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| author | Willem Jan Palenstijn <Willem.Jan.Palenstijn@cwi.nl> | 2017-05-24 11:52:05 +0200 |
|---|---|---|
| committer | Willem Jan Palenstijn <Willem.Jan.Palenstijn@cwi.nl> | 2017-12-20 17:24:54 +0100 |
| commit | 52ebf0670ae39abea04344c32a1dc054c6816a03 (patch) | |
| tree | 9a8368b1ecdd9db85e6e0f721ef298733ecc0296 | |
| parent | 324611ce98a82944def875e61cb93dd98ced9c79 (diff) | |
| download | astra-52ebf0670ae39abea04344c32a1dc054c6816a03.tar.gz astra-52ebf0670ae39abea04344c32a1dc054c6816a03.tar.bz2 astra-52ebf0670ae39abea04344c32a1dc054c6816a03.tar.xz astra-52ebf0670ae39abea04344c32a1dc054c6816a03.zip | |
Document FDK weighting slightly better
| -rw-r--r-- | cuda/3d/cone_bp.cu | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/cuda/3d/cone_bp.cu b/cuda/3d/cone_bp.cu index c3405b8..02242b0 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; |