USGS Astrogeology Isis API

This routine allows the programmer to define three or more mappings from (x,y) to (x',y') and will solve for A,B,C,D,E,F.

If the above coefficients can be computed then the inverse of the affine transform exists and will be computed such that

Alternatively (or in combination), translations and rotations can be applied to create a transform.

Definition at line 78 of file Affine.h.


Public Types
typedef TNT::Array2D< double >	AMatrix
Public Member Functions
	Affine ()
	Constructs an Affine transform.
	Affine (const AMatrix &a)
	Create Affine transform from matrix.
	~Affine ()
	Destroys the Affine object.
void	Solve (const double x[], const double y[], const double xp[], const double yp[], int n)
	Given a set of coordinate pairs (n >= 3), compute the affine transform that best fits the points.
void	Identity ()
	Set the forward and inverse affine transform to the identity.
void	Translate (double tx, double ty)
	Apply a translation to the current affine transform.
void	Rotate (double rot)
	Apply a translation to the current affine transform.
void	Scale (double scaleFactor)
	Apply a scale to the current affine transform.
void	Compute (double x, double y)
	Compute (xp,yp) given (x,y).
double	xp () const
	Returns the computed x'.
double	yp () const
	Returns the computed y'.
void	ComputeInverse (double xp, double yp)
	Compute (x,y) given (xp,yp).
double	x () const
	Returns the computed x.
double	y () const
	Returns the computed y.
std::vector< double >	Coefficients (int var)
	Return the affine coeffients for the entered variable (1 or 2).
std::vector< double >	InverseCoefficients (int var)
	Return the inverse affine coeffients for the entered variable (1 or 2).
AMatrix	Forward () const
	Returns the forward Affine matrix.
AMatrix	Inverse () const
	Returns the inverse Affine matrix.
Static Public Member Functions
static AMatrix	getIdentity ()
	Return an Affine identity matrix.
Private Member Functions
void	checkDims (const AMatrix &am) const throw (iException &)
	Checks affine matrix to ensure it is a 3x3 standard form transform.
AMatrix	invert (const AMatrix &a) const throw (iException &)
	Compute the inverse of a matrix.
Private Attributes
AMatrix	p_matrix
	Affine forward matrix.
AMatrix	p_invmat
	Affine inverse matrix.
double	p_x
	x value of the (x,y) coordinate
double	p_y
	y value of the (x,y) coordinate
double	p_xp
	x' value of the (x',y') coordinate
double	p_yp
	y' value of the (x',y') coordinate

Constructor & Destructor Documentation

Isis::Affine::Affine ( )

Constructs an Affine transform.

The default transform is the identity.

Definition at line 41 of file Affine.cpp.

References Identity(), p_x, p_xp, p_y, and p_yp.

Isis::Affine::Affine ( const AMatrix & a )

Create Affine transform from matrix.

This constructor creates the affine transform from a forward matrix. The input matrix is checked for the proper dimensions (3x3) and is then inverted to complete the inverse functionality.

The input matrix must be invertable or an exception will be thrown!

Parameters:

Forward affine matrix

Definition at line 57 of file Affine.cpp.

References checkDims(), invert(), p_invmat, p_matrix, p_x, p_xp, p_y, and p_yp.

Isis::Affine::~Affine ( )

Destroys the Affine object.

Definition at line 65 of file Affine.cpp.

Member Function Documentation

void Isis::Affine::checkDims ( const AMatrix & am ) const throw (iException &) [private]

Checks affine matrix to ensure it is a 3x3 standard form transform.

Parameters:

Affine matrix to validate

Definition at line 259 of file Affine.cpp.

References _FILEINFO_, and Isis::iException::Message().

Referenced by Affine().

vector< double > Isis::Affine::Coefficients ( int var )

Return the affine coeffients for the entered variable (1 or 2).

The coefficients are returned in a 3-dimensional vector

Parameters:

var

The coefficient vector index (1 or 2)

Definition at line 230 of file Affine.cpp.

References p_matrix.

Referenced by Isis::Lo::LoCameraFiducialMap::CreateTrans().

void Isis::Affine::Compute	(	double	x,
		double	y
	)

Compute (xp,yp) given (x,y).

Use the methods xp() and yp() to obtain the results.

Parameters:

	x	The transformation x factor
	y	The transformation y factor

Definition at line 203 of file Affine.cpp.

References p_matrix, p_x, p_xp, p_y, and p_yp.

Referenced by Isis::Chip::Extract(), Isis::Chip::Load(), and Isis::Chip::SetChipPosition().

void Isis::Affine::ComputeInverse	(	double	xp,
		double	yp
	)

Compute (x,y) given (xp,yp).

Use the methods x() and y() to obtain the results.

Parameters:

	xp	The inverse transformation xp factor
	yp	The inverse transformation yp factor

Definition at line 217 of file Affine.cpp.

References p_invmat, p_x, p_xp, p_y, and p_yp.

Referenced by Isis::Chip::SetCubePosition().

AMatrix Isis::Affine::Forward ( ) const [inline]

Returns the forward Affine matrix.

Definition at line 111 of file Affine.h.

References p_matrix.

Referenced by Isis::Chip::Extract(), Isis::Gruen::UpdateAffine(), and Isis::Gruen::UpdateChip().

Affine::AMatrix Isis::Affine::getIdentity ( ) [static]

Return an Affine identity matrix.

Returns:: Affine::AMatrix The identity matrix

Definition at line 72 of file Affine.cpp.

Referenced by Isis::Chip::Extract(), Identity(), Rotate(), Scale(), Translate(), and Isis::Gruen::UpdateChip().

void Isis::Affine::Identity ( )

Set the forward and inverse affine transform to the identity.

That is, xp = x and yp = y for all (x,y).

Definition at line 84 of file Affine.cpp.

References getIdentity(), p_invmat, and p_matrix.

Referenced by Affine(), Isis::Chip::Load(), Isis::Chip::SetSize(), and Isis::Chip::TackCube().

AMatrix Isis::Affine::Inverse ( ) const [inline]

Returns the inverse Affine matrix.

Definition at line 113 of file Affine.h.

References p_invmat.

vector< double > Isis::Affine::InverseCoefficients ( int var )

Return the inverse affine coeffients for the entered variable (1 or 2).

The coefficients are returned in a 3-dimensional vector

Parameters:

var

The inverse coefficient vector index

Definition at line 245 of file Affine.cpp.

References p_invmat.

Referenced by Isis::Lo::LoCameraFiducialMap::CreateTrans().

Affine::AMatrix Isis::Affine::invert ( const AMatrix & a ) const throw (iException &) [private]

Compute the inverse of a matrix.

This method will compute the inverse of an affine matrix for purposes of forward and inverse Affine computations.

Parameters:

Matrix to invert

Returns:: Affine::AMatrix The inverted matrix

Definition at line 279 of file Affine.cpp.

References _FILEINFO_, a, c, Isis::iException::Message(), and U.

Referenced by Affine(), and Solve().

void Isis::Affine::Rotate ( double angle )

Apply a translation to the current affine transform.

Parameters:

angle

degrees of counterclockwise rotation

Definition at line 162 of file Affine.cpp.

References getIdentity(), p_invmat, p_matrix, and Isis::PI().

Referenced by Isis::Chip::Load().

void Isis::Affine::Scale ( double scaleFactor )

Apply a scale to the current affine transform.

Parameters:

scaleFactor

The scale factor

Definition at line 185 of file Affine.cpp.

References getIdentity(), p_invmat, and p_matrix.

Referenced by Isis::Gruen::AdaptiveRegistration(), and Isis::Chip::Load().

void Isis::Affine::Solve	(	const double	x[],
		const double	y[],
		const double	xp[],
		const double	yp[],
		int	n
	)

Given a set of coordinate pairs (n >= 3), compute the affine transform that best fits the points.

If given exactly three coordinates that are not colinear, the fit will be guarenteed to be exact through the points.

Parameters:

	x	The transformation x coordinates
	y	The transformation y coordinates
	xp	The transformation xp coordinates
	yp	The transformation yp coordinates
	n	The number of coordiante pairs