itk::Ray< TInputImage, TCoordRep > Class Template Reference

Class to project a ray through a 3D volume. More...

Public Types
typedef itk::Point< TCoordRep, 3 >	InputPointType
typedef itk::Point< TCoordRep, 2 >	OutputPointType
typedef TInputImage	InputImageType
typedef InputImageType::PixelType	PixelType
typedef InputImageType::IndexType	IndexType
typedef InputImageType::SizeType	SizeType
typedef InputImageType::OffsetValueType	OffsetValueType
typedef itk::Matrix< double, 4, 4 >	ProjectionMatrixType

Public Member Functions
	Ray ()
	Constructor. More...
virtual	~Ray ()
	Destructor. More...
void	SetProjectionMatrix (const ProjectionMatrixType input)
	Set the combined affine and projection matrix. More...
void	SetImage (const InputImageType *input)
bool	SetRay (OutputPointType RayPosn)
void	SetProjectionResolution2Dmm (double xRes, double yRes)
double	GetCurrentIntensity (void) const
	Return the interpolated intensity of the current ray point. More...
double	GetRayPointSpacing (void) const
	Return the ray point spacing in mm. More...
int	GetNumberOfRayPoints (void)
	Return the number of points on the ray. More...
void	GetBilinearCoefficients (double &y, double &z) const
	Get the the bilinear coefficient for the current ray point. More...
PixelType **	GetRayIntersectionVoxels (void)
const int *	GetRayIntersectionVoxelIndex (void) const
	Get the voxel index of the intersection. More...
int	GetTraversalDirection (void)
	Get the traversal direction. More...
bool	Integrate (double &integral)
	Integrate the interpolated intensities along the ray and return the result. More...
bool	IntegrateAboveThreshold (double &integral, double threshold)
	Integrate the interpolated intensities above a given threshold, along the ray and return the result. More...
bool	IncrementRayVoxelIntensities (double increment)
	Increment each of the intensities of the 4 planar voxels surrounding every point along the ray using bilinear interpolation. More...
void	IncrementIntensities (double increment)
	Increment each of the intensities of the 4 planar voxels surrounding the current ray point using bilinear interpolation. More...
void	IncrementIntensities (void)
	Increment each of the intensities of the 4 planar voxels surrounding the current ray point by one. More...
void	Reset (void)
	Reset the iterator to the start of the ray. More...
bool	NextPoint (void)
	Step along the ray. More...

Protected Types
enum	TraversalDirection {   UNDEFINED_DIRECTION =0, TRANSVERSE_IN_X, TRANSVERSE_IN_Y, TRANSVERSE_IN_Z,   LAST_DIRECTION }

Protected Member Functions
void	ZeroState ()
	Set the initial zero state of the object. More...
void	Initialise (void)
	Initialise the object. More...
void	EndPointsInVoxels (void)
	Calculate the endpoint coordinats of the ray in voxels. More...
void	CalcDirnVector (void)
bool	AdjustRayLength (void)
void	InitialiseVoxelPointers (void)
void	IncrementVoxelPointers (void)
	Increment the voxel pointers surrounding the current point on the ray. More...
void	RecordVolumeDimensions (void)
	Record volume dimensions and resolution. More...
void	DefineCorners (void)
	Define the corners of the volume. More...
void	CalcPlanesAndCorners (void)
	Calculate the planes which define the volume. More...
bool	CalcRayIntercepts (void)
	Calculate the ray intercepts with the volume. More...
void	Line3D (double x2D, double y2D, double r[3], double u[3])
	Calculate the equation of the ray throught the volume. More...

Protected Attributes
const InputImageType *	m_Image
bool	m_ValidRay
	Flag indicating whether the current ray is valid. More...
double	m_RayPosition2Dmm [2]
	The ray intercept 2D coordinate. More...
double	m_ProjectionResolution2Dmm [2]
	The resolution of the 2D projection image. More...
double	m_RayVoxelStartPosition [3]
	The start position of the ray in voxels. More...
double	m_RayVoxelEndPosition [3]
	The end coordinate of the ray in voxels. More...
double	m_Position3Dvox [3]
	The current coordinate on the ray in voxels. More...
double	m_VoxelIncrement [3]
TraversalDirection	m_TraversalDirection
	The direction in which the ray is incremented thorough the volume (x, y or z). More...
int	m_TotalRayVoxelPlanes
	The total number of planes of voxels traversed by the ray. More...
int	m_NumVoxelPlanesTraversed
	The current number of planes of voxels traversed by the ray. More...
PixelType *	m_RayIntersectionVoxels [4]
	Pointers to the current four voxels surrounding the ray's trajectory. More...
int	m_RayIntersectionVoxelIndex [3]
int	m_NumberOfVoxelsInX
	The dimension in voxels of the 3D volume in along the x axis. More...
int	m_NumberOfVoxelsInY
	The dimension in voxels of the 3D volume in along the y axis. More...
int	m_NumberOfVoxelsInZ
	The dimension in voxels of the 3D volume in along the z axis. More...
double	m_VoxelDimensionInX
	Voxel dimension in x. More...
double	m_VoxelDimensionInY
	Voxel dimension in y. More...
double	m_VoxelDimensionInZ
	Voxel dimension in z. More...
double	m_RayStartCoordInMM [3]
	The coordinate of the point at which the ray enters the volume in mm. More...
double	m_RayEndCoordInMM [3]
	The coordinate of the point at which the ray exits the volume in mm. More...
double	m_BoundingPlane [6][4]
	Planes which define the boundary of the volume in mm (six planes and four parameters: Ax+By+Cz+D). More...
double	m_BoundingCorner [8][3]
	The eight corners of the volume (x,y,z coordinates for each). More...
double	m_CurrentRayPositionInMM [3]
	The position of the ray in 3D. More...
double	m_RayDirectionInMM [3]
	The direction of the ray. More...
ProjectionMatrixType	m_ProjectionMatrix
	The combined affine and perspective transformation. More...

Detailed Description

template<class TInputImage, class TCoordRep = double>
class itk::Ray< TInputImage, TCoordRep >

Class to project a ray through a 3D volume.

Member Typedef Documentation

template<class TInputImage , class TCoordRep = double>

typedef InputImageType::IndexType itk::Ray< TInputImage, TCoordRep >::IndexType

template<class TInputImage , class TCoordRep = double>

typedef TInputImage itk::Ray< TInputImage, TCoordRep >::InputImageType

template<class TInputImage , class TCoordRep = double>

typedef itk::Point<TCoordRep, 3> itk::Ray< TInputImage, TCoordRep >::InputPointType

template<class TInputImage , class TCoordRep = double>

typedef InputImageType::OffsetValueType itk::Ray< TInputImage, TCoordRep >::OffsetValueType

template<class TInputImage , class TCoordRep = double>

typedef itk::Point<TCoordRep, 2> itk::Ray< TInputImage, TCoordRep >::OutputPointType

template<class TInputImage , class TCoordRep = double>

typedef InputImageType::PixelType itk::Ray< TInputImage, TCoordRep >::PixelType

template<class TInputImage , class TCoordRep = double>

typedef itk::Matrix<double, 4, 4> itk::Ray< TInputImage, TCoordRep >::ProjectionMatrixType

The combined affine and perspective projection matrix type. NB: defined as a square matrix because ITK does not appear to support matrix multiplication of non square matrices.

template<class TInputImage , class TCoordRep = double>

typedef InputImageType::SizeType itk::Ray< TInputImage, TCoordRep >::SizeType

Member Enumeration Documentation

template<class TInputImage , class TCoordRep = double>

enum itk::Ray::TraversalDirection

protected

The ray is traversed by stepping in the axial direction that enables the greatest number of planes in the volume to be intercepted.

Enumerator
UNDEFINED_DIRECTION	Undefined.
TRANSVERSE_IN_X	x
TRANSVERSE_IN_Y	y
TRANSVERSE_IN_Z	z
LAST_DIRECTION

Constructor & Destructor Documentation

template<class TInputImage , class TCoordRep = double>

itk::Ray< TInputImage, TCoordRep >::Ray

(

)

Constructor.

template<class TInputImage , class TCoordRep = double>

virtual itk::Ray< TInputImage, TCoordRep >::~Ray ( )

inlinevirtual

Destructor.

Member Function Documentation

template<class TInputImage , class TCoordRep = double>

bool itk::Ray< TInputImage, TCoordRep >::AdjustRayLength ( void  )

protected

Reduce the length of the ray until both start and end coordinates lie inside the volume.

Returns

True if a valid ray has been, false otherwise.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::CalcDirnVector ( void  )

protected

Calculate the incremental direction vector in voxels, 'dVoxel', required to traverse the ray.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::CalcPlanesAndCorners ( void  )

protected

Calculate the planes which define the volume.

Member function to calculate the equations of the planes of 4 of the sides of the volume, calculate the positions of the 8 corners of the volume in mm in World, also calculate the values of the slopes of the lines which go to make up the volume( defined as lines in cube x,y,z dirn and then each of these lines has a slope in the world x,y,z dirn [3]) and finally also to return the length of the sides of the lines in mm.

template<class TInputImage , class TCoordRep = double>

bool itk::Ray< TInputImage, TCoordRep >::CalcRayIntercepts ( void  )

protected

Calculate the ray intercepts with the volume.

See where the ray cuts the volume, check that truncation does not occur, if not, then start ray where it first intercepts the volume and set x_max to be where it leaves the volume.

Returns

True if a valid ray has been specified, false otherwise.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::DefineCorners ( void  )

protected

Define the corners of the volume.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::EndPointsInVoxels ( void  )

protected

Calculate the endpoint coordinats of the ray in voxels.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::GetBilinearCoefficients	(	double &	y,
		double &	z
	)		const

Get the the bilinear coefficient for the current ray point.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::GetCurrentIntensity

(

void

)

const

Return the interpolated intensity of the current ray point.

template<class TInputImage , class TCoordRep = double>

int itk::Ray< TInputImage, TCoordRep >::GetNumberOfRayPoints ( void  )

inline

Return the number of points on the ray.

template<class TInputImage , class TCoordRep = double>

const int* itk::Ray< TInputImage, TCoordRep >::GetRayIntersectionVoxelIndex ( void  ) const

inline

Get the voxel index of the intersection.

template<class TInputImage , class TCoordRep = double>

PixelType** itk::Ray< TInputImage, TCoordRep >::GetRayIntersectionVoxels ( void  )

inline

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::GetRayPointSpacing ( void  ) const

inline

Return the ray point spacing in mm.

template<class TInputImage , class TCoordRep = double>

int itk::Ray< TInputImage, TCoordRep >::GetTraversalDirection ( void  )

inline

Get the traversal direction.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::IncrementIntensities

(

double

increment

)

Increment each of the intensities of the 4 planar voxels surrounding the current ray point using bilinear interpolation.

increment Intensity increment for each of the current 4 voxels

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::IncrementIntensities

(

void

)

Increment each of the intensities of the 4 planar voxels surrounding the current ray point by one.

template<class TInputImage , class TCoordRep = double>

bool itk::Ray< TInputImage, TCoordRep >::IncrementRayVoxelIntensities

(

double

increment

)

Increment each of the intensities of the 4 planar voxels surrounding every point along the ray using bilinear interpolation.

increment Intensity increment for each of the current 4 voxels

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::IncrementVoxelPointers ( void  )

protected

Increment the voxel pointers surrounding the current point on the ray.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::Initialise ( void  )

protected

Initialise the object.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::InitialiseVoxelPointers ( void  )

protected

Obtain pointers to the four voxels surrounding the point where the ray enters the volume.

template<class TInputImage , class TCoordRep = double>

bool itk::Ray< TInputImage, TCoordRep >::Integrate ( double &  integral )

inline

Integrate the interpolated intensities along the ray and return the result.

This routine can be called after instantiating the ray and calling SetProjectionCoord2D() or Reset(). It may then be called as many times thereafter for different 2D projection coordinates.

Parameters

integral

The integrated intensities along the ray.

Returns

True if a valid ray was specified.

template<class TInputImage , class TCoordRep = double>

bool itk::Ray< TInputImage, TCoordRep >::IntegrateAboveThreshold	(	double &	integral,
		double	threshold
	)

Integrate the interpolated intensities above a given threshold, along the ray and return the result.

This routine can be called after instantiating the ray and calling SetProjectionCoord2D() or Reset(). It may then be called as many times thereafter for different 2D projection coordinates.

Parameters

integral	The integrated intensities along the ray.
threshold	The integration threshold [default value: 0]

Returns

True if a valid ray was specified.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::Line3D ( double  x2D, double  y2D, double  r[3], double  u[3]  )

protected

Calculate the equation of the ray throught the volume.

template<class TInputImage , class TCoordRep = double>

bool itk::Ray< TInputImage, TCoordRep >::NextPoint

(

void

)

Step along the ray.

This routine can be called iteratively to step along a given ray. To specify a new ray call: 'SetRay()' first. To re-traverse the current ray call: 'Reset()'.

Returns

False if there are no more points on the ray.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::RecordVolumeDimensions ( void  )

protected

Record volume dimensions and resolution.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::Reset

(

void

)

Reset the iterator to the start of the ray.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::SetImage ( const InputImageType *  input )

inline

Set the image class

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::SetProjectionMatrix ( const ProjectionMatrixType  input )

inline

Set the combined affine and projection matrix.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::SetProjectionResolution2Dmm ( double  xRes, double  yRes  )

inline

Set the resolution of the 2D projection image. This is used to normalise the projected intensities to ensure the back-projected 3D image will have similar sum of intensities to the original volume.

template<class TInputImage , class TCoordRep = double>

bool itk::Ray< TInputImage, TCoordRep >::SetRay

(

OutputPointType

RayPosn

)

Initialise the ray using the position of a point on the 2D projection image

Parameters

RayPosn

The position of the ray in 2D (mm).

Returns

True if this is a valid ray.

template<class TInputImage , class TCoordRep = double>

void itk::Ray< TInputImage, TCoordRep >::ZeroState ( )

protected

Set the initial zero state of the object.

Member Data Documentation

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_BoundingCorner[8][3]

protected

The eight corners of the volume (x,y,z coordinates for each).

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_BoundingPlane[6][4]

protected

Planes which define the boundary of the volume in mm (six planes and four parameters: Ax+By+Cz+D).

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_CurrentRayPositionInMM[3]

protected

The position of the ray in 3D.

template<class TInputImage , class TCoordRep = double>

const InputImageType* itk::Ray< TInputImage, TCoordRep >::m_Image

protected

template<class TInputImage , class TCoordRep = double>

int itk::Ray< TInputImage, TCoordRep >::m_NumberOfVoxelsInX

protected

The dimension in voxels of the 3D volume in along the x axis.

template<class TInputImage , class TCoordRep = double>

int itk::Ray< TInputImage, TCoordRep >::m_NumberOfVoxelsInY

protected

The dimension in voxels of the 3D volume in along the y axis.

template<class TInputImage , class TCoordRep = double>

int itk::Ray< TInputImage, TCoordRep >::m_NumberOfVoxelsInZ

protected

The dimension in voxels of the 3D volume in along the z axis.

template<class TInputImage , class TCoordRep = double>

int itk::Ray< TInputImage, TCoordRep >::m_NumVoxelPlanesTraversed

protected

The current number of planes of voxels traversed by the ray.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_Position3Dvox[3]

protected

The current coordinate on the ray in voxels.

NB. Two of the components of this coordinate (i.e. those lying within the planes of voxels being traversed) will be shifted by half a voxel. This enables indices of the neighbouring voxels within the plane to be determined by simply casting to 'int' and optionally adding 1.

template<class TInputImage , class TCoordRep = double>

ProjectionMatrixType itk::Ray< TInputImage, TCoordRep >::m_ProjectionMatrix

protected

The combined affine and perspective transformation.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_ProjectionResolution2Dmm[2]

protected

The resolution of the 2D projection image.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_RayDirectionInMM[3]

protected

The direction of the ray.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_RayEndCoordInMM[3]

protected

The coordinate of the point at which the ray exits the volume in mm.

template<class TInputImage , class TCoordRep = double>

int itk::Ray< TInputImage, TCoordRep >::m_RayIntersectionVoxelIndex[3]

protected

The voxel coordinate of the bottom-left voxel of the current four voxels surrounding the ray's trajectory.

template<class TInputImage , class TCoordRep = double>

PixelType* itk::Ray< TInputImage, TCoordRep >::m_RayIntersectionVoxels[4]

protected

Pointers to the current four voxels surrounding the ray's trajectory.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_RayPosition2Dmm[2]

protected

The ray intercept 2D coordinate.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_RayStartCoordInMM[3]

protected

The coordinate of the point at which the ray enters the volume in mm.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_RayVoxelEndPosition[3]

protected

The end coordinate of the ray in voxels.

NB. Two of the components of this coordinate (i.e. those lying within the planes of voxels being traversed) will be shifted by half a voxel. This enables indices of the neighbouring voxels within the plane to be determined by simply casting to 'int' and optionally adding 1.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_RayVoxelStartPosition[3]

protected

The start position of the ray in voxels.

NB. Two of the components of this coordinate (i.e. those lying within the planes of voxels being traversed) will be shifted by half a voxel. This enables indices of the neighbouring voxels within the plane to be determined by simply casting to 'int' and optionally adding 1.

template<class TInputImage , class TCoordRep = double>

int itk::Ray< TInputImage, TCoordRep >::m_TotalRayVoxelPlanes

protected

The total number of planes of voxels traversed by the ray.

template<class TInputImage , class TCoordRep = double>

TraversalDirection itk::Ray< TInputImage, TCoordRep >::m_TraversalDirection

protected

The direction in which the ray is incremented thorough the volume (x, y or z).

template<class TInputImage , class TCoordRep = double>

bool itk::Ray< TInputImage, TCoordRep >::m_ValidRay

protected

Flag indicating whether the current ray is valid.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_VoxelDimensionInX

protected

Voxel dimension in x.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_VoxelDimensionInY

protected

Voxel dimension in y.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_VoxelDimensionInZ

protected

Voxel dimension in z.

template<class TInputImage , class TCoordRep = double>

double itk::Ray< TInputImage, TCoordRep >::m_VoxelIncrement[3]

protected

The incremental direction vector of the ray in voxels.

---

The documentation for this class was generated from the following file:

• itkRay.h