Add CompositeGeometryManager

This handles FP and BP operations on multiple data objects at once,
splitting them to fit in GPU memory where necessary.

8 files changed, 1351 insertions, 14 deletions

diff --git a/src/CompositeGeometryManager.cpp b/src/CompositeGeometryManager.cpp
new file mode 100644
index 0000000..fc8bc2e
--- /dev/null
+++ b/src/CompositeGeometryManager.cpp
@@ -0,0 +1,884 @@
+/*
+-----------------------------------------------------------------------
+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/>.
+
+-----------------------------------------------------------------------
+*/
+
+#include "astra/CompositeGeometryManager.h"
+
+#ifdef ASTRA_CUDA
+
+#include "astra/GeometryUtil3D.h"
+#include "astra/VolumeGeometry3D.h"
+#include "astra/ConeProjectionGeometry3D.h"
+#include "astra/ConeVecProjectionGeometry3D.h"
+#include "astra/ParallelProjectionGeometry3D.h"
+#include "astra/ParallelVecProjectionGeometry3D.h"
+#include "astra/Projector3D.h"
+#include "astra/CudaProjector3D.h"
+#include "astra/Float32ProjectionData3DMemory.h"
+#include "astra/Float32VolumeData3DMemory.h"
+#include "astra/Logging.h"
+
+#include "../cuda/3d/mem3d.h"
+
+#include <cstring>
+
+namespace astra {
+
+// JOB:
+//  
+// VolumePart
+// ProjectionPart
+// FP-or-BP
+// SET-or-ADD
+
+
+// Running a set of jobs:
+//
+// [ Assume OUTPUT Parts in a single JobSet don't alias?? ]
+// Group jobs by output Part
+// One thread per group?
+
+// Automatically split parts if too large
+// Performance model for odd-sized tasks?
+// Automatically split parts if not enough tasks to fill available GPUs
+
+
+// Splitting:
+// Constraints:
+//   number of sub-parts divisible by N
+//   max size of sub-parts
+
+// For splitting on both input and output side:
+//   How to divide up memory? (Optimization problem; compute/benchmark)
+//   (First approach: 0.5/0.5)
+
+
+
+bool CCompositeGeometryManager::splitJobs(TJobSet &jobs, size_t maxSize, int div, TJobSet &split)
+{
+	split.clear();
+
+	for (TJobSet::const_iterator i = jobs.begin(); i != jobs.end(); ++i)
+	{
+		CPart* pOutput = i->first;
+		const TJobList &L = i->second;
+
+		// 1. Split output part
+		// 2. Per sub-part:
+		//    a. reduce input part
+		//    b. split input part
+		//    c. create jobs for new (input,output) subparts
+
+		TPartList splitOutput = pOutput->split(maxSize/3, div);
+
+		for (TJobList::const_iterator j = L.begin(); j != L.end(); ++j)
+		{
+			const SJob &job = *j;
+
+			for (TPartList::iterator i_out = splitOutput.begin();
+			     i_out != splitOutput.end(); ++i_out)
+			{
+				boost::shared_ptr<CPart> outputPart = *i_out;
+				split[outputPart.get()] = TJobList();
+
+				SJob newjob;
+				newjob.pOutput = outputPart;
+				newjob.eType = j->eType;
+				newjob.eMode = j->eMode;
+				newjob.pProjector = j->pProjector;
+
+				CPart* input = job.pInput->reduce(outputPart.get());
+
+				if (input->getSize() == 0) {
+					ASTRA_DEBUG("Empty input");
+					newjob.eType = SJob::JOB_NOP;
+					split[outputPart.get()].push_back(newjob);
+					continue;
+				}
+
+				size_t remainingSize = ( maxSize - outputPart->getSize() ) / 2;
+
+				TPartList splitInput = input->split(remainingSize, 1);
+				delete input;
+				ASTRA_DEBUG("Input split into %d parts", splitInput.size());
+
+				for (TPartList::iterator i_in = splitInput.begin();
+				     i_in != splitInput.end(); ++i_in)
+				{
+					newjob.pInput = *i_in;
+
+					split[outputPart.get()].push_back(newjob);
+
+					// Second and later (input) parts should always be added to
+					// output of first (input) part.
+					newjob.eMode = SJob::MODE_ADD;
+				}
+
+			
+			}
+
+		}
+	}
+
+	return true;
+}
+
+CCompositeGeometryManager::CPart::CPart(const CPart& other)
+{
+	eType = other.eType;
+	pData = other.pData;
+	subX = other.subX;
+	subY = other.subY;
+	subZ = other.subZ;
+}
+
+CCompositeGeometryManager::CVolumePart::CVolumePart(const CVolumePart& other)
+ : CPart(other)
+{
+	pGeom = other.pGeom->clone();
+}
+
+CCompositeGeometryManager::CVolumePart::~CVolumePart()
+{
+	delete pGeom;
+}
+
+void CCompositeGeometryManager::CVolumePart::getDims(size_t &x, size_t &y, size_t &z)
+{
+	if (!pGeom) {
+		x = y = z = 0;
+		return;
+	}
+
+	x = pGeom->getGridColCount();
+	y = pGeom->getGridRowCount();
+	z = pGeom->getGridSliceCount();
+}
+
+size_t CCompositeGeometryManager::CPart::getSize()
+{
+	size_t x, y, z;
+	getDims(x, y, z);
+	return x * y * z;
+}
+
+
+
+CCompositeGeometryManager::CPart* CCompositeGeometryManager::CVolumePart::reduce(const CPart *_other)
+{
+	const CProjectionPart *other = dynamic_cast<const CProjectionPart *>(_other);
+	assert(other);
+
+	// TODO: Is 0.5 sufficient?
+	double umin = -0.5;
+	double umax = other->pGeom->getDetectorColCount() + 0.5;
+	double vmin = -0.5;
+	double vmax = other->pGeom->getDetectorRowCount() + 0.5;
+
+	double uu[4];
+	double vv[4];
+	uu[0] = umin; vv[0] = vmin;
+	uu[1] = umin; vv[1] = vmax;
+	uu[2] = umax; vv[2] = vmin;
+	uu[3] = umax; vv[3] = vmax;
+
+	double pixx = pGeom->getPixelLengthX();
+	double pixy = pGeom->getPixelLengthY();
+	double pixz = pGeom->getPixelLengthZ();
+
+	double xmin = pGeom->getWindowMinX() - 0.5 * pixx;
+	double xmax = pGeom->getWindowMaxX() + 0.5 * pixx;
+	double ymin = pGeom->getWindowMinY() - 0.5 * pixy;
+	double ymax = pGeom->getWindowMaxY() + 0.5 * pixy;
+
+	// NB: Flipped
+	double zmax = pGeom->getWindowMinZ() - 2.5 * pixz;
+	double zmin = pGeom->getWindowMaxZ() + 2.5 * pixz;
+
+	// TODO: This isn't as tight as it could be.
+	// In particular it won't detect the detector being
+	// missed entirely on the u side.
+
+	for (int i = 0; i < other->pGeom->getProjectionCount(); ++i) {
+		for (int j = 0; j < 4; ++j) {
+			double px, py, pz;
+
+			other->pGeom->backprojectPointX(i, uu[j], vv[j], xmin, py, pz);
+			//ASTRA_DEBUG("%f %f (%f - %f)", py, pz, ymin, ymax);
+			if (pz < zmin) zmin = pz;
+			if (pz > zmax) zmax = pz;
+			other->pGeom->backprojectPointX(i, uu[j], vv[j], xmax, py, pz);
+			//ASTRA_DEBUG("%f %f (%f - %f)", py, pz, ymin, ymax);
+			if (pz < zmin) zmin = pz;
+			if (pz > zmax) zmax = pz;
+
+			other->pGeom->backprojectPointY(i, uu[j], vv[j], ymin, px, pz);
+			//ASTRA_DEBUG("%f %f (%f - %f)", px, pz, xmin, xmax);
+			if (pz < zmin) zmin = pz;
+			if (pz > zmax) zmax = pz;
+			other->pGeom->backprojectPointY(i, uu[j], vv[j], ymax, px, pz);
+			//ASTRA_DEBUG("%f %f (%f - %f)", px, pz, xmin, xmax);
+			if (pz < zmin) zmin = pz;
+			if (pz > zmax) zmax = pz;
+		}
+	}
+
+	//ASTRA_DEBUG("coord extent: %f - %f", zmin, zmax);
+
+	zmin = (zmin - pixz - pGeom->getWindowMinZ()) / pixz;
+	zmax = (zmax + pixz - pGeom->getWindowMinZ()) / pixz;
+
+	int _zmin = (int)floor(zmin);
+	int _zmax = (int)ceil(zmax);
+
+	//ASTRA_DEBUG("index extent: %d - %d", _zmin, _zmax);
+
+	if (_zmin < 0)
+		_zmin = 0;
+	if (_zmax > pGeom->getGridSliceCount())
+		_zmax = pGeom->getGridSliceCount();
+
+	if (_zmax <= _zmin) {
+		_zmin = _zmax = 0;
+	}
+	//ASTRA_DEBUG("adjusted extent: %d - %d", _zmin, _zmax);
+
+	CVolumePart *sub = new CVolumePart();
+	sub->subX = this->subX;
+	sub->subY = this->subY;
+	sub->subZ = this->subZ + _zmin;
+	sub->pData = pData;
+
+	if (_zmin == _zmax) {
+		sub->pGeom = 0;
+	} else {
+		sub->pGeom = new CVolumeGeometry3D(pGeom->getGridColCount(),
+		                                   pGeom->getGridRowCount(),
+		                                   _zmax - _zmin,
+		                                   pGeom->getWindowMinX(),
+		                                   pGeom->getWindowMinY(),
+		                                   pGeom->getWindowMinZ() + _zmin * pixz,
+		                                   pGeom->getWindowMaxX(),
+		                                   pGeom->getWindowMaxY(),
+		                                   pGeom->getWindowMinZ() + _zmax * pixz);
+	}
+
+	ASTRA_DEBUG("Reduce volume from %d - %d to %d - %d", this->subZ, this->subZ +  pGeom->getGridSliceCount(), this->subZ + _zmin, this->subZ + _zmax);
+
+	return sub;
+}
+
+
+
+static size_t ceildiv(size_t a, size_t b) {
+    return (a + b - 1) / b;
+}
+
+static size_t computeVerticalSplit(size_t maxBlock, int div, size_t sliceCount)
+{
+    size_t blockSize = maxBlock;
+    size_t blockCount = ceildiv(sliceCount, blockSize);
+
+    // Increase number of blocks to be divisible by div
+    size_t divCount = div * ceildiv(blockCount, div);
+
+    // If divCount is above sqrt(number of slices), then
+    // we can't guarantee divisibility by div, but let's try anyway
+    if (ceildiv(sliceCount, ceildiv(sliceCount, divCount)) % div == 0) {
+        blockCount = divCount;
+    } else {
+        // If divisibility isn't achievable, we may want to optimize
+        // differently.
+        // TODO: Figure out how to model and optimize this.
+    }
+
+    // Final adjustment to make blocks more evenly sized
+    // (This can't make the blocks larger)
+    blockSize = ceildiv(sliceCount, blockCount); 
+
+    ASTRA_DEBUG("%ld %ld -> %ld * %ld\n", sliceCount, maxBlock, blockCount, blockSize);
+
+    assert(blockSize <= maxBlock);
+    assert((divCount * divCount > sliceCount) || (blockCount % div) == 0);
+
+    return blockSize;
+}
+
+template<class V, class P>
+static V* getProjectionVectors(const P* geom);
+
+template<>
+SConeProjection* getProjectionVectors(const CConeProjectionGeometry3D* pProjGeom)
+{
+	return genConeProjections(pProjGeom->getProjectionCount(),
+	                          pProjGeom->getDetectorColCount(),
+	                          pProjGeom->getDetectorRowCount(),
+	                          pProjGeom->getOriginSourceDistance(),
+	                          pProjGeom->getOriginDetectorDistance(),
+	                          pProjGeom->getDetectorSpacingX(),
+	                          pProjGeom->getDetectorSpacingY(),
+	                          pProjGeom->getProjectionAngles());
+}
+
+template<>
+SConeProjection* getProjectionVectors(const CConeVecProjectionGeometry3D* pProjGeom)
+{
+	int nth = pProjGeom->getProjectionCount();
+
+	SConeProjection* pProjs = new SConeProjection[nth];
+	for (int i = 0; i < nth; ++i)
+		pProjs[i] = pProjGeom->getProjectionVectors()[i];
+
+	return pProjs;
+}
+
+template<>
+SPar3DProjection* getProjectionVectors(const CParallelProjectionGeometry3D* pProjGeom)
+{
+	return genPar3DProjections(pProjGeom->getProjectionCount(),
+	                           pProjGeom->getDetectorColCount(),
+	                           pProjGeom->getDetectorRowCount(),
+	                           pProjGeom->getDetectorSpacingX(),
+	                           pProjGeom->getDetectorSpacingY(),
+	                           pProjGeom->getProjectionAngles());
+}
+
+template<>
+SPar3DProjection* getProjectionVectors(const CParallelVecProjectionGeometry3D* pProjGeom)
+{
+	int nth = pProjGeom->getProjectionCount();
+
+	SPar3DProjection* pProjs = new SPar3DProjection[nth];
+	for (int i = 0; i < nth; ++i)
+		pProjs[i] = pProjGeom->getProjectionVectors()[i];
+
+	return pProjs;
+}
+
+
+template<class V>
+static void translateProjectionVectors(V* pProjs, int count, double dv)
+{
+	for (int i = 0; i < count; ++i) {
+		pProjs[i].fDetSX += dv * pProjs[i].fDetVX;
+		pProjs[i].fDetSY += dv * pProjs[i].fDetVY;
+		pProjs[i].fDetSZ += dv * pProjs[i].fDetVZ;
+	}
+}
+
+
+
+static CProjectionGeometry3D* getSubProjectionGeometry(const CProjectionGeometry3D* pProjGeom, int v, int size)
+{
+	// First convert to vectors, then translate, then convert into new object
+
+	const CConeProjectionGeometry3D* conegeom = dynamic_cast<const CConeProjectionGeometry3D*>(pProjGeom);
+	const CParallelProjectionGeometry3D* par3dgeom = dynamic_cast<const CParallelProjectionGeometry3D*>(pProjGeom);
+	const CParallelVecProjectionGeometry3D* parvec3dgeom = dynamic_cast<const CParallelVecProjectionGeometry3D*>(pProjGeom);
+	const CConeVecProjectionGeometry3D* conevec3dgeom = dynamic_cast<const CConeVecProjectionGeometry3D*>(pProjGeom);
+
+	if (conegeom || conevec3dgeom) {
+		SConeProjection* pConeProjs;
+		if (conegeom) {
+			pConeProjs = getProjectionVectors<SConeProjection>(conegeom);
+		} else {
+			pConeProjs = getProjectionVectors<SConeProjection>(conevec3dgeom);
+		}
+
+		translateProjectionVectors(pConeProjs, pProjGeom->getProjectionCount(), v);
+
+		CProjectionGeometry3D* ret = new CConeVecProjectionGeometry3D(pProjGeom->getProjectionCount(),
+		                                                              size,
+		                                                              pProjGeom->getDetectorColCount(),
+		                                                              pConeProjs);
+
+
+		delete[] pConeProjs;
+		return ret;
+	} else {
+		assert(par3dgeom || parvec3dgeom);
+		SPar3DProjection* pParProjs;
+		if (par3dgeom) {
+			pParProjs = getProjectionVectors<SPar3DProjection>(par3dgeom);
+		} else {
+			pParProjs = getProjectionVectors<SPar3DProjection>(parvec3dgeom);
+		}
+
+		translateProjectionVectors(pParProjs, pProjGeom->getProjectionCount(), v);
+
+		CProjectionGeometry3D* ret = new CParallelVecProjectionGeometry3D(pProjGeom->getProjectionCount(),
+		                                                                  size,
+		                                                                  pProjGeom->getDetectorColCount(),
+		                                                                  pParProjs);
+
+		delete[] pParProjs;
+		return ret;
+	}
+
+}
+
+
+
+// split self into sub-parts:
+// - each no bigger than maxSize
+// - number of sub-parts is divisible by div
+// - maybe all approximately the same size?
+CCompositeGeometryManager::TPartList CCompositeGeometryManager::CVolumePart::split(size_t maxSize, int div)
+{
+	TPartList ret;
+
+	if (true) {
+		// Split in vertical direction only at first, until we figure out
+		// a model for splitting in other directions
+
+		size_t sliceSize = ((size_t) pGeom->getGridColCount()) * pGeom->getGridRowCount();
+		int sliceCount = pGeom->getGridSliceCount();
+		size_t blockSize = computeVerticalSplit(maxSize / sliceSize, div, sliceCount);
+
+		int rem = sliceCount % blockSize;
+
+		ASTRA_DEBUG("From %d to %d step %d", -(rem / 2), sliceCount, blockSize);
+
+		for (int z = -(rem / 2); z < sliceCount; z += blockSize) {
+			int newsubZ = z;
+			if (newsubZ < 0) newsubZ = 0;
+			int endZ = z + blockSize;
+			if (endZ > sliceCount) endZ = sliceCount;
+			int size = endZ - newsubZ;
+
+			CVolumePart *sub = new CVolumePart();
+			sub->subX = this->subX;
+			sub->subY = this->subY;
+			sub->subZ = this->subZ + newsubZ;
+
+			ASTRA_DEBUG("VolumePart split %d %d %d -> %p", sub->subX, sub->subY, sub->subZ, (void*)sub);
+
+			double shift = pGeom->getPixelLengthZ() * newsubZ;
+
+			sub->pData = pData;
+			sub->pGeom = new CVolumeGeometry3D(pGeom->getGridColCount(),
+			                                   pGeom->getGridRowCount(),
+			                                   size,
+			                                   pGeom->getWindowMinX(),
+			                                   pGeom->getWindowMinY(),
+			                                   pGeom->getWindowMinZ() + shift,
+			                                   pGeom->getWindowMaxX(),
+			                                   pGeom->getWindowMaxY(),
+			                                   pGeom->getWindowMinZ() + shift + size * pGeom->getPixelLengthZ());
+
+			ret.push_back(boost::shared_ptr<CPart>(sub));
+		}
+	}
+
+	return ret;
+}
+
+CCompositeGeometryManager::CVolumePart* CCompositeGeometryManager::CVolumePart::clone() const
+{
+	return new CVolumePart(*this);
+}
+
+CCompositeGeometryManager::CProjectionPart::CProjectionPart(const CProjectionPart& other)
+ : CPart(other)
+{
+	pGeom = other.pGeom->clone();
+}
+
+CCompositeGeometryManager::CProjectionPart::~CProjectionPart()
+{
+	delete pGeom;
+}
+
+void CCompositeGeometryManager::CProjectionPart::getDims(size_t &x, size_t &y, size_t &z)
+{
+	if (!pGeom) {
+		x = y = z = 0;
+		return;
+	}
+
+	x = pGeom->getDetectorColCount();
+	y = pGeom->getProjectionCount();
+	z = pGeom->getDetectorRowCount();
+}
+
+
+CCompositeGeometryManager::CPart* CCompositeGeometryManager::CProjectionPart::reduce(const CPart *_other)
+{
+	const CVolumePart *other = dynamic_cast<const CVolumePart *>(_other);
+	assert(other);
+
+	double vmin_g, vmax_g;
+
+	// reduce self to only cover intersection with projection of VolumePart
+	// (Project corners of volume, take bounding box)
+
+	for (int i = 0; i < pGeom->getProjectionCount(); ++i) {
+
+		double vol_u[8];
+		double vol_v[8];
+
+		double pixx = other->pGeom->getPixelLengthX();
+		double pixy = other->pGeom->getPixelLengthY();
+		double pixz = other->pGeom->getPixelLengthZ();
+
+		// TODO: Is 0.5 sufficient?
+		double xmin = other->pGeom->getWindowMinX() - 0.5 * pixx;
+		double xmax = other->pGeom->getWindowMaxX() + 0.5 * pixx;
+		double ymin = other->pGeom->getWindowMinY() - 0.5 * pixy;
+		double ymax = other->pGeom->getWindowMaxY() + 0.5 * pixy;
+		double zmin = other->pGeom->getWindowMinZ() - 0.5 * pixz;
+		double zmax = other->pGeom->getWindowMaxZ() + 0.5 * pixz;
+
+		pGeom->projectPoint(xmin, ymin, zmin, i, vol_u[0], vol_v[0]);
+		pGeom->projectPoint(xmin, ymin, zmax, i, vol_u[1], vol_v[1]);
+		pGeom->projectPoint(xmin, ymax, zmin, i, vol_u[2], vol_v[2]);
+		pGeom->projectPoint(xmin, ymax, zmax, i, vol_u[3], vol_v[3]);
+		pGeom->projectPoint(xmax, ymin, zmin, i, vol_u[4], vol_v[4]);
+		pGeom->projectPoint(xmax, ymin, zmax, i, vol_u[5], vol_v[5]);
+		pGeom->projectPoint(xmax, ymax, zmin, i, vol_u[6], vol_v[6]);
+		pGeom->projectPoint(xmax, ymax, zmax, i, vol_u[7], vol_v[7]);
+
+		double vmin = vol_v[0];
+		double vmax = vol_v[0];
+
+		for (int j = 1; j < 8; ++j) {
+			if (vol_v[j] < vmin)
+				vmin = vol_v[j];
+			if (vol_v[j] > vmax)
+				vmax = vol_v[j];
+		}
+
+		if (i == 0 || vmin < vmin_g)
+			vmin_g = vmin;
+		if (i == 0 || vmax > vmax_g)
+			vmax_g = vmax;
+	}
+
+	// fprintf(stderr, "v extent: %f %f\n", vmin_g, vmax_g);
+
+	int _vmin = (int)floor(vmin_g - 1.0f);
+	int _vmax = (int)ceil(vmax_g + 1.0f);
+	if (_vmin < 0)
+		_vmin = 0;
+	if (_vmax > pGeom->getDetectorRowCount())
+		_vmax = pGeom->getDetectorRowCount();
+
+	if (_vmin >= _vmax) {
+		_vmin = _vmax = 0;
+	}
+
+	CProjectionPart *sub = new CProjectionPart();
+	sub->subX = this->subX;
+	sub->subY = this->subY;
+	sub->subZ = this->subZ + _vmin;
+
+	sub->pData = pData;
+
+	if (_vmin == _vmax) {
+		sub->pGeom = 0;
+	} else {
+		sub->pGeom = getSubProjectionGeometry(pGeom, _vmin, _vmax - _vmin);
+	}
+
+	ASTRA_DEBUG("Reduce projection from %d - %d to %d - %d", this->subZ, this->subZ + pGeom->getDetectorRowCount(), this->subZ + _vmin, this->subZ + _vmax);
+
+	return sub;
+}
+
+
+CCompositeGeometryManager::TPartList CCompositeGeometryManager::CProjectionPart::split(size_t maxSize, int div)
+{
+	TPartList ret;
+
+	if (true) {
+		// Split in vertical direction only at first, until we figure out
+		// a model for splitting in other directions
+
+		size_t sliceSize = ((size_t) pGeom->getDetectorColCount()) * pGeom->getProjectionCount();
+		int sliceCount = pGeom->getDetectorRowCount();
+		size_t blockSize = computeVerticalSplit(maxSize / sliceSize, div, sliceCount);
+
+		int rem = sliceCount % blockSize;
+
+		for (int z = -(rem / 2); z < sliceCount; z += blockSize) {
+			int newsubZ = z;
+			if (newsubZ < 0) newsubZ = 0;
+			int endZ = z + blockSize;
+			if (endZ > sliceCount) endZ = sliceCount;
+			int size = endZ - newsubZ;
+
+			CProjectionPart *sub = new CProjectionPart();
+			sub->subX = this->subX;
+			sub->subY = this->subY;
+			sub->subZ = this->subZ + newsubZ;
+
+			ASTRA_DEBUG("ProjectionPart split %d %d %d -> %p", sub->subX, sub->subY, sub->subZ, (void*)sub);
+
+			sub->pData = pData;
+
+			sub->pGeom = getSubProjectionGeometry(pGeom, newsubZ, size);
+
+			ret.push_back(boost::shared_ptr<CPart>(sub));
+		}
+	}
+
+	return ret;
+
+}
+
+CCompositeGeometryManager::CProjectionPart* CCompositeGeometryManager::CProjectionPart::clone() const
+{
+	return new CProjectionPart(*this);
+}
+
+
+bool CCompositeGeometryManager::doFP(CProjector3D *pProjector, CFloat32VolumeData3DMemory *pVolData,
+                                     CFloat32ProjectionData3DMemory *pProjData)
+{
+	ASTRA_DEBUG("CCompositeGeometryManager::doFP");
+	// Create single job for FP
+	// Run result
+
+	CVolumePart *input = new CVolumePart();
+	input->pData = pVolData;
+	input->subX = 0;
+	input->subY = 0;
+	input->subZ = 0;
+	input->pGeom = pVolData->getGeometry()->clone();
+	ASTRA_DEBUG("Main FP VolumePart -> %p", (void*)input);
+
+	CProjectionPart *output = new CProjectionPart();
+	output->pData = pProjData;
+	output->subX = 0;
+	output->subY = 0;
+	output->subZ = 0;
+	output->pGeom = pProjData->getGeometry()->clone();
+	ASTRA_DEBUG("Main FP ProjectionPart -> %p", (void*)output);
+
+	SJob FP;
+	FP.pInput = boost::shared_ptr<CPart>(input);
+	FP.pOutput = boost::shared_ptr<CPart>(output);
+	FP.pProjector = pProjector;
+	FP.eType = SJob::JOB_FP;
+	FP.eMode = SJob::MODE_SET;
+
+	TJobList L;
+	L.push_back(FP);
+
+	return doJobs(L);
+}
+
+bool CCompositeGeometryManager::doBP(CProjector3D *pProjector, CFloat32VolumeData3DMemory *pVolData,
+                                     CFloat32ProjectionData3DMemory *pProjData)
+{
+	ASTRA_DEBUG("CCompositeGeometryManager::doBP");
+	// Create single job for BP
+	// Run result
+
+	CProjectionPart *input = new CProjectionPart();
+	input->pData = pProjData;
+	input->subX = 0;
+	input->subY = 0;
+	input->subZ = 0;
+	input->pGeom = pProjData->getGeometry()->clone();
+
+	CVolumePart *output = new CVolumePart();
+	output->pData = pVolData;
+	output->subX = 0;
+	output->subY = 0;
+	output->subZ = 0;
+	output->pGeom = pVolData->getGeometry()->clone();
+
+	SJob BP;
+	BP.pInput = boost::shared_ptr<CPart>(input);
+	BP.pOutput = boost::shared_ptr<CPart>(output);
+	BP.pProjector = pProjector;
+	BP.eType = SJob::JOB_BP;
+	BP.eMode = SJob::MODE_SET;
+
+	TJobList L;
+	L.push_back(BP);
+
+	return doJobs(L);
+}
+
+
+
+bool CCompositeGeometryManager::doJobs(TJobList &jobs)
+{
+	ASTRA_DEBUG("CCompositeGeometryManager::doJobs");
+
+	// Sort job list into job set by output part
+	TJobSet jobset;
+
+	for (TJobList::iterator i = jobs.begin(); i != jobs.end(); ++i) {
+		jobset[i->pOutput.get()].push_back(*i);
+	}
+
+	size_t maxSize = astraCUDA3d::availableGPUMemory();
+	if (maxSize == 0) {
+		ASTRA_WARN("Unable to get available GPU memory. Defaulting to 1GB.");
+		maxSize = 1024 * 1024 * 1024;
+	} else {
+		ASTRA_DEBUG("Detected %lu bytes of GPU memory", maxSize);
+	}
+	maxSize = (maxSize * 9) / 10;
+
+	maxSize /= sizeof(float);
+	int div = 1;
+
+	// TODO: Multi-GPU support
+
+	// Split jobs to fit
+	TJobSet split;
+	splitJobs(jobset, maxSize, div, split);
+	jobset.clear();
+
+	// Run jobs
+	
+	for (TJobSet::iterator iter = split.begin(); iter != split.end(); ++iter) {
+
+		CPart* output = iter->first;
+		TJobList& L = iter->second;
+
+		assert(!L.empty());
+
+		bool zero = L.begin()->eMode == SJob::MODE_SET;
+
+		size_t outx, outy, outz;
+		output->getDims(outx, outy, outz);
+
+		if (L.begin()->eType == SJob::JOB_NOP) {
+			// just zero output?
+			if (zero) {
+				for (size_t z = 0; z < outz; ++z) {
+					for (size_t y = 0; y < outy; ++y) {
+						float* ptr = output->pData->getData();
+						ptr += (z + output->subX) * (size_t)output->pData->getHeight() * (size_t)output->pData->getWidth();
+						ptr += (y + output->subY) * (size_t)output->pData->getWidth();
+						ptr += output->subX;
+						memset(ptr, 0, sizeof(float) * outx);
+					}
+				}
+			}
+			continue;
+		}
+
+
+		astraCUDA3d::SSubDimensions3D dstdims;
+		dstdims.nx = output->pData->getWidth();
+		dstdims.pitch = dstdims.nx;
+		dstdims.ny = output->pData->getHeight();
+		dstdims.nz = output->pData->getDepth();
+		dstdims.subnx = outx;
+		dstdims.subny = outy;
+		dstdims.subnz = outz;
+		ASTRA_DEBUG("dstdims: %d,%d,%d in %d,%d,%d", dstdims.subnx, dstdims.subny, dstdims.subnz, dstdims.nx, dstdims.ny, dstdims.nz);
+		dstdims.subx = output->subX;
+		dstdims.suby = output->subY;
+		dstdims.subz = output->subZ;
+		float *dst = output->pData->getData();
+
+		astraCUDA3d::MemHandle3D outputMem = astraCUDA3d::allocateGPUMemory(outx, outy, outz, zero ? astraCUDA3d::INIT_ZERO : astraCUDA3d::INIT_NO);
+		bool ok = outputMem;
+
+		for (TJobList::iterator i = L.begin(); i != L.end(); ++i) {
+			SJob &j = *i;
+
+			assert(j.pInput);
+
+			CCudaProjector3D *projector = dynamic_cast<CCudaProjector3D*>(j.pProjector);
+			Cuda3DProjectionKernel projKernel = ker3d_default;
+			int detectorSuperSampling = 1;
+			int voxelSuperSampling = 1;
+			if (projector) {
+				projKernel = projector->getProjectionKernel();
+				detectorSuperSampling = projector->getDetectorSuperSampling();
+				voxelSuperSampling = projector->getVoxelSuperSampling();
+			}
+
+			size_t inx, iny, inz;
+			j.pInput->getDims(inx, iny, inz);
+			astraCUDA3d::MemHandle3D inputMem = astraCUDA3d::allocateGPUMemory(inx, iny, inz, astraCUDA3d::INIT_NO);
+
+			astraCUDA3d::SSubDimensions3D srcdims;
+			srcdims.nx = j.pInput->pData->getWidth();
+			srcdims.pitch = srcdims.nx;
+			srcdims.ny = j.pInput->pData->getHeight();
+			srcdims.nz = j.pInput->pData->getDepth();
+			srcdims.subnx = inx;
+			srcdims.subny = iny;
+			srcdims.subnz = inz;
+			srcdims.subx = j.pInput->subX;
+			srcdims.suby = j.pInput->subY;
+			srcdims.subz = j.pInput->subZ;
+			const float *src = j.pInput->pData->getDataConst();
+
+			ok = astraCUDA3d::copyToGPUMemory(src, inputMem, srcdims);
+			if (!ok) ASTRA_ERROR("Error copying input data to GPU");
+
+			if (j.eType == SJob::JOB_FP) {
+				assert(dynamic_cast<CVolumePart*>(j.pInput.get()));
+				assert(dynamic_cast<CProjectionPart*>(j.pOutput.get()));
+
+				ASTRA_DEBUG("CCompositeGeometryManager::doJobs: doing FP");
+
+				ok = astraCUDA3d::FP(((CProjectionPart*)j.pOutput.get())->pGeom, outputMem, ((CVolumePart*)j.pInput.get())->pGeom, inputMem, detectorSuperSampling, projKernel);
+				if (!ok) ASTRA_ERROR("Error performing sub-FP");
+				ASTRA_DEBUG("CCompositeGeometryManager::doJobs: FP done");
+			} else if (j.eType == SJob::JOB_BP) {
+				assert(dynamic_cast<CVolumePart*>(j.pOutput.get()));
+				assert(dynamic_cast<CProjectionPart*>(j.pInput.get()));
+
+				ASTRA_DEBUG("CCompositeGeometryManager::doJobs: doing BP");
+
+				ok = astraCUDA3d::BP(((CProjectionPart*)j.pInput.get())->pGeom, inputMem, ((CVolumePart*)j.pOutput.get())->pGeom, outputMem, voxelSuperSampling);
+				if (!ok) ASTRA_ERROR("Error performing sub-BP");
+				ASTRA_DEBUG("CCompositeGeometryManager::doJobs: BP done");
+			} else {
+				assert(false);
+			}
+
+			ok = astraCUDA3d::freeGPUMemory(inputMem);
+			if (!ok) ASTRA_ERROR("Error freeing GPU memory");
+
+		}
+
+		ok = astraCUDA3d::copyFromGPUMemory(dst, outputMem, dstdims);
+		if (!ok) ASTRA_ERROR("Error copying output data from GPU");
+		
+		ok = astraCUDA3d::freeGPUMemory(outputMem);
+		if (!ok) ASTRA_ERROR("Error freeing GPU memory");
+	}
+
+	return true;
+}
+
+
+
+}
+
+#endif
diff --git a/src/ConeProjectionGeometry3D.cpp b/src/ConeProjectionGeometry3D.cpp
index dd22eba..18f0f8a 100644
--- a/src/ConeProjectionGeometry3D.cpp
+++ b/src/ConeProjectionGeometry3D.cpp
@@ -29,6 +29,7 @@ $Id$
 #include "astra/ConeProjectionGeometry3D.h"
 
 #include "astra/Logging.h"
+#include "astra/GeometryUtil3D.h"
 
 #include <boost/lexical_cast.hpp>
 #include <cstring>
@@ -230,14 +231,14 @@ CVector3D CConeProjectionGeometry3D::getProjectionDirection(int _iProjectionInde
 	return ret;
 }
 
-void CConeProjectionGeometry3D::projectPoint(float32 fX, float32 fY, float32 fZ,
-                                                 int iAngleIndex,
-                                                 float32 &fU, float32 &fV) const
+void CConeProjectionGeometry3D::projectPoint(double fX, double fY, double fZ,
+                                             int iAngleIndex,
+                                             double &fU, double &fV) const
 {
 	ASTRA_ASSERT(iAngleIndex >= 0);
 	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
 
-	float alpha = m_pfProjectionAngles[iAngleIndex];
+	double alpha = m_pfProjectionAngles[iAngleIndex];
 
 	// Project point onto optical axis
 
@@ -245,14 +246,14 @@ void CConeProjectionGeometry3D::projectPoint(float32 fX, float32 fY, float32 fZ,
 	// Vector source->origin is (-sin(alpha), cos(alpha))
 
 	// Distance from source, projected on optical axis
-	float fD = -sin(alpha) * fX + cos(alpha) * fY + m_fOriginSourceDistance;
+	double fD = -sin(alpha) * fX + cos(alpha) * fY + m_fOriginSourceDistance;
 
 	// Scale fZ to detector plane
 	fV = detectorOffsetYToRowIndexFloat( (fZ * (m_fOriginSourceDistance + m_fOriginDetectorDistance)) / fD );
 
 
 	// Orthogonal distance in XY-plane to optical axis
-	float fS = cos(alpha) * fX + sin(alpha) * fY;
+	double fS = cos(alpha) * fX + sin(alpha) * fY;
 
 	// Scale fS to detector plane
 	fU = detectorOffsetXToColIndexFloat( (fS * (m_fOriginSourceDistance + m_fOriginDetectorDistance)) / fD );
@@ -261,5 +262,84 @@ void CConeProjectionGeometry3D::projectPoint(float32 fX, float32 fY, float32 fZ,
 
 }
 
+void CConeProjectionGeometry3D::backprojectPointX(int iAngleIndex, double fU, double fV,
+	                               double fX, double &fY, double &fZ) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SConeProjection *projs = genConeProjections(1, m_iDetectorColCount, m_iDetectorRowCount,
+	                                           m_fOriginSourceDistance,
+	                                           m_fOriginDetectorDistance,
+	                                           m_fDetectorSpacingX, m_fDetectorSpacingY,
+	                                           &m_pfProjectionAngles[iAngleIndex]);
+
+	SConeProjection &proj = projs[0];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fX - proj.fSrcX) / (px - proj.fSrcX);
+
+	fY = proj.fSrcY + a * (py - proj.fSrcY);
+	fZ = proj.fSrcZ + a * (pz - proj.fSrcZ);
+
+	delete[] projs;
+}
+
+void CConeProjectionGeometry3D::backprojectPointY(int iAngleIndex, double fU, double fV,
+	                               double fY, double &fX, double &fZ) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SConeProjection *projs = genConeProjections(1, m_iDetectorColCount, m_iDetectorRowCount,
+	                                           m_fOriginSourceDistance,
+	                                           m_fOriginDetectorDistance,
+	                                           m_fDetectorSpacingX, m_fDetectorSpacingY,
+	                                           &m_pfProjectionAngles[iAngleIndex]);
+
+	SConeProjection &proj = projs[0];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fY - proj.fSrcY) / (py - proj.fSrcY);
+
+	fX = proj.fSrcX + a * (px - proj.fSrcX);
+	fZ = proj.fSrcZ + a * (pz - proj.fSrcZ);
+
+	delete[] projs;
+}
+
+void CConeProjectionGeometry3D::backprojectPointZ(int iAngleIndex, double fU, double fV,
+	                               double fZ, double &fX, double &fY) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SConeProjection *projs = genConeProjections(1, m_iDetectorColCount, m_iDetectorRowCount,
+	                                           m_fOriginSourceDistance,
+	                                           m_fOriginDetectorDistance,
+	                                           m_fDetectorSpacingX, m_fDetectorSpacingY,
+	                                           &m_pfProjectionAngles[iAngleIndex]);
+
+	SConeProjection &proj = projs[0];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fZ - proj.fSrcZ) / (pz - proj.fSrcZ);
+
+	fX = proj.fSrcX + a * (px - proj.fSrcX);
+	fY = proj.fSrcY + a * (py - proj.fSrcY);
+
+	delete[] projs;
+}
+
+
 
 } // end namespace astra
diff --git a/src/ConeVecProjectionGeometry3D.cpp b/src/ConeVecProjectionGeometry3D.cpp
index 47ed630..86e3bd6 100644
--- a/src/ConeVecProjectionGeometry3D.cpp
+++ b/src/ConeVecProjectionGeometry3D.cpp
@@ -241,9 +241,9 @@ CVector3D CConeVecProjectionGeometry3D::getProjectionDirection(int _iProjectionI
 	return CVector3D(p.fDetSX + (u+0.5)*p.fDetUX + (v+0.5)*p.fDetVX - p.fSrcX, p.fDetSY + (u+0.5)*p.fDetUY + (v+0.5)*p.fDetVY - p.fSrcY, p.fDetSZ + (u+0.5)*p.fDetUZ + (v+0.5)*p.fDetVZ - p.fSrcZ);
 }
 
-void CConeVecProjectionGeometry3D::projectPoint(float32 fX, float32 fY, float32 fZ,
+void CConeVecProjectionGeometry3D::projectPoint(double fX, double fY, double fZ,
                                                  int iAngleIndex,
-                                                 float32 &fU, float32 &fV) const
+                                                 double &fU, double &fV) const
 {
 	ASTRA_ASSERT(iAngleIndex >= 0);
 	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
@@ -262,6 +262,60 @@ void CConeVecProjectionGeometry3D::projectPoint(float32 fX, float32 fY, float32
 }
 
 
+void CConeVecProjectionGeometry3D::backprojectPointX(int iAngleIndex, double fU, double fV,
+	                               double fX, double &fY, double &fZ) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SConeProjection &proj = m_pProjectionAngles[iAngleIndex];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fX - proj.fSrcX) / (px - proj.fSrcX);
+
+	fY = proj.fSrcY + a * (py - proj.fSrcY);
+	fZ = proj.fSrcZ + a * (pz - proj.fSrcZ);
+}
+
+void CConeVecProjectionGeometry3D::backprojectPointY(int iAngleIndex, double fU, double fV,
+	                               double fY, double &fX, double &fZ) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SConeProjection &proj = m_pProjectionAngles[iAngleIndex];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fY - proj.fSrcY) / (py - proj.fSrcY);
+
+	fX = proj.fSrcX + a * (px - proj.fSrcX);
+	fZ = proj.fSrcZ + a * (pz - proj.fSrcZ);
+}
+
+void CConeVecProjectionGeometry3D::backprojectPointZ(int iAngleIndex, double fU, double fV,
+	                               double fZ, double &fX, double &fY) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SConeProjection &proj = m_pProjectionAngles[iAngleIndex];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fZ - proj.fSrcZ) / (pz - proj.fSrcZ);
+
+	fX = proj.fSrcX + a * (px - proj.fSrcX);
+	fY = proj.fSrcY + a * (py - proj.fSrcY);
+}
+
 //----------------------------------------------------------------------------------------
 
 bool CConeVecProjectionGeometry3D::_check()
diff --git a/src/CudaBackProjectionAlgorithm3D.cpp b/src/CudaBackProjectionAlgorithm3D.cpp
index 8cf4c3b..ce8e111 100644
--- a/src/CudaBackProjectionAlgorithm3D.cpp
+++ b/src/CudaBackProjectionAlgorithm3D.cpp
@@ -37,6 +37,7 @@ $Id$
 #include "astra/ParallelProjectionGeometry3D.h"
 #include "astra/ParallelVecProjectionGeometry3D.h"
 #include "astra/ConeVecProjectionGeometry3D.h"
+#include "astra/CompositeGeometryManager.h"
 
 #include "astra/Logging.h"
 
@@ -203,9 +204,16 @@ void CCudaBackProjectionAlgorithm3D::run(int _iNrIterations)
 		                         &volgeom, projgeom,
 		                         m_iGPUIndex, m_iVoxelSuperSampling);
 	} else {
+
+#if 1
+		CCompositeGeometryManager cgm;
+
+		cgm.doBP(m_pProjector, pReconMem, pSinoMem);
+#else
 		astraCudaBP(pReconMem->getData(), pSinoMem->getDataConst(),
 		            &volgeom, projgeom,
 		            m_iGPUIndex, m_iVoxelSuperSampling);
+#endif
 	}
 
 }
diff --git a/src/CudaForwardProjectionAlgorithm3D.cpp b/src/CudaForwardProjectionAlgorithm3D.cpp
index e57e077..209f5a5 100644
--- a/src/CudaForwardProjectionAlgorithm3D.cpp
+++ b/src/CudaForwardProjectionAlgorithm3D.cpp
@@ -40,6 +40,8 @@ $Id$
 #include "astra/ParallelVecProjectionGeometry3D.h"
 #include "astra/ConeVecProjectionGeometry3D.h"
 
+#include "astra/CompositeGeometryManager.h"
+
 #include "astra/Logging.h"
 
 #include "../cuda/3d/astra3d.h"
@@ -263,6 +265,12 @@ void CCudaForwardProjectionAlgorithm3D::run(int)
 	// check initialized
 	assert(m_bIsInitialized);
 
+#if 1
+	CCompositeGeometryManager cgm;
+
+	cgm.doFP(m_pProjector, m_pVolume, m_pProjections);
+
+#else
 	const CProjectionGeometry3D* projgeom = m_pProjections->getGeometry();
 	const CVolumeGeometry3D& volgeom = *m_pVolume->getGeometry();
 
@@ -294,6 +302,7 @@ void CCudaForwardProjectionAlgorithm3D::run(int)
 	astraCudaFP(m_pVolume->getDataConst(), m_pProjections->getData(),
 	            &volgeom, projgeom,
 	            m_iGPUIndex, m_iDetectorSuperSampling, projKernel);
+#endif
 }
 
 
diff --git a/src/GeometryUtil3D.cpp b/src/GeometryUtil3D.cpp
index 52dd5a9..c6bfd8b 100644
--- a/src/GeometryUtil3D.cpp
+++ b/src/GeometryUtil3D.cpp
@@ -28,8 +28,96 @@ $Id$
 
 #include "astra/GeometryUtil3D.h"
 
+#include <cmath>
+
 namespace astra {
 
+
+SConeProjection* genConeProjections(unsigned int iProjAngles,
+                                    unsigned int iProjU,
+                                    unsigned int iProjV,
+                                    double fOriginSourceDistance,
+                                    double fOriginDetectorDistance,
+                                    double fDetUSize,
+                                    double fDetVSize,
+                                    const float *pfAngles)
+{
+	SConeProjection base;
+	base.fSrcX = 0.0f;
+	base.fSrcY = -fOriginSourceDistance;
+	base.fSrcZ = 0.0f;
+
+	base.fDetSX = iProjU * fDetUSize * -0.5f;
+	base.fDetSY = fOriginDetectorDistance;
+	base.fDetSZ = iProjV * fDetVSize * -0.5f;
+
+	base.fDetUX = fDetUSize;
+	base.fDetUY = 0.0f;
+	base.fDetUZ = 0.0f;
+
+	base.fDetVX = 0.0f;
+	base.fDetVY = 0.0f;
+	base.fDetVZ = fDetVSize;
+
+	SConeProjection* p = new SConeProjection[iProjAngles];
+
+#define ROTATE0(name,i,alpha) do { p[i].f##name##X = base.f##name##X * cos(alpha) - base.f##name##Y * sin(alpha); p[i].f##name##Y = base.f##name##X * sin(alpha) + base.f##name##Y * cos(alpha); p[i].f##name##Z = base.f##name##Z; } while(0)
+
+	for (unsigned int i = 0; i < iProjAngles; ++i) {
+		ROTATE0(Src, i, pfAngles[i]);
+		ROTATE0(DetS, i, pfAngles[i]);
+		ROTATE0(DetU, i, pfAngles[i]);
+		ROTATE0(DetV, i, pfAngles[i]);
+	}
+
+#undef ROTATE0
+
+	return p;
+}
+
+SPar3DProjection* genPar3DProjections(unsigned int iProjAngles,
+                                      unsigned int iProjU,
+                                      unsigned int iProjV,
+                                      double fDetUSize,
+                                      double fDetVSize,
+                                      const float *pfAngles)
+{
+	SPar3DProjection base;
+	base.fRayX = 0.0f;
+	base.fRayY = 1.0f;
+	base.fRayZ = 0.0f;
+
+	base.fDetSX = iProjU * fDetUSize * -0.5f;
+	base.fDetSY = 0.0f;
+	base.fDetSZ = iProjV * fDetVSize * -0.5f;
+
+	base.fDetUX = fDetUSize;
+	base.fDetUY = 0.0f;
+	base.fDetUZ = 0.0f;
+
+	base.fDetVX = 0.0f;
+	base.fDetVY = 0.0f;
+	base.fDetVZ = fDetVSize;
+
+	SPar3DProjection* p = new SPar3DProjection[iProjAngles];
+
+#define ROTATE0(name,i,alpha) do { p[i].f##name##X = base.f##name##X * cos(alpha) - base.f##name##Y * sin(alpha); p[i].f##name##Y = base.f##name##X * sin(alpha) + base.f##name##Y * cos(alpha); p[i].f##name##Z = base.f##name##Z; } while(0)
+
+	for (unsigned int i = 0; i < iProjAngles; ++i) {
+		ROTATE0(Ray, i, pfAngles[i]);
+		ROTATE0(DetS, i, pfAngles[i]);
+		ROTATE0(DetU, i, pfAngles[i]);
+		ROTATE0(DetV, i, pfAngles[i]);
+	}
+
+#undef ROTATE0
+
+	return p;
+}
+
+
+
+
 // (See declaration in header for (mathematical) description of these functions)
 
 
@@ -72,4 +160,88 @@ void computeBP_UV_Coeffs(const SConeProjection& proj, double &fUX, double &fUY,
 }
 
 
+// TODO: Handle cases of rays parallel to coordinate planes
+
+void backprojectPointX(const SPar3DProjection& proj, double fU, double fV,
+                       double fX, double &fY, double &fZ)
+{
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fX - px) / proj.fRayX;
+
+	fY = py + a * proj.fRayY;
+	fZ = pz + a * proj.fRayZ;
+}
+
+void backprojectPointY(const SPar3DProjection& proj, double fU, double fV,
+                       double fY, double &fX, double &fZ)
+{
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fY - py) / proj.fRayY;
+
+	fX = px + a * proj.fRayX;
+	fZ = pz + a * proj.fRayZ;
+
+}
+
+void backprojectPointZ(const SPar3DProjection& proj, double fU, double fV,
+                       double fZ, double &fX, double &fY)
+{
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fZ - pz) / proj.fRayZ;
+
+	fX = px + a * proj.fRayX;
+	fY = py + a * proj.fRayY;
+}
+
+
+
+void backprojectPointX(const SConeProjection& proj, double fU, double fV,
+                       double fX, double &fY, double &fZ)
+{
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fX - proj.fSrcX) / (px - proj.fSrcX);
+
+	fY = proj.fSrcY + a * (py - proj.fSrcY);
+	fZ = proj.fSrcZ + a * (pz - proj.fSrcZ);
+}
+
+void backprojectPointY(const SConeProjection& proj, double fU, double fV,
+                       double fY, double &fX, double &fZ)
+{
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fY - proj.fSrcY) / (py - proj.fSrcY);
+
+	fX = proj.fSrcX + a * (px - proj.fSrcX);
+	fZ = proj.fSrcZ + a * (pz - proj.fSrcZ);
+}
+
+void backprojectPointZ(const SConeProjection& proj, double fU, double fV,
+                       double fZ, double &fX, double &fY)
+{
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fZ - proj.fSrcZ) / (pz - proj.fSrcZ);
+
+	fX = proj.fSrcX + a * (px - proj.fSrcX);
+	fY = proj.fSrcY + a * (py - proj.fSrcY);
+}
+
+
 }
diff --git a/src/ParallelProjectionGeometry3D.cpp b/src/ParallelProjectionGeometry3D.cpp
index 1c87157..7b64fd9 100644
--- a/src/ParallelProjectionGeometry3D.cpp
+++ b/src/ParallelProjectionGeometry3D.cpp
@@ -27,8 +27,10 @@ $Id$
 */
 
 #include "astra/ParallelProjectionGeometry3D.h"
-#include <boost/lexical_cast.hpp>
 
+#include "astra/GeometryUtil3D.h"
+
+#include <boost/lexical_cast.hpp>
 #include <cstring>
 
 using namespace std;
@@ -185,9 +187,9 @@ CVector3D CParallelProjectionGeometry3D::getProjectionDirection(int _iProjection
 	return CVector3D(fDirX, fDirY, fDirZ);
 }
 
-void CParallelProjectionGeometry3D::projectPoint(float32 fX, float32 fY, float32 fZ,
+void CParallelProjectionGeometry3D::projectPoint(double fX, double fY, double fZ,
                                                  int iAngleIndex,
-                                                 float32 &fU, float32 &fV) const
+                                                 double &fU, double &fV) const
 {
 	ASTRA_ASSERT(iAngleIndex >= 0);
 	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
@@ -214,6 +216,79 @@ CParallelProjectionGeometry2D * CParallelProjectionGeometry3D::createProjectionG
 	return pOutput;
 }
 
+void CParallelProjectionGeometry3D::backprojectPointX(int iAngleIndex, double fU, double fV,
+	                               double fX, double &fY, double &fZ) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SPar3DProjection *projs = genPar3DProjections(1, m_iDetectorColCount, m_iDetectorRowCount,
+	                                           m_fDetectorSpacingX, m_fDetectorSpacingY,
+	                                           &m_pfProjectionAngles[iAngleIndex]);
+
+	SPar3DProjection &proj = projs[0];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fX - px) / proj.fRayX;
+
+	fY = py + a * proj.fRayY;
+	fZ = pz + a * proj.fRayZ;
+
+	delete[] projs;
+}
+
+void CParallelProjectionGeometry3D::backprojectPointY(int iAngleIndex, double fU, double fV,
+	                               double fY, double &fX, double &fZ) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SPar3DProjection *projs = genPar3DProjections(1, m_iDetectorColCount, m_iDetectorRowCount,
+	                                           m_fDetectorSpacingX, m_fDetectorSpacingY,
+	                                           &m_pfProjectionAngles[iAngleIndex]);
+
+	SPar3DProjection &proj = projs[0];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fY - py) / proj.fRayY;
+
+	fX = px + a * proj.fRayX;
+	fZ = pz + a * proj.fRayZ;
+
+	delete[] projs;
+}
+
+void CParallelProjectionGeometry3D::backprojectPointZ(int iAngleIndex, double fU, double fV,
+	                               double fZ, double &fX, double &fY) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SPar3DProjection *projs = genPar3DProjections(1, m_iDetectorColCount, m_iDetectorRowCount,
+	                                           m_fDetectorSpacingX, m_fDetectorSpacingY,
+	                                           &m_pfProjectionAngles[iAngleIndex]);
+
+	SPar3DProjection &proj = projs[0];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fZ - pz) / proj.fRayZ;
+
+	fX = px + a * proj.fRayX;
+	fY = py + a * proj.fRayY;
+
+	delete[] projs;
+}
+
+
 //----------------------------------------------------------------------------------------
 
 } // end namespace astra
diff --git a/src/ParallelVecProjectionGeometry3D.cpp b/src/ParallelVecProjectionGeometry3D.cpp
index ffad6d0..d04400b 100644
--- a/src/ParallelVecProjectionGeometry3D.cpp
+++ b/src/ParallelVecProjectionGeometry3D.cpp
@@ -239,9 +239,9 @@ CVector3D CParallelVecProjectionGeometry3D::getProjectionDirection(int _iProject
 	return CVector3D(p.fRayX, p.fRayY, p.fRayZ);
 }
 
-void CParallelVecProjectionGeometry3D::projectPoint(float32 fX, float32 fY, float32 fZ,
-                                                 int iAngleIndex,
-                                                 float32 &fU, float32 &fV) const
+void CParallelVecProjectionGeometry3D::projectPoint(double fX, double fY, double fZ,
+                                                    int iAngleIndex,
+                                                    double &fU, double &fV) const
 {
 	ASTRA_ASSERT(iAngleIndex >= 0);
 	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
@@ -258,6 +258,61 @@ void CParallelVecProjectionGeometry3D::projectPoint(float32 fX, float32 fY, floa
 
 }
 
+void CParallelVecProjectionGeometry3D::backprojectPointX(int iAngleIndex, double fU, double fV,
+	                               double fX, double &fY, double &fZ) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SPar3DProjection &proj = m_pProjectionAngles[iAngleIndex];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fX - px) / proj.fRayX;
+
+	fY = py + a * proj.fRayY;
+	fZ = pz + a * proj.fRayZ;
+}
+
+void CParallelVecProjectionGeometry3D::backprojectPointY(int iAngleIndex, double fU, double fV,
+	                               double fY, double &fX, double &fZ) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SPar3DProjection &proj = m_pProjectionAngles[iAngleIndex];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fY - py) / proj.fRayY;
+
+	fX = px + a * proj.fRayX;
+	fZ = pz + a * proj.fRayZ;
+}
+
+void CParallelVecProjectionGeometry3D::backprojectPointZ(int iAngleIndex, double fU, double fV,
+	                               double fZ, double &fX, double &fY) const
+{
+	ASTRA_ASSERT(iAngleIndex >= 0);
+	ASTRA_ASSERT(iAngleIndex < m_iProjectionAngleCount);
+
+	SPar3DProjection &proj = m_pProjectionAngles[iAngleIndex];
+
+	double px = proj.fDetSX + fU * proj.fDetUX + fV * proj.fDetVX;
+	double py = proj.fDetSY + fU * proj.fDetUY + fV * proj.fDetVY;
+	double pz = proj.fDetSZ + fU * proj.fDetUZ + fV * proj.fDetVZ;
+
+	double a = (fZ - pz) / proj.fRayZ;
+
+	fX = px + a * proj.fRayX;
+	fY = py + a * proj.fRayY;
+}
+
+
 //----------------------------------------------------------------------------------------
 
 bool CParallelVecProjectionGeometry3D::_check()