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Diffstat (limited to 'include/astra/FanFlatProjectionGeometry2D.h')
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diff --git a/include/astra/FanFlatProjectionGeometry2D.h b/include/astra/FanFlatProjectionGeometry2D.h new file mode 100644 index 0000000..0e790ae --- /dev/null +++ b/include/astra/FanFlatProjectionGeometry2D.h @@ -0,0 +1,244 @@ +/* +----------------------------------------------------------------------- +Copyright 2012 iMinds-Vision Lab, University of Antwerp + +Contact: astra@ua.ac.be +Website: http://astra.ua.ac.be + + +This file is part of the +All Scale Tomographic Reconstruction Antwerp Toolbox ("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/>. + +----------------------------------------------------------------------- +$Id$ +*/ + +#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); + + /** 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 */ + |