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/*
-----------------------------------------------------------------------
Copyright: 2010-2016, iMinds-Vision Lab, University of Antwerp
2014-2016, CWI, Amsterdam
Contact: astra@uantwerpen.be
Website: http://www.astra-toolbox.com/
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/>.
-----------------------------------------------------------------------
*/
#ifndef _INC_ASTRA_FANFLATPROJECTIONGEOMETRY2D
#define _INC_ASTRA_FANFLATPROJECTIONGEOMETRY2D
#include "ProjectionGeometry2D.h"
#include <cmath>
namespace astra
{
/**
* This class defines a 2D fan beam geometry with a flat detector that has equally spaced detector cells.
*
* \par XML Configuration
* \astra_xml_item{DetectorCount, int, Number of detectors for each projection.}
* \astra_xml_item{DetectorWidth, float, Width of each detector.}
* \astra_xml_item{ProjectionAngles, vector of float, projection angles in radians.}
* \astra_xml_item{DistanceOriginDetector, float, Distance between the center of rotation and the detectorarray.}
* \astra_xml_item{DistanceOriginSource, float, Distance between the center of rotation the the x-ray source.}
*
* \par MATLAB example
* \astra_code{
* proj_geom = astra_struct('fanflat');\n
* proj_geom.DetectorCount = 512;\n
* proj_geom.DetectorWidth = 1.0;\n
* proj_geom.ProjectionAngles = linspace(0,pi,100);\n
* proj_geom.DistanceOriginDetector = 300;\n
* proj_geom.DistanceOriginSource = 300;\n
* }
*/
class _AstraExport CFanFlatProjectionGeometry2D : public CProjectionGeometry2D
{
/**
* Distance from the origin of the coordinate system to the source.
*/
float32 m_fOriginSourceDistance;
/**
* Distance from the origin of the coordinate system to the detector (i.e., the distance between the origin and its orthogonal projection
* onto the detector array).
*/
float32 m_fOriginDetectorDistance;
public:
/** Default constructor. Sets all variables to zero. Note that this constructor leaves the object in an unusable state and must
* be followed by a call to init().
*/
CFanFlatProjectionGeometry2D();
/** Constructor.
*
* @param _iProjectionAngleCount Number of projection angles.
* @param _iDetectorCount Number of detectors, i.e., the number of detector measurements for each projection angle.
* @param _fDetectorWidth Width of a detector cell, in unit lengths. All detector cells are assumed to have equal width.
* @param _pfProjectionAngles Pointer to an array of projection angles. The angles will be copied from this array.
* All angles are represented in radians.
* @param _fOriginSourceDistance Distance from the origin of the coordinate system to the source
* @param _fOriginDetectorDistance Distance from the origin of the coordinate system to the detector
*/
CFanFlatProjectionGeometry2D(int _iProjectionAngleCount,
int _iDetectorCount,
float32 _fDetectorWidth,
const float32* _pfProjectionAngles,
float32 _fOriginSourceDistance,
float32 _fOriginDetectorDistance);
/** Copy constructor.
*/
CFanFlatProjectionGeometry2D(const CFanFlatProjectionGeometry2D& _projGeom);
/** Assignment operator.
*/
CFanFlatProjectionGeometry2D& operator=(const CFanFlatProjectionGeometry2D& _other);
/** Destructor.
*/
virtual ~CFanFlatProjectionGeometry2D();
/** Initialize the geometry with a config object.
*
* @param _cfg Configuration Object
* @return initialization successful?
*/
virtual bool initialize(const Config& _cfg);
/** Initialization. This function MUST be called after using the default constructor and MAY be called to
* reset a previously initialized object.
*
* @param _iProjectionAngleCount Number of projection angles.
* @param _iDetectorCount Number of detectors, i.e., the number of detector measurements for each projection angle.
* @param _fDetectorWidth Width of a detector cell, in unit lengths. All detector cells are assumed to have equal width.
* @param _pfProjectionAngles Pointer to an array of projection angles. The angles will be copied from this array.
* @param _fOriginSourceDistance Distance from the origin of the coordinate system to the source
* @param _fOriginDetectorDistance Distance from the origin of the coordinate system to the detector
*/
bool initialize(int _iProjectionAngleCount,
int _iDetectorCount,
float32 _fDetectorWidth,
const float32* _pfProjectionAngles,
float32 _fOriginSourceDistance,
float32 _fOriginDetectorDistance);
/** Create a hard copy.
*/
virtual CProjectionGeometry2D* clone();
/** Returns true if the type of geometry defined in this class is the one specified in _sType.
*
* @param _sType geometry type to compare to.
* @return true if _sType == "fanflat".
*/
virtual bool isOfType(const std::string& _sType);
/** Get all settings in a Config object.
*
* @return Configuration Object.
*/
virtual Config* getConfiguration() const;
/** Return true if this geometry instance is the same as the one specified.
*
* @return true if this geometry instance is the same as the one specified.
*/
virtual bool isEqual(CProjectionGeometry2D*) const;
/** Returns the distance from the origin of the coordinate system to the source.
*
* @return Distance from the origin of the coordinate system to the source
*/
float32 getOriginSourceDistance() const;
/** Returns the distance from the origin of the coordinate system to the detector
* (i.e., the distance between the origin and its orthogonal projection onto the detector array).
*
* @return Distance from the origin of the coordinate system to the detector
*/
float32 getOriginDetectorDistance() const;
/** Returns the distance from the source to the detector
* (i.e., the distance between the source and its orthogonal projection onto the detector array).
*
* @return Distance from the source to the detector
*/
float32 getSourceDetectorDistance() const;
/** Get the value for t and theta, based upon the row and column index.
*
* @param _iRow row index
* @param _iColumn column index
* @param _fT output: value of t
* @param _fTheta output: value of theta, always lies within the [0,pi[ interval.
*/
virtual void getRayParams(int _iRow, int _iColumn, float32& _fT, float32& _fTheta) const;
/**
* Returns a vector describing the direction of a ray belonging to a certain detector
*
* @param _iProjectionIndex index of projection
* @param _iProjectionIndex index of detector
*
* @return a unit vector describing the direction
*/
virtual CVector3D getProjectionDirection(int _iProjectionIndex, int _iDetectorIndex);
};
// Returns the distance from the origin of the coordinate system to the source.
inline float32 CFanFlatProjectionGeometry2D::getOriginSourceDistance() const
{
return m_fOriginSourceDistance;
}
// Returns the distance from the origin of the coordinate system to the detector.
inline float32 CFanFlatProjectionGeometry2D::getOriginDetectorDistance() const
{
return m_fOriginDetectorDistance;
}
// Returns the distance from the source to the detector.
inline float32 CFanFlatProjectionGeometry2D::getSourceDetectorDistance() const
{
return (m_fOriginSourceDistance + m_fOriginDetectorDistance);
}
// Get T and Theta
inline void CFanFlatProjectionGeometry2D::getRayParams(int _iRow, int _iColumn, float32& _fT, float32& _fTheta) const
{
assert(m_bInitialized);
// get the distance between the center of the detector array and the detector.
float32 det_offset = indexToDetectorOffset(_iColumn);
// get the angle between the center ray of the projection and the projection.
float32 alpha = atan(det_offset / getSourceDetectorDistance());
// calculate t and theta
_fT = m_fOriginSourceDistance * sin(alpha);
_fTheta = getProjectionAngle(_iRow) + alpha;
// if theta is larger than pi, flip of the origin
if (PI <= _fTheta) {
_fTheta -= PI;
_fT = -_fT;
}
// if theta is below 0, flip
if (_fTheta < 0) {
_fTheta += PI;
_fT = -_fT;
}
}
} // namespace astra
#endif /* _INC_ASTRA_FANFLATPROJECTIONGEOMETRY2D */
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