From f591df5ff62deb8de2956cc8200db4034fb6ea05 Mon Sep 17 00:00:00 2001
From: Willem Jan Palenstijn <Willem.Jan.Palenstijn@cwi.nl>
Date: Tue, 14 Feb 2017 14:10:08 +0100
Subject: Fix FDK shortscan weighting
It was computing weights for angles in [0,2pi) but using them
on angles in (-2pi,0].
---
cuda/3d/fdk.cu | 21 +++++++--------------
1 file changed, 7 insertions(+), 14 deletions(-)
diff --git a/cuda/3d/fdk.cu b/cuda/3d/fdk.cu
index bf41b62..27357ad 100644
--- a/cuda/3d/fdk.cu
+++ b/cuda/3d/fdk.cu
@@ -121,14 +121,8 @@ __global__ void devFDK_ParkerWeight(void* D_projData, unsigned int projPitch, un
// TODO: Detector pixel size
const float fU = (detectorU - 0.5f*dims.iProjU + 0.5f) * fDetUSize;
- //const float fGamma = atanf(fU / fCentralRayLength);
- //const float fBeta = gC_angle[angle];
const float fGamma = atanf(fU / fCentralRayLength);
- float fBeta = -gC_angle[angle];
- if (fBeta < 0.0f)
- fBeta += 2*M_PI;
- if (fBeta >= 2*M_PI)
- fBeta -= 2*M_PI;
+ float fBeta = gC_angle[angle];
// compute the weight depending on the location in the central fan's radon
// space
@@ -195,24 +189,23 @@ bool FDK_PreWeight(cudaPitchedPtr D_projData,
float fAngleBase;
if (fdA >= 0.0f) {
// going up from angles[0]
- fAngleBase = angles[dims.iProjAngles - 1];
+ fAngleBase = angles[0];
} else {
// going down from angles[0]
- fAngleBase = angles[0];
+ fAngleBase = angles[dims.iProjAngles - 1];
}
- // We pick the highest end of the range, and then
- // move all angles so they fall in (-2pi,0]
+ // We pick the lowest end of the range, and then
+ // move all angles so they fall in [0,2pi)
float *fRelAngles = new float[dims.iProjAngles];
for (unsigned int i = 0; i < dims.iProjAngles; ++i) {
float f = angles[i] - fAngleBase;
- while (f > 0)
+ while (f >= 2*M_PI)
f -= 2*M_PI;
- while (f <= -2*M_PI)
+ while (f < 0)
f += 2*M_PI;
fRelAngles[i] = f;
-
}
cudaError_t e1 = cudaMemcpyToSymbol(gC_angle, fRelAngles,
--
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