org.openimaj.image.feature.local.keypoints

Class Keypoint

java.lang.Object

org.openimaj.image.feature.local.keypoints.Keypoint

All Implemented Interfaces:

Serializable, Cloneable, FeatureVectorProvider<ByteFV>, LocalFeature<KeypointLocation,ByteFV>, LocalFeatureVectorProvider<KeypointLocation,ByteFV>, LocationProvider<KeypointLocation>, Readable, ReadableASCII, ReadableBinary, ReadWriteable, VariableLength, Writeable, WriteableASCII, WriteableBinary, Coordinate, Point2d, ScaleSpacePoint

Direct Known Subclasses:

AffineSimulationKeypoint, InterestPointKeypoint, MinMaxKeypoint

public class Keypoint
extends Object
implements Serializable, ScaleSpacePoint, LocalFeature<KeypointLocation,ByteFV>, VariableLength, Cloneable

A local interest point with a location, scale, orientation and associated feature. The feature is stored as an array of bytes.

Author:

Jonathon Hare (jsh2@ecs.soton.ac.uk)

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
byte[]	ivec keypoint feature descriptor (i.e.
float	ori dominant orientation of keypoint
float	scale scale of keypoint
float	x x-position of keypoint
float	y y-position of keypoint

Constructor Summary

Constructors

Constructor and Description
Keypoint() Construct with the default feature vector length for SIFT (128).
Keypoint(float x, float y, float ori, float scale, byte[] ivec) Construct with the given parameters.
Keypoint(int length) Construct with the given feature vector length.
Keypoint(Keypoint k) Construct by copying from another Keypoint

Method Summary

Modifier and Type	Method and Description
static List<Keypoint>	addGaussianNoise(List<Keypoint> siftFeatures, double mean, double sigma) Add Gaussian noise the feature vectors of some features.
String	asciiHeader() Header for ascii input.
byte[]	binaryHeader() Header for binary input.
Keypoint	clone()
Point2d	copy() Clone the point
void	copyFrom(Point2d p) Copy the values of the given point into this point.
boolean	equals(Object obj)
int	getDimensions()
ByteFV	getFeatureVector() Get the FeatureVector associated with this object.
KeypointLocation	getLocation() Get the location associated with this object.
Float	getOrdinate(int dimension) Get the ordinate value for a specific dimension.
static List<Keypoint>	getRelativeKeypoints(List<Keypoint> keypoints, float x, float y) Create a list of Keypoints from the input list, but with the positions offset by the given amount.
float	getScale() Get the scale associated with this point.
static List<Keypoint>	getScaledKeypoints(List<Keypoint> keypoints, int toScale) Scale a list of keypoints by the given amount.
float	getX()
float	getY()
int	hashCode()
boolean	locationEquals(Object obj) Test whether the location of this Keypoint and another Keypoint is the same.
Point2d	minus(Point2d a) Take point point from another point such that return = this - a
void	readASCII(Scanner in) Read internal state from in.
void	readBinary(DataInput in) Read internal state from in.
void	setLocation(KeypointLocation location) Set the location of this Keypoint
void	setOrdinate(int dimension, Number value) Set the ordinate value for a specific dimension.
void	setScale(float scale) Set the scale associated with this point.
void	setX(float x) Set x coordinate of point
void	setY(float y) Set y coordinate of point
String	toString()
Keypoint	transform(Jama.Matrix transform) Transform the point by the given matrix
void	translate(float x, float y) Translate the position of the point by the given amounts
void	translate(Point2d v) Translate the position of the point by the given amounts
void	writeASCII(PrintWriter out) Write the content of this as ascii to out.
void	writeBinary(DataOutput out) Write the content of this as binary to out.

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

ivec

public byte[] ivec

keypoint feature descriptor (i.e. SIFT)

ori

public float ori

dominant orientation of keypoint

scale

public float scale

scale of keypoint

x

public float x

x-position of keypoint

y

public float y

y-position of keypoint

Constructor Detail

Keypoint

public Keypoint()

Construct with the default feature vector length for SIFT (128).

Keypoint

public Keypoint(int length)

Construct with the given feature vector length.

Parameters:

length - the length of the feature vector

Keypoint

public Keypoint(float x,
                float y,
                float ori,
                float scale,
                byte[] ivec)

Construct with the given parameters.

Parameters:

x - the x-ordinate of the keypoint

y - the y-ordinate of the keypoint

ori - the orientation of the keypoint

scale - the scale of the keypoint

ivec - the feature vector of the keypoint

Keypoint

public Keypoint(Keypoint k)

Construct by copying from another Keypoint

Parameters:

k - the Keypoint to copy from

Method Detail

getOrdinate

public Float getOrdinate(int dimension)

Description copied from interface: Coordinate

Get the ordinate value for a specific dimension.

Specified by:

getOrdinate in interface Coordinate

Parameters:

dimension - The index of the dimension we are interested in

Returns:

The value of the ordinate of the given dimension.

getDimensions

public int getDimensions()

Specified by:

getDimensions in interface Coordinate

Returns:

The number of dimensions in the coordinate.

getX

public float getX()

Specified by:

getX in interface Point2d

Returns:

x coordinate of point

getY

public float getY()

Specified by:

getY in interface Point2d

Returns:

y coordinate of point

setX

public void setX(float x)

Description copied from interface: Point2d

Set x coordinate of point

Specified by:

setX in interface Point2d

Parameters:

x - x-coordinate

setY

public void setY(float y)

Description copied from interface: Point2d

Set y coordinate of point

Specified by:

setY in interface Point2d

Parameters:

y - y-coordinate

getScale

public float getScale()

Description copied from interface: ScaleSpacePoint

Get the scale associated with this point.

Specified by:

getScale in interface ScaleSpacePoint

Returns:

the scale.

setScale

public void setScale(float scale)

Description copied from interface: ScaleSpacePoint

Set the scale associated with this point.

Specified by:

setScale in interface ScaleSpacePoint

Parameters:

scale - the scale to set.

toString

public String toString()

Overrides:

toString in class Object

locationEquals

public boolean locationEquals(Object obj)

Test whether the location of this Keypoint and another Keypoint is the same.

Parameters:

obj - the other keypoint

Returns:

true if the locations match; false otherwise.

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

clone

public Keypoint clone()

Overrides:

clone in class Object

copyFrom

public void copyFrom(Point2d p)

Description copied from interface: Point2d

Copy the values of the given point into this point.

Specified by:

copyFrom in interface Point2d

Parameters:

p - The point to copy values from.

writeBinary

public void writeBinary(DataOutput out)
                 throws IOException

Description copied from interface: WriteableBinary

Write the content of this as binary to out.

Specified by:

writeBinary in interface WriteableBinary

Parameters:

out - sink to write to

Throws:

IOException - an error writing to out

writeASCII

public void writeASCII(PrintWriter out)
                throws IOException

Description copied from interface: WriteableASCII

Write the content of this as ascii to out.

Specified by:

writeASCII in interface WriteableASCII

Parameters:

out - sink to write to

Throws:

IOException - an error writing to out

readBinary

public void readBinary(DataInput in)
                throws IOException

Description copied from interface: ReadableBinary

Read internal state from in.

Specified by:

readBinary in interface ReadableBinary

Parameters:

in - source to read from.

Throws:

IOException - an error reading input

readASCII

public void readASCII(Scanner in)
               throws IOException

Description copied from interface: ReadableASCII

Read internal state from in.

Specified by:

readASCII in interface ReadableASCII

Parameters:

in - source to read from.

Throws:

IOException - an error reading input

binaryHeader

public byte[] binaryHeader()

Description copied from interface: ReadableBinary

Header for binary input. Will be automatically read by IOUtils when using readBinary().

Specified by:

binaryHeader in interface ReadableBinary

Specified by:

binaryHeader in interface WriteableBinary

Returns:

header

asciiHeader

public String asciiHeader()

Description copied from interface: ReadableASCII

Header for ascii input. Will be automatically read by IOUtils when using readASCII().

Specified by:

asciiHeader in interface ReadableASCII

Specified by:

asciiHeader in interface WriteableASCII

Returns:

header

getFeatureVector

public ByteFV getFeatureVector()

Description copied from interface: FeatureVectorProvider

Get the FeatureVector associated with this object.

Specified by:

getFeatureVector in interface FeatureVectorProvider<ByteFV>

Returns:

the feature vector.

getLocation

public KeypointLocation getLocation()

Description copied from interface: LocationProvider

Get the location associated with this object.

Specified by:

getLocation in interface LocationProvider<KeypointLocation>

Returns:

the location.

setLocation

public void setLocation(KeypointLocation location)

Set the location of this Keypoint

Parameters:

location - the location

getRelativeKeypoints

public static List<Keypoint> getRelativeKeypoints(List<Keypoint> keypoints,
                                                  float x,
                                                  float y)

Create a list of Keypoints from the input list, but with the positions offset by the given amount.

Parameters:

keypoints - the input list

x - the x offset

y - the y offset

Returns:

the new keypoints

addGaussianNoise

public static List<Keypoint> addGaussianNoise(List<Keypoint> siftFeatures,
                                              double mean,
                                              double sigma)

Add Gaussian noise the feature vectors of some features. The original features are untouched; the returned list contains a copy.

Parameters:

siftFeatures - the input features

mean - the mean of the noise

sigma - the standard deviation of the noise

Returns:

the noisy keypoints

getScaledKeypoints

public static List<Keypoint> getScaledKeypoints(List<Keypoint> keypoints,
                                                int toScale)

Scale a list of keypoints by the given amount. This scales the location and scale of each keypoint. The original features are untouched; the returned list contains a copy.

Parameters:

keypoints - the input features.

toScale - the scale factor

Returns:

the scaled features.

translate

public void translate(float x,
                      float y)

Description copied from interface: Point2d

Translate the position of the point by the given amounts

Specified by:

translate in interface Point2d

Parameters:

x - x-amount

y - y-amount

transform

public Keypoint transform(Jama.Matrix transform)

Description copied from interface: Point2d

Transform the point by the given matrix

Specified by:

transform in interface Point2d

Returns:

a copy

minus

public Point2d minus(Point2d a)

Description copied from interface: Point2d

Take point point from another point such that return = this - a

Specified by:

minus in interface Point2d

Returns:

a new point

translate

public void translate(Point2d v)

Description copied from interface: Point2d

Translate the position of the point by the given amounts

Specified by:

translate in interface Point2d

Parameters:

v - the vector to translate by

copy

public Point2d copy()

Description copied from interface: Point2d

Clone the point

Specified by:

copy in interface Point2d

Returns:

a copy of the point

setOrdinate

public void setOrdinate(int dimension,
                        Number value)

Description copied from interface: Coordinate

Set the ordinate value for a specific dimension.

Specified by:

setOrdinate in interface Coordinate

Parameters:

dimension - The index of the dimension we are interested in

value - The value of the ordinate of the given dimension.