorCount(), p);
}

template <typename Policy>
void CParallelBeamBlobKernelProjector2D::projectSingleProjection(int _iProjection, Policy& p)
{
	projectBlock_internal(_iProjection, _iProjection + 1,
						  0, m_pProjectionGeometry->getDetectorCount(), p);
}

template <typename Policy>
void CParallelBeamBlobKernelProjector2D::projectSingleRay(int _iProjection, int _iDetector, Policy& p)
{
	projectBlock_internal(_iProjection, _iProjection + 1,
						  _iDetector, _iDetector + 1, p);
}

//----------------------------------------------------------------------------------------
// PROJECT BLOCK - vector projection geometry
// 
// Kernel limitations: isotropic pixels (PixelLengthX == PixelLengthY)
//
// For each angle/detector pair:
// 
// Let D=(Dx,Dy) denote the centre of the detector (point) in volume coordinates, and
// let R=(Rx,Ry) denote the direction of the ray (vector).
// 
// For mainly vertical rays (|Rx|<=|Ry|), 
// let E=(Ex,Ey) denote the centre of the most upper left pixel:
//    E = (WindowMinX +  PixelLengthX/2, WindowMaxY - PixelLengthY/2),
// and let F=(Fx,Fy) denote a vector to the next pixel 
//    F = (PixelLengthX, 0)
// 
// The intersection of the ray (D+aR) with the centre line of the upper row of pixels (E+bF) is
//    { Dx + a*Rx = Ex + b*Fx
//    { Dy + a*Ry = Ey + b*Fy
// Solving for (a,b) results in:
//    a = (Ey + b*Fy - Dy)/Ry
//      = (Ey - Dy)/Ry
//    b = (Dx + a*Rx - Ex)/Fx
//      = (Dx + (Ey - Dy)*Rx/Ry - Ex)/Fx
//
// Define c as the x-value of the intersection of the ray with the upper row in pixel coordinates. 
//    c = b 
//
// The intersection of the ray (D+aR) with the centre line of the second row of pixels (E'+bF) with
//    E'=(WindowMinX + PixelLengthX/2, WindowMaxY - 3*PixelLengthY/2)
// expressed in x-value pixel coordinates is
//    c' = (Dx + (Ey' - Dy)*Rx/Ry - Ex)/Fx.
// And thus:
//    deltac = c' - c = (Dx + (Ey' - Dy)*Rx/Ry - Ex)/Fx - (Dx + (Ey - Dy)*Rx/Ry - Ex)/Fx
//                    = [(Ey' - Dy)*Rx/Ry - (Ey - Dy)*Rx/Ry]/Fx
//                    = [Ey' - Ey]*(Rx/Ry)/Fx
//                    = [Ey' - Ey]*(Rx/Ry)/Fx
//                    = -PixelLengthY*(Rx/Ry)/Fx.
// 
// Given c on a certain row, its pixel directly on its left (col), and the distance (offset) to it, can be found: 
//    col = floor(c)
//    offset = c - col
//
// The index of this pixel is
//    volumeIndex = row * colCount + col
//
//
// Mainly horizontal rays (|Rx|<=|Ry|) are handled in a similar fashion:
//
//    E = (WindowMinX +  PixelLengthX/2, WindowMaxY - PixelLengthY/2),
//    F = (0, -PixelLengthX)
//
//    a = (Ex + b*Fx - Dx)/Rx = (Ex - Dx)/Rx
//    b = (Dy + a*Ry - Ey)/Fy = (Dy + (Ex - Dx)*Ry/Rx - Ey)/Fy
//    r = b
//    deltar = PixelLengthX*(Ry/Rx)/Fy.
//    row = floor(r+1/2)
//    offset = r - row
//
template <typename Policy>
void CParallelBeamBlobKernelProjector2D::projectBlock_internal(int _iProjFrom, int _iProjTo, int _iDetFrom, int _iDetTo, Policy& p)
{
	// get vector geometry
	const CParallelVecProjectionGeometry2D* pVecProjectionGeometry;
	if (dynamic_cast<CParallelProjectionGeometry2D*>(m_pProjectionGeometry)) {
		pVecProjectionGeometry = dynamic_cast<CParallelProjectionGeometry2D*>(m_pProjectionGeometry)->toVectorGeometry();
	} else {
		pVecProjectionGeometry = dynamic_cast<CParallelVecProjectionGeometry2D*>(m_pProjectionGeometry);
	}

	// precomputations
	const float32 pixelLengthX = m_pVolumeGeometry->getPixelLengthX();
	const float32 pixelLengthY = m_pVolumeGeometry->getPixelLengthY();	
	const float32 inv_pixelLengthX = 1.0f / m_pVolumeGeometry->getPixelLengthX();
	const float32 inv_pixelLengthY = 1.0f / m_pVolumeGeometry->getPixelLengthY();
	const int colCount = m_pVolumeGeometry->getGridColCount();
	const int rowCount = m_pVolumeGeometry->getGridRowCount();
	const int detCount = pVecProjectionGeometry->getDetectorCount();

	// loop angles
	#pragma omp parallel for
	for (int iAngle = _iProjFrom; iAngle < _iProjTo; ++iAngle) {

		// variables
		float32 Dx, Dy, Ex, Ey, c, r, deltac, deltar, offset, invBlobExtent, RxOverRy, RyOverRx;
		int iVolumeIndex, iRayIndex, row, col, iDetector;
		int col_left, col_right, row_top, row_bottom, index;

		const SParProjection * proj = &pVecProjectionGeometry->getProjectionVectors()[iAngle];

		bool vertical = fabs(proj->fRayX) < fabs(proj->fRayY);
		if (vertical) {
			RxOverRy = proj->fRayX/proj->fRayY;
			deltac = -m_pVolumeGeometry->getPixelLengthY() * (proj->fRayX/proj->fRayY) * inv_pixelLengthX;
			invBlobExtent = m_pVolumeGeometry->getPixelLengthY() / abs(m_fBlobSize * sqrt(proj->fRayY*proj->fRayY + proj->fRayX*proj->fRayX) / proj->fRayY);
		} else {
			RyOverRx = proj->fRayY/proj->fRayX;
			deltar = -m_pVolumeGeometry->getPixelLengthX() * (proj->fRayY/proj->fRayX) * inv_pixelLengthY;
			invBlobExtent = m_pVolumeGeometry->getPixelLengthX() / abs(m_fBlobSize * sqrt(proj->fRayY*proj->fRayY + proj->fRayX*proj->fRayX) / proj->fRayX);
		}

		Ex = m_pVolumeGeometry->getWindowMinY() + pixelLengthX*0.5f;
		Ey = m_pVolumeGeometry->getWindowMaxY() - pixelLengthY*0.5f;

		// loop detectors
		for (iDetector = _iDetFrom; iDetector < _iDetTo; ++iDetector) {
			
			iRayIndex = iAngle * m_pProjectionGeometry->getDetectorCount() + iDetector;

			// POLICY: RAY PRIOR
			if (!p.rayPrior(iRayIndex)) continue;
	
			Dx = proj->fDetSX + (iDetector+0.5f) * proj->fDetUX;
			Dy = proj->fDetSY + (iDetector+0.5f) * proj->fDetUY;

			// vertically
			if (vertical) {

				// calculate c for row 0
				c = (Dx + (Ey - Dy)*RxOverRy - Ex) * inv_pixelLengthX;

				// loop rows
				for (row = 0; row < rowCount; ++row, c += deltac) {

					col_left = int(c - 0.5f - m_fBlobSize);
					col_right = int(c + 0.5f + m_fBlobSize);

					if (col_left < 0) col_left = 0; 
					if (col_right > colCount-1) col_right = colCount-1; 

					// loop columns
					for (col = col_left; col <= col_right; ++col) {

						iVolumeIndex = row * colCount + col;
						// POLICY: PIXEL PRIOR + ADD + POSTERIOR
						if (p.pixelPrior(iVolumeIndex)) {
							offset = abs(c - float32(col)) * invBlobExtent;
							index = (int)(offset*m_iBlobSampleCount+0.5f);
							p.addWeight(iRayIndex, iVolumeIndex, m_pfBlobValues[min(index,m_iBlobSampleCount-1)]);
							p.pixelPosterior(iVolumeIndex);
						}
					}
				}
			}

			// horizontally
			else {

				// calculate r for col 0
				r = -(Dy + (Ex - Dx)*RyOverRx - Ey) * inv_pixelLengthY;

				// loop columns
				for (col = 0; col < colCount; ++col, r += deltar) {

					row_top = int(r - 0.5f - m_fBlobSize);
					row_bottom = int(r + 0.5f + m_fBlobSize);

					if (row_top < 0) row_top = 0; 
					if (row_bottom > rowCount-1) row_bottom = rowCount-1; 

					// loop rows
					for (row = row_top; row <= row_bottom; ++row) {

						iVolumeIndex = row * colCount + col;
						// POLICY: PIXEL PRIOR + ADD + POSTERIOR
						if (p.pixelPrior(iVolumeIndex)) {
							offset = abs(r - float32(row)) * invBlobExtent;
							index = (int)(offset*m_iBlobSampleCount+0.5f);
							p.addWeight(iRayIndex, iVolumeIndex, m_pfBlobValues[min(index,m_iBlobSampleCount-1)]);
							p.pixelPosterior(iVolumeIndex);
						}
					}
				}
			}
	
			// POLICY: RAY POSTERIOR
			p.rayPosterior(iRayIndex);
	
		} // end loop detector
	} // end loop angles

}