#include <HoughLineDetector.h>

Inheritance diagram for icl::cv::HoughLineDetector:

Public Member Functions
	HoughLineDetector (float dRho=0.1, float dR=10, const utils::Range32f &rRange=utils::Range32f(0,::sqrt(640 640+480 480)), float rInhibitionRange=10, float rhoInhibitionRange=0.3, bool gaussianInhibition=true, bool blurHoughSpace=true, bool dilateEntries=true, bool blurredSampling=false)
	Create a new HoughLineDetectorInstance. More...

	~HoughLineDetector ()

void	add (const utils::Point &p)
	adds a new point More...

void	add (const std::vector< utils::Point > &ps)
	adds new points More...

void	add (const utils::Point32f &p)
	adds a new point More...

void	add (const std::vector< utils::Point32f > &ps)
	adds new points More...

template<class T >
void	add (const math::FixedColVector< T, 2 > &p)
	adds a new point More...

template<class T >
void	add (const std::vector< const math::FixedColVector< T, 2 > > &ps)
	adds new points More...

void	add (const core::Img8u &binaryImage)
	adds all non zero pixels of the given binary image More...

const core::Img32s &	getImage () const
	returns current hough-table image More...

const core::Img32f &	getInhibitionMap () const
	returns current gaussian inhibition map More...

void	reset ()
	sets all hough table entries to 0 More...

std::vector< math::StraightLine2D >	getLines (int max, bool resetAfterwards=true)
	detects up to max lines More...

std::vector< math::StraightLine2D >	getLines (int max, std::vector< float > &significances, bool resetAfterwards=true)
	detects up to max lines and pushes the line significances into given destination vector More...

Public Member Functions inherited from icl::utils::Configurable
virtual	~Configurable ()
	virtual destructor More...

	Configurable (const Configurable &other)
	Copy constructor. More...

Configurable &	operator= (const Configurable &other)
	Assignment operator. More...

void	setConfigurableID (const std::string &ID)
	sets the ID of this configurable More...

const std::string &	getConfigurableID () const
	returns the configurables static ID More...

bool	isOrderedFlagSet () const
	returns whether the ordered flag is set More...

void	deactivateProperty (const std::string &pattern)
	adds an additional deativation pattern More...

void	deleteDeactivationPattern (const std::string &pattern)
	removed a formerly added deactivation pattern More...

std::vector< std::string >	getPropertyListWithoutDeactivated () const
	this returns a filtered list of properties (using all filters added by deactivateProperty) More...

virtual void	adaptProperty (const std::string &name, const std::string &newType, const std::string &newInfo, const std::string &newToolTip)
	this function can be used to adapt a specific property afterwards More...

void	registerCallback (const Callback &cb)
	add a callback for changed properties More...

void	removedCallback (const Callback &cb)
	removes a callback that was registered before More...

void	syncChangesTo (Configurable *others, int num=1)
	this can be used to let this instance also apply property changes to others More...

virtual void	setPropertyValue (const std::string &propertyName, const Any &value)
	sets a property value More...

virtual std::vector< std::string >	getPropertyList () const
	returns a list of All properties, that can be set using setProperty More...

virtual bool	supportsProperty (const std::string &propertyName) const
	base implementation for property check (seaches in the property list) More...

virtual void	saveProperties (const std::string &filename, const std::vector< std::string > &propertiesToSkip=EMPTY_VEC) const
	writes all available properties into a file More...

virtual void	loadProperties (const std::string &filename, const std::vector< std::string > &propertiesToSkip=EMPTY_VEC)
	reads a camera config file from disc More...

virtual std::string	getPropertyType (const std::string &propertyName) const
	get type of property More...

virtual std::string	getPropertyInfo (const std::string &propertyName) const
	get information of a properties valid values More...

virtual Any	getPropertyValue (const std::string &propertyName) const
	returns the current value of a property or a parameter More...

virtual std::string	getPropertyToolTip (const std::string &propertyName) const
	returns the tooltip description for a given property More...

virtual int	getPropertyVolatileness (const std::string &propertyName) const
	Returns whether this property may be changed internally. More...

Private Member Functions
void	prepare_all ()

void	prepare (float dRho, float dR, const utils::Range32f &rRange, float rInhibitionRange, float rhoInhibitionRange, bool gaussianInhibition=true, bool blurHoughSpace=true, bool dilateEntries=true, bool blurredSampling=false)
	initializes the HoughLineDetector More...

float	r (float rho, float x, float y) const
	internal utility function More...

int	getX (float rho) const
	internal utility function More...

int	getY (float r) const
	internal utility function More...

float	getRho (int x) const
	internal utility function More...

float	getR (int y) const
	internal utility function More...

void	incLut (float rho, float r)
	internal utility function More...

void	incLutBlurred (float rho, float r)
	internal utility function More...

int &	cyclicLUT (int x, int y)
	internal utility function More...

void	apply_inhibition (const utils::Point &p)
	internal utility function More...

void	add_intern (float x, float y)
	internal utility function More...

void	add_intern2 (float x, float y)
	internal utility function More...

void	blur_hough_space_if_necessary ()
	internal utility function More...

Private Attributes
Data *	m_data

Additional Inherited Members
Public Types inherited from icl::utils::Configurable
typedef Function< void, const Property & >	Callback
	Function type for changed properties. More...

Static Public Member Functions inherited from icl::utils::Configurable
static std::string	create_default_ID (const std::string &prefix)
	this function can be used in subclasses to create a default ID More...

static Configurable *	get (const std::string &id)
	returns configurable by given ID More...

static void	register_configurable_type (const std::string &classname, Function< Configurable * > creator)
	registers a configurable type More...

static std::vector< std::string >	get_registered_configurables ()
	returns a list of all registered configurable classnames More...

static Configurable *	create_configurable (const std::string &classname)
	creates a configurable by given name More...

Static Public Attributes inherited from icl::utils::Configurable
static const std::vector< std::string >	EMPTY_VEC
	used as shortcut – just an empty vector of std::strings More...

Protected Member Functions inherited from icl::utils::Configurable
void	addProperty (const std::string &name, const std::string &type, const std::string &info, const Any &value=Any(), const int volatileness=0, const std::string &tooltip=std::string())
	This can be used by derived classes to store supported properties in the internal list. More...

void	addChildConfigurable (Configurable *configurable, const std::string &childPrefix="")
	This adds another configurable as child. More...

void	removeChildConfigurable (Configurable *configurable)
	removes the given child configurable More...

Property &	prop (const std::string &propertyName)
	this CAN be used e.g. to store a property value in internal property-list More...

const Property &	prop (const std::string &propertyName) const
	this CAN be used e.g. to store a property value in internal property-list More...

	Configurable (const std::string &ID="", bool ordered=true)
	create this configurable with given ID More...

void	call_callbacks (const std::string &propertyName, const Configurable *caller) const
	calls all registered callbacks More...

Protected Attributes inherited from icl::utils::Configurable
std::vector< Callback >	callbacks
	internally managed list of callbacks More...

Detailed Description

LineDetection class using hough-space line detection

Algorithms

Image lines (of infinite length) can be described by a tuple (rho,r) and the line equation $r = x\cdot cos(rho) + y\cdot sin(rho)$ . Each pixel (x,y) belongs potentially to a all lines (rho,r) where this equation is true. Internally, the space of possible lines (sometimes referred a the hough-space) is sampled (internally we use an instance of core::Img32s). Rho is mapped to the x-axis (x=0 -> rho=0, x=width-1 -> rho = 2*M_PI) and r is mapped to the y-axis (y=0 -> r=minR, y=height-1 -> r=maxR). So the size of the internal hough-space becomes 2*M_PI/dRho x (rRange.max-rRange.min)/dR.

When a new border pixel (x,y) is added, the probability of each potential line that intersects (x,y) is increased. Technically this is performed by computing r(rho) for all possible values rho (all samples) with the formula for r above which leads to values (rho,r) which's hough-space entries are increased by one. The best line matches can be computed from the maxima in the resulting hough space.

Optimizations

To enhance line detection performance, the HoughLineDetector provides a set of optimization approaches:

Local inhibition around detected lines

As a single image line, might result in 2 or even more lines in the hough-space (because of spacial noise in the pixels detection procedure), the hough-space is locally inhibited around already detected lines. The amount of this inhibition procedure can be set by the constructor parameters (rInhibitionRange and rhoInhibitionRange).

Gaussian inhibition

Sometimes hard borders of the inhibition sub-window lead to random 2nd and 3rd detected line values. To stabilize this, inhibition can be set up to be 'gaussian-blurred', which means, that hough-table entries that are very close to already detected lines are nearly removed completely and those that are also in the inhibition sub-rect but some pixels away from the detected line center are inhibited less.

Gaussian inhibition

Resulting from the sampling procedure of both, that actual image space and the hough-space, entries in the hough-space might have hard borders or even gaps. To avoid this, three different optimization techniques are provided, which can all be combined.

Blurring the hough space

This means, that the hough-space is simply blurred using a 3x3 linear gaussian filter. This optimization provides much more stable results, but it also entails a higher computational expense.

Dilation of pixel entries

If this optimization is activated, no only the given pixel (x,y) is added internally, but also it's 4 direct neighbour pixels. This also leads to a kind of blurred hough table

Blurred sampling of lines

This optimization changes the line-sampling procedure. When a line is sampled for all rho-values using r = x cos(rho) + y sin(rho), not only the resulting pixel p in the hough table is increased, but also the pixel above, and the pixel below (actually, the exactly computed pixel p is increased by 2 and it's upper and lower neighbour's are increased by one). This again leads to a blurring effect. however, the other two optimzations provides better results. It's worth mention, that this optimization's additional computational expense is low in comparison to the other two optizations.

Constructor & Destructor Documentation

◆ HoughLineDetector()

icl::cv::HoughLineDetector::HoughLineDetector	(	float	dRho = `0.1`,
		float	dR = `10`,
		const utils::Range32f &	rRange = `utils::Range32f(0,::sqrt(640 640+480 480))`,
		float	rInhibitionRange = `10`,
		float	rhoInhibitionRange = `0.3`,
		bool	gaussianInhibition = `true`,
		bool	blurHoughSpace = `true`,
		bool	dilateEntries = `true`,
		bool	blurredSampling = `false`
	)

Create a new HoughLineDetectorInstance.

Parameters

dRho	line angle sampling distance
dR	line distance to 0 sampling factor
rRange	range of line distances
rInhibitionRange	vertical radius for local inhibition
rhoInhibitionRange	horizontal radius for local inhibition
gaussianInhibition	enables gaussian inhibition
blurHoughSpace	enables hough space blurring
dilateEntries	enables entry dilatation
blurredSampling	enables blurred sampling

◆ ~HoughLineDetector()

icl::cv::HoughLineDetector::~HoughLineDetector ( )

Member Function Documentation

◆ add() [1/7]

void icl::cv::HoughLineDetector::add ( const utils::Point & p )

adds a new point

◆ add() [2/7]

void icl::cv::HoughLineDetector::add ( const std::vector< utils::Point > & ps )

adds new points

◆ add() [3/7]

void icl::cv::HoughLineDetector::add ( const utils::Point32f & p )

adds a new point

◆ add() [4/7]

void icl::cv::HoughLineDetector::add ( const std::vector< utils::Point32f > & ps )

adds new points

◆ add() [5/7]

template<class T >

void icl::cv::HoughLineDetector::add ( const math::FixedColVector< T, 2 > & p )

inline

adds a new point

◆ add() [6/7]

template<class T >

void icl::cv::HoughLineDetector::add ( const std::vector< const math::FixedColVector< T, 2 > > & ps )

inline

adds new points

◆ add() [7/7]

void icl::cv::HoughLineDetector::add ( const core::Img8u & binaryImage )

adds all non zero pixels of the given binary image

◆ add_intern()

void icl::cv::HoughLineDetector::add_intern	(	float	x,
		float	y
	)

private

internal utility function

◆ add_intern2()

void icl::cv::HoughLineDetector::add_intern2	(	float	x,
		float	y
	)

private

internal utility function

◆ apply_inhibition()

void icl::cv::HoughLineDetector::apply_inhibition ( const utils::Point & p )

private

internal utility function

◆ blur_hough_space_if_necessary()

void icl::cv::HoughLineDetector::blur_hough_space_if_necessary ( )

private

internal utility function

◆ cyclicLUT()

int& icl::cv::HoughLineDetector::cyclicLUT	(	int	x,
		int	y
	)

private

internal utility function

◆ getImage()

const core::Img32s& icl::cv::HoughLineDetector::getImage ( ) const

returns current hough-table image

◆ getInhibitionMap()

const core::Img32f& icl::cv::HoughLineDetector::getInhibitionMap ( ) const

returns current gaussian inhibition map

◆ getLines() [1/2]

std::vector<math::StraightLine2D> icl::cv::HoughLineDetector::getLines	(	int	max,
		bool	resetAfterwards = `true`
	)

detects up to max lines

◆ getLines() [2/2]

std::vector<math::StraightLine2D> icl::cv::HoughLineDetector::getLines	(	int	max,
		std::vector< float > &	significances,
		bool	resetAfterwards = `true`
	)

detects up to max lines and pushes the line significances into given destination vector

significances are relative to the first line match, which's significance is always 1.0

◆ getR()

float icl::cv::HoughLineDetector::getR ( int y ) const

private

internal utility function

◆ getRho()

float icl::cv::HoughLineDetector::getRho ( int x ) const

private

internal utility function

◆ getX()

int icl::cv::HoughLineDetector::getX ( float rho ) const

private

internal utility function

◆ getY()

int icl::cv::HoughLineDetector::getY ( float r ) const

private

internal utility function

◆ incLut()

void icl::cv::HoughLineDetector::incLut	(	float	rho,
		float	r
	)

private

internal utility function

◆ incLutBlurred()

void icl::cv::HoughLineDetector::incLutBlurred	(	float	rho,
		float	r
	)

private

internal utility function

◆ prepare()

void icl::cv::HoughLineDetector::prepare	(	float	dRho,
		float	dR,
		const utils::Range32f &	rRange,
		float	rInhibitionRange,
		float	rhoInhibitionRange,
		bool	gaussianInhibition = `true`,
		bool	blurHoughSpace = `true`,
		bool	dilateEntries = `true`,
		bool	blurredSampling = `false`
	)

private

initializes the HoughLineDetector

◆ prepare_all()

void icl::cv::HoughLineDetector::prepare_all ( )

private

◆ r()

float icl::cv::HoughLineDetector::r	(	float	rho,
		float	x,
		float	y
	)		const

private

internal utility function

◆ reset()

void icl::cv::HoughLineDetector::reset ( )

sets all hough table entries to 0

Member Data Documentation

◆ m_data

Data* icl::cv::HoughLineDetector::m_data

private

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

/Users/alneuman/vm/icl/ICLCV/src/ICLCV/HoughLineDetector.h

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Detailed Description

Algorithms

Optimizations

Local inhibition around detected lines

Gaussian inhibition

Gaussian inhibition

Blurring the hough space

Dilation of pixel entries

Blurred sampling of lines

Constructor & Destructor Documentation

◆ HoughLineDetector()

◆ ~HoughLineDetector()

Member Function Documentation

◆ add() [1/7]

◆ add() [2/7]

◆ add() [3/7]

◆ add() [4/7]

◆ add() [5/7]

◆ add() [6/7]

◆ add() [7/7]

◆ add_intern()

◆ add_intern2()

◆ apply_inhibition()

◆ blur_hough_space_if_necessary()

◆ cyclicLUT()

◆ getImage()

◆ getInhibitionMap()

◆ getLines() [1/2]

◆ getLines() [2/2]

◆ getR()

◆ getRho()

◆ getX()

◆ getY()

◆ incLut()

◆ incLutBlurred()

◆ prepare()

◆ prepare_all()

◆ r()

◆ reset()

Member Data Documentation

◆ m_data