Merge branch 'fdk'

3 files changed, 39 insertions, 11 deletions

diff --git a/cuda/3d/cone_bp.cu b/cuda/3d/cone_bp.cu
index 3dd0c97..2d12d00 100644
--- a/cuda/3d/cone_bp.cu
+++ b/cuda/3d/cone_bp.cu
@@ -126,6 +126,9 @@ __global__ void dev_cone_BP(void* D_volData, unsigned int volPitch, int startAng
 			float fVNum = fCv.w + fX * fCv.x + fY * fCv.y + fZ * fCv.z;
 			float fDen  = fCd.w + fX * fCd.x + fY * fCd.y + fZ * fCd.z;
 
+			// fCd.w = -|| u v s || (determinant of 3x3 matrix with cols u,v,s)
+			// fDen =  || u v (x-s) ||
+
 			float fU,fV, fr;
 
 			for (int idx = 0; idx < ZSIZE; idx++)
@@ -134,9 +137,17 @@ __global__ void dev_cone_BP(void* D_volData, unsigned int volPitch, int startAng
 				fU = fUNum * fr;
 				fV = fVNum * fr;
 				float fVal = tex3D(gT_coneProjTexture, fU, fAngle, fV);
-				if (FDKWEIGHT)
+				if (FDKWEIGHT) {
+					// The correct factor here is this one:
+					// Z[idx] += (fr*fCd.w)*(fr*fCd.w)*fVal;
+					// This is the square of the inverse magnification factor
+					// from fX,fY,fZ to the detector.
+
+					// Since we are assuming we have a circular cone
+					// beam trajectory, fCd.w is constant, and we instead
+					// multiply by fCd.w*fCd.w in the FDK preweighting step.
 					Z[idx] += fr*fr*fVal;
-				else
+				} else
 					Z[idx] += fVal;
 
 				fUNum += fCu.z;
@@ -255,7 +266,11 @@ bool ConeBP_Array(cudaPitchedPtr D_volumeData,
 {
 	bindProjDataTexture(D_projArray);
 
-	float fOutputScale = params.fOutputScale * params.fVolScaleX * params.fVolScaleY * params.fVolScaleZ;
+	float fOutputScale;
+	if (params.bFDKWeighting)
+		fOutputScale = params.fOutputScale / (params.fVolScaleX * params.fVolScaleY * params.fVolScaleZ);
+	else
+		fOutputScale = params.fOutputScale * (params.fVolScaleX * params.fVolScaleY * params.fVolScaleZ);
 
 	for (unsigned int th = 0; th < dims.iProjAngles; th += g_MaxAngles) {
 		unsigned int angleCount = g_MaxAngles;
diff --git a/cuda/3d/fdk.cu b/cuda/3d/fdk.cu
index 4e926f2..48194c4 100644
--- a/cuda/3d/fdk.cu
+++ b/cuda/3d/fdk.cu
@@ -59,7 +59,7 @@ __constant__ float gC_angle[g_MaxAngles];
 // per-detector u/v shifts?
 
 
-__global__ void devFDK_preweight(void* D_projData, unsigned int projPitch, unsigned int startAngle, unsigned int endAngle, float fSrcOrigin, float fDetOrigin, float fZShift, float fDetUSize, float fDetVSize, const SDimensions3D dims)
+__global__ void devFDK_preweight(void* D_projData, unsigned int projPitch, unsigned int startAngle, unsigned int endAngle, float fSrcOrigin, float fDetOrigin, float fZShift, float fDetUSize, float fDetVSize, float fVoxSize, const SDimensions3D dims)
 {
 	float* projData = (float*)D_projData;
 	int angle = startAngle + blockIdx.y * g_anglesPerWeightBlock + threadIdx.y;
@@ -83,10 +83,18 @@ __global__ void devFDK_preweight(void* D_projData, unsigned int projPitch, unsig
 
 	float fV = (startDetectorV - 0.5f*dims.iProjV + 0.5f) * fDetVSize + fZShift;
 
-	//const float fW = fCentralRayLength;
-	//const float fW = fCentralRayLength * (M_PI / 2.0f) / (float)dims.iProjAngles;
+	// Contributions to the weighting factors:
+	// fCentralRayLength / fRayLength   : the main FDK preweighting factor
+	// fSrcOrigin / (fDetUSize * fCentralRayLength)
+	//                                  : to adjust the filter to the det width
+	// || u v s || ^ 2                  : see cone_bp.cu, FDKWEIGHT
+	// pi / (2 * iProjAngles)           : scaling of the integral over angles
+	// fVoxSize ^ 2                     : ...
+
 	const float fW1 = fSrcOrigin * fDetUSize * fDetVSize;
-	const float fW = fCentralRayLength * fW1 * fW1 * (M_PI / 2.0f) / (float)dims.iProjAngles;
+	const float fW2 = fCentralRayLength / (fDetUSize * fSrcOrigin);
+	const float fW3 = fVoxSize * fVoxSize;
+	const float fW = fCentralRayLength * fW1 * fW1 * fW2 * fW3 * (M_PI / 2.0f) / (float)dims.iProjAngles;
 
 	for (int detectorV = startDetectorV; detectorV < endDetectorV; ++detectorV)
 	{
@@ -142,6 +150,8 @@ __global__ void devFDK_ParkerWeight(void* D_projData, unsigned int projPitch, un
 		fWeight = 0.0f;
 	}
 
+	fWeight *= 2; // adjust to effectively halved angular range
+
 	for (int detectorV = startDetectorV; detectorV < endDetectorV; ++detectorV)
 	{
 
@@ -156,7 +166,8 @@ __global__ void devFDK_ParkerWeight(void* D_projData, unsigned int projPitch, un
 bool FDK_PreWeight(cudaPitchedPtr D_projData,
                 float fSrcOrigin, float fDetOrigin,
                 float fZShift,
-                float fDetUSize, float fDetVSize, bool bShortScan,
+                float fDetUSize, float fDetVSize, float fVoxSize,
+				bool bShortScan,
                 const SDimensions3D& dims, const float* angles)
 {
 	// The pre-weighting factor for a ray is the cosine of the angle between
@@ -168,7 +179,7 @@ bool FDK_PreWeight(cudaPitchedPtr D_projData,
 
 	int projPitch = D_projData.pitch/sizeof(float);
 
-	devFDK_preweight<<<dimGrid, dimBlock>>>(D_projData.ptr, projPitch, 0, dims.iProjAngles, fSrcOrigin, fDetOrigin, fZShift, fDetUSize, fDetVSize, dims);
+	devFDK_preweight<<<dimGrid, dimBlock>>>(D_projData.ptr, projPitch, 0, dims.iProjAngles, fSrcOrigin, fDetOrigin, fZShift, fDetUSize, fDetVSize, fVoxSize, dims);
 
 	cudaTextForceKernelsCompletion();
 
@@ -310,8 +321,9 @@ bool FDK(cudaPitchedPtr D_volumeData,
 
 
 #if 1
+	// NB: assuming cube voxels (params.fVolScaleX)
 	ok = FDK_PreWeight(D_projData, fSrcOrigin, fDetOrigin,
-	                fZShift, fDetUSize, fDetVSize,
+	                fZShift, fDetUSize, fDetVSize, params.fVolScaleX,
 	                bShortScan, dims, pfAngles);
 #else
 	ok = true;
diff --git a/cuda/3d/fdk.h b/cuda/3d/fdk.h
index f4049e6..6f6e73b 100644
--- a/cuda/3d/fdk.h
+++ b/cuda/3d/fdk.h
@@ -35,7 +35,8 @@ namespace astraCUDA3d {
 bool FDK_PreWeight(cudaPitchedPtr D_projData,
                 float fSrcOrigin, float fDetOrigin,
                 float fZShift,
-                float fDetUSize, float fDetVSize, bool bShortScan,
+                float fDetUSize, float fDetVSize, float fVoxSize,
+                bool bShortScan,
                 const SDimensions3D& dims, const float* angles);
 
 bool FDK(cudaPitchedPtr D_volumeData,