1 files changed, 157 insertions, 98 deletions

diff --git a/include/astra/ParallelBeamLinearKernelProjector2D.inl b/include/astra/ParallelBeamLinearKernelProjector2D.inl
index 5dd4781..61e4973 100644
--- a/include/astra/ParallelBeamLinearKernelProjector2D.inl
+++ b/include/astra/ParallelBeamLinearKernelProjector2D.inl
@@ -25,12 +25,13 @@ along with the ASTRA Toolbox. If not, see <http://www.gnu.org/licenses/>.
 -----------------------------------------------------------------------
 */
 
+#define policy_weight(p,rayindex,volindex,weight) do { if (p.pixelPrior(volindex)) { p.addWeight(rayindex, volindex, weight); p.pixelPosterior(volindex); } } while (false)
 
 template <typename Policy>
 void CParallelBeamLinearKernelProjector2D::project(Policy& p)
 {
 	projectBlock_internal(0, m_pProjectionGeometry->getProjectionAngleCount(),
-	                      0, m_pProjectionGeometry->getDetectorCount(), p);
+		                  0, m_pProjectionGeometry->getDetectorCount(), p);
 }
 
 template <typename Policy>
@@ -47,45 +48,127 @@ void CParallelBeamLinearKernelProjector2D::projectSingleRay(int _iProjection, in
 	                      _iDetector, _iDetector + 1, p);
 }
 
+
+
 //----------------------------------------------------------------------------------------
-// PROJECT BLOCK
+/* 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
+  
+   The projection kernel is defined by
+  
+                  LengthPerRow
+         /|\
+        / | \
+     __/  |  \__ 0
+       p0 p1 p2
+  
+   And thus
+      W_(rayIndex,volIndex) = (1 - offset) * lengthPerRow
+      W_(rayIndex,volIndex+1) = offset * lengthPerRow
+  
+  
+   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
+      LengthPerCol = pixelLengthY * sqrt(Rx^2+Ry^2) / |Rx|
+  
+      W_(rayIndex,volIndex) = (1 - offset) * lengthPerCol
+      W_(rayIndex,volIndex+colcount) = offset * lengthPerCol
+*/
 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;
-	float32 lengthPerCol, updatePerCol;
-	bool switch_t;
-	int iAngle, iDetector, iVolumeIndex, iRayIndex;
-	int row, col, x1;
-	float32 P,x,x2;
+	// 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 / pixelLengthX;
+	const float32 inv_pixelLengthY = 1.0f / pixelLengthY;
+	const int colCount = m_pVolumeGeometry->getGridColCount();
+	const int rowCount = m_pVolumeGeometry->getGridRowCount();
 
 	// 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;
+	for (int iAngle = _iProjFrom; iAngle < _iProjTo; ++iAngle) {
+
+		// variables
+		float32 Dx, Dy, Ex, Ey, c, r, deltac, deltar, offset;
+		float32 RxOverRy, RyOverRx, lengthPerRow, lengthPerCol;
+		int iVolumeIndex, iRayIndex, row, col, iDetector;
+
+		const SParProjection * proj = &pVecProjectionGeometry->getProjectionVectors()[iAngle];
+
+		float32 detSize = sqrt(proj->fDetUX * proj->fDetUX + proj->fDetUY * proj->fDetUY);
+
+		bool vertical = fabs(proj->fRayX) < fabs(proj->fRayY);
+		if (vertical) {
+			RxOverRy = proj->fRayX/proj->fRayY;
+			lengthPerRow = detSize * m_pVolumeGeometry->getPixelLengthX() * sqrt(proj->fRayY*proj->fRayY + proj->fRayX*proj->fRayX) / abs(proj->fRayY);
+			deltac = -pixelLengthY * RxOverRy * inv_pixelLengthX;
+		} else {
+			RyOverRx = proj->fRayY/proj->fRayX;
+			lengthPerCol = detSize * m_pVolumeGeometry->getPixelLengthY() * sqrt(proj->fRayY*proj->fRayY + proj->fRayX*proj->fRayX) / abs(proj->fRayX);
+			deltar = -pixelLengthX * RyOverRx * inv_pixelLengthY;
 		}
 
-		// 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;
-
-		// precalculate kernel limits
-		lengthPerCol = m_pVolumeGeometry->getPixelLengthX() * inv_sin_theta;
-		updatePerCol = cos_theta * inv_sin_theta;
+		Ex = m_pVolumeGeometry->getWindowMinX() + pixelLengthX*0.5f;
+		Ey = m_pVolumeGeometry->getWindowMaxY() - pixelLengthY*0.5f;
 
 		// loop detectors
 		for (iDetector = _iDetFrom; iDetector < _iDetTo; ++iDetector) {
@@ -95,79 +178,54 @@ void CParallelBeamLinearKernelProjector2D::projectBlock_internal(int _iProjFrom,
 			// POLICY: RAY PRIOR
 			if (!p.rayPrior(iRayIndex)) continue;
 	
-			// get t
-			t = m_pProjectionGeometry->indexToDetectorOffset(iDetector);
-			if (switch_t) {
-				t = -t;
-			}
+			Dx = proj->fDetSX + (iDetector+0.5f) * proj->fDetUX;
+			Dy = proj->fDetSY + (iDetector+0.5f) * proj->fDetUY;
+
+			bool isin = false;
 
 			// 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;
+			if (vertical) {
+
+				// calculate c for row 0
+				c = (Dx + (Ey - Dy)*RxOverRy - Ex) * inv_pixelLengthX;
 
-				// for each row
-				for (row = 0; row < m_pVolumeGeometry->getGridRowCount(); ++row) {
+				// loop rows
+				for (row = 0; row < rowCount; ++row, c += deltac) {
+
+					col = int(floor(c));
+					if (col < -1 || col >= colCount) { if (!isin) continue; else break; }
+					offset = c - float32(col);
+
+					iVolumeIndex = row * colCount + col;
+					if (col >= 0) { policy_weight(p, iRayIndex, iVolumeIndex, (1.0f - offset) * lengthPerRow); }
 					
-					// 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);
-						}
-					}
+					iVolumeIndex++;
+					if (col + 1 < colCount) { policy_weight(p, iRayIndex, iVolumeIndex, offset * lengthPerRow); }
+
+					isin = true;
 				}
 			}
 
 			// 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);
-						}
-					}
+			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 = int(floor(r));
+					if (row < -1 || row >= rowCount) { if (!isin) continue; else break; }
+					offset = r - float32(row);
+
+					iVolumeIndex = row * colCount + col;
+					if (row >= 0) { policy_weight(p, iRayIndex, iVolumeIndex, (1.0f - offset) * lengthPerCol); }
+
+					iVolumeIndex += colCount;
+					if (row + 1 < rowCount) { policy_weight(p, iRayIndex, iVolumeIndex, offset * lengthPerCol); }
+					
+					isin = true;
 				}
 			}
 	
@@ -177,5 +235,6 @@ void CParallelBeamLinearKernelProjector2D::projectBlock_internal(int _iProjFrom,
 		} // end loop detector
 	} // end loop angles
 
+	if (dynamic_cast<CParallelProjectionGeometry2D*>(m_pProjectionGeometry))
+		delete pVecProjectionGeometry;
 }
-