#include <visp3/core/vpPolygon.h>

Public Types
enum	PointInPolygonMethod { PnPolySegmentIntersection , PnPolyRayCasting }

Public Member Functions
	vpPolygon ()

VP_EXPLICIT	vpPolygon (const std::vector< vpImagePoint > &corners)

VP_EXPLICIT	vpPolygon (const std::list< vpImagePoint > &corners)

	vpPolygon (const vpPolygon &poly)

virtual	~vpPolygon ()

vpPolygon &	operator= (const vpPolygon &poly)

vpPolygon &	buildFrom (const std::vector< vpImagePoint > &corners, const bool &create_convex_hull=false)

vpPolygon &	buildFrom (const std::list< vpImagePoint > &corners, const bool &create_convex_hull=false)

vpPolygon &	buildFrom (const std::vector< vpPoint > &corners, const vpCameraParameters &cam, const bool &create_convex_hull=false)

unsigned int	getSize () const

void	initClick (const vpImage< unsigned char > &I, unsigned int size=5, const vpColor &color=vpColor::red, unsigned int thickness=1)

void	initClick (const vpImage< vpRGBa > &I, unsigned int size=5, const vpColor &color=vpColor::red, unsigned int thickness=1)

bool	isInside (const vpImagePoint &iP, const PointInPolygonMethod &method=PnPolyRayCasting) const

void	display (const vpImage< unsigned char > &I, const vpColor &color, unsigned int thickness=1) const

const std::vector< vpImagePoint > &	getCorners () const

double	getArea () const

vpImagePoint	getCenter () const

vpRect	getBoundingBox () const

Static Public Member Functions
static bool	isInside (const std::vector< vpImagePoint > &roi, const double &i, const double &j, const PointInPolygonMethod &method=PnPolyRayCasting)

Protected Member Functions
void	init (const std::vector< vpImagePoint > &corners)

void	init (const std::list< vpImagePoint > &corners)

void	updateArea ()

void	updateCenter ()

void	updateBoundingBox ()

Protected Attributes
std::vector< vpImagePoint >	_corners

vpImagePoint	_center

double	_area

bool	_goodPoly

vpRect	_bbox

Detailed Description

Defines a generic 2D polygon.

A polygon is internally represented by N 2D points.

By default three coordinates in the $ (i,j) $ frame (see vpImagePoint class documentation for more details about the frame) are used $ (0,0) $ , $ (1,0) $ and $ (0,1) $ .

The code bellow shows how to manipulate a polygon.

#include <iostream>
 
#include <visp3/core/vpPolygon.h>
 
#ifdef ENABLE_VISP_NAMESPACE
using namespace VISP_NAMESPACE_NAME;
#endif
 
int main()
{
  std::vector<vpImagePoint> corners;
 
  // Initialize the corners vector with 4 points
  corners.push_back( vpImagePoint( 50, 100) );
  corners.push_back( vpImagePoint( 50, 300) );
  corners.push_back( vpImagePoint(200, 300) );
  corners.push_back( vpImagePoint(200, 100) );
 
  // Initialize a polygon with the corners
  vpPolygon polygon(corners);
 
  // Get the polygon bounding box
  vpRect bbox = polygon.getBoundingBox();
  std::cout << "Bounding box: " << bbox.getTopLeft() << " to "
            << bbox.getBottomRight() << std::endl;
 
  // Get the polygon surface and center
  std::cout << "Area: " << polygon.getArea() << std::endl;
  std::cout << "Center: " << polygon.getCenter() << std::endl;
 
  // Check if a point is inside the polygon
  vpImagePoint ip(550, 200);
  std::cout << "The point " << ip << " is "
            << (polygon.isInside(ip) ? "inside":"outside")
            << " the polygon" << std::endl;
 
  return 0;
}

Examples: catchPolygon2.cpp, mbot-apriltag-2D-half-vs.cpp, testDisplayPolygonLines.cpp, testDisplays.cpp, testPolygon.cpp, tutorial-flood-fill.cpp, and tutorial-pose-from-planar-object.cpp.

Definition at line 102 of file vpPolygon.h.

Member Enumeration Documentation

◆ PointInPolygonMethod

enum vpPolygon::PointInPolygonMethod

Enumerator
PnPolySegmentIntersection	Legacy Point In Polygon test.
PnPolyRayCasting	Point In Polygon test using ray casting method (faster).

Definition at line 105 of file vpPolygon.h.

Constructor & Destructor Documentation

◆ vpPolygon() [1/4]

BEGIN_VISP_NAMESPACE vpPolygon::vpPolygon ( )

Default constructor that creates an empty polygon.

Definition at line 114 of file vpPolygon.cpp.

◆ vpPolygon() [2/4]

vpPolygon::vpPolygon ( const std::vector< vpImagePoint > & corners )

Constructor which initialises the polygon thanks to the given corners.

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners : The Points defining the corners.

Definition at line 126 of file vpPolygon.cpp.

References _goodPoly, and init().

◆ vpPolygon() [3/4]

vpPolygon::vpPolygon ( const std::list< vpImagePoint > & corners )

Constructor which initialises the polygon thanks to the given corners.

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners : The Points defining the corners.

Definition at line 143 of file vpPolygon.cpp.

References _goodPoly, and init().

◆ vpPolygon() [4/4]

vpPolygon::vpPolygon ( const vpPolygon & poly )

Copy constructor

Parameters

poly	: The polygon used for the initialisation.

Definition at line 157 of file vpPolygon.cpp.

◆ ~vpPolygon()

vpPolygon::~vpPolygon ( )

virtual

Basic destructor

Definition at line 165 of file vpPolygon.cpp.

Member Function Documentation

◆ buildFrom() [1/3]

vpPolygon & vpPolygon::buildFrom	(	const std::list< vpImagePoint > &	corners,
		const bool &	create_convex_hull = `false`
	)

Initialises the polygon thanks to the collection of 2D points (in pixel).

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners	: The corners of the polygon.
create_convex_hull	Create a convex hull from the given corners.

Definition at line 217 of file vpPolygon.cpp.

References init(), and vpException::notImplementedError.

◆ buildFrom() [2/3]

vpPolygon & vpPolygon::buildFrom	(	const std::vector< vpImagePoint > &	corners,
		const bool &	create_convex_hull = `false`
	)

Initialises the triangle thanks to the collection of 2D points (in pixel).

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners	: The corners of the polygon.
create_convex_hull	Create a convex hull from the given corners.

Examples: catchPolygon2.cpp, testPolygon.cpp, and tutorial-pose-from-planar-object.cpp.

Definition at line 193 of file vpPolygon.cpp.

References init(), and vpException::notImplementedError.

Referenced by buildFrom(), and initClick().

◆ buildFrom() [3/3]

vpPolygon & vpPolygon::buildFrom	(	const std::vector< vpPoint > &	corners,
		const vpCameraParameters &	cam,
		const bool &	create_convex_hull = `false`
	)

Initialises the triangle thanks to the collection of 2D points (in meter). The fields x and y are used to compute the corresponding coordinates in pixel thanks to the camera parameters cam.

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners	: The corners of the polygon.
cam	: The camera parameters used to convert the coordinates from meter to pixel.
create_convex_hull	Create a convex hull from the given corners.

Definition at line 244 of file vpPolygon.cpp.

References buildFrom(), and vpMeterPixelConversion::convertPoint().

◆ display()

void vpPolygon::display	(	const vpImage< unsigned char > &	I,
		const vpColor &	color,
		unsigned int	thickness = `1`
	)		const

Display the polygon in the image (overlay, so the image is not modified). A call to the flush() method is necessary.

Parameters

I	: The image where the polygon is displayed.
color	: The color of the polygon's lines.
thickness	: The thickness of the polygon's lines.

Examples: testPolygon.cpp.

Definition at line 610 of file vpPolygon.cpp.

References _corners, and vpDisplay::displayLine().

◆ getArea()

double vpPolygon::getArea ( ) const

inline

Return the area of the polygon. The area is computed when the polygon is built from the corners.

Returns: The area of the polygon.

Examples: mbot-apriltag-2D-half-vs.cpp, and testPolygon.cpp.

Definition at line 148 of file vpPolygon.h.

Referenced by vpPose::computePlanarObjectPoseFromRGBD(), and vpMbtPolygon::isVisible().

◆ getBoundingBox()

vpRect vpPolygon::getBoundingBox ( ) const

inline

Return the bounding box. The bounding box is the smallest rectangle containing all the polygon.

Returns: The bounding box of the polygon.

Examples: testPolygon.cpp.

Definition at line 164 of file vpPolygon.h.

Referenced by vpMbtFaceDepthDense::computeDesiredFeatures(), vpMbtFaceDepthNormal::computeDesiredFeatures(), vpPose::computePlanarObjectPoseFromRGBD(), and vpKeyPoint::matchPointAndDetect().

◆ getCenter()

vpImagePoint vpPolygon::getCenter ( ) const

inline

Return the center of the polygon. The center is computed when the polygon is built from the corners.

Returns: The area of the polygon.

Examples: testPolygon.cpp.

Definition at line 156 of file vpPolygon.h.

◆ getCorners()

const std::vector<vpImagePoint>& vpPolygon::getCorners ( ) const

inline

Get the corners of the polygon.

Returns: A reference to the corners.

Examples: testDisplayPolygonLines.cpp, testPolygon.cpp, and tutorial-flood-fill.cpp.

Definition at line 140 of file vpPolygon.h.

◆ getSize()

unsigned int vpPolygon::getSize ( ) const

Return number of corners belonging to the polygon.

Definition at line 639 of file vpPolygon.cpp.

References _corners.

◆ init() [1/2]

void vpPolygon::init ( const std::list< vpImagePoint > & corners )

protected

Initialises the polygon using the collection of image points. This method computes some internal variables such as center, area, ...

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners : The corners of the polygon.

Definition at line 342 of file vpPolygon.cpp.

References _corners, updateArea(), updateBoundingBox(), and updateCenter().

◆ init() [2/2]

void vpPolygon::init ( const std::vector< vpImagePoint > & corners )

protected

Initialises the polygon using the collection of image points. This method computes some internal variables such as center, area, ...

Warning: the corners must be ordered (either clockwise or counter clockwise).

Parameters

corners : The corners of the polygon.

Definition at line 322 of file vpPolygon.cpp.

References _corners, updateArea(), updateBoundingBox(), and updateCenter().

Referenced by buildFrom(), and vpPolygon().

◆ initClick() [1/2]

void vpPolygon::initClick	(	const vpImage< unsigned char > &	I,
		unsigned int	size = `5`,
		const vpColor &	color = `vpColor::red`,
		unsigned int	thickness = `1`
	)

Initialises the polygon by (left-)clicking to add a corners to the polygon. A right click is used to stop the addition of new corners.

Parameters

I	: The image where to click to initialise the corners.
size	: Cross size in terms of number of pixels that is displayed over a polygon corner.
color	: Color used to display the cross over the polygon corner.
thickness	: Thickness used to display the cross.

Examples: testDisplayPolygonLines.cpp, testPolygon.cpp, and tutorial-flood-fill.cpp.

Definition at line 265 of file vpPolygon.cpp.

References buildFrom(), vpMouseButton::button1, vpDisplay::displayCross(), vpDisplay::flush(), and vpDisplay::getClick().

◆ initClick() [2/2]

void vpPolygon::initClick	(	const vpImage< vpRGBa > &	I,
		unsigned int	size = `5`,
		const vpColor &	color = `vpColor::red`,
		unsigned int	thickness = `1`
	)

Initialises the polygon by (left-)clicking to add a corners to the polygon. A right click is used to stop the addition of new corners.

Parameters

I	: The image where to click to initialise the corners.
size	: Size of the cross in terms of number of pixels that is displayed over a polygon corner.
color	: Color used to display the cross over the polygon corner.
thickness	: Thickness used to display the cross.

Definition at line 294 of file vpPolygon.cpp.

References buildFrom(), vpMouseButton::button1, vpDisplay::displayCross(), vpDisplay::flush(), and vpDisplay::getClick().

◆ isInside() [1/2]

bool vpPolygon::isInside	(	const std::vector< vpImagePoint > &	roi,
		const double &	i,
		const double &	j,
		const PointInPolygonMethod &	method = `PnPolyRayCasting`
	)

static

Test if an image point is inside a 2D polygon.

Parameters

roi	: List of the polygon corners.
i	: i-coordinate of the image point to test.
j	: j-coordinate of the image point to test.
method	: Method to use for Point In Polygon test.

Returns: True if the point defined by (i,j) is inside the polygon, False otherwise.

Definition at line 629 of file vpPolygon.cpp.

References isInside().

◆ isInside() [2/2]

bool vpPolygon::isInside	(	const vpImagePoint &	ip,
		const PointInPolygonMethod &	method = `PnPolyRayCasting`
	)		const

Check if the 2D point is inside the polygon.

Parameters

ip	: The point which have to be tested.
method	: Method to use for Point In Polygon test.

Returns: Returns true if the point is inside the polygon, false otherwise.

Examples: testPolygon.cpp.

Definition at line 400 of file vpPolygon.cpp.

References _corners, vpImagePoint::get_i(), vpImagePoint::get_j(), vpImagePoint::get_u(), vpImagePoint::get_v(), PnPolySegmentIntersection, vpImagePoint::set_i(), and vpImagePoint::set_j().

Referenced by vpKeyPoint::compute3DForPointsOnCylinders(), vpMbtFaceDepthDense::computeDesiredFeatures(), vpMbtFaceDepthNormal::computeDesiredFeatures(), vpPose::computePlanarObjectPoseFromRGBD(), and isInside().

◆ operator=()

vpPolygon & vpPolygon::operator= ( const vpPolygon & poly )

Equal operator.

Assign poly to this polygon and return a reference to it.

Definition at line 172 of file vpPolygon.cpp.

References _area, _bbox, _center, _corners, and _goodPoly.

◆ updateArea()

void vpPolygon::updateArea ( )

protected

Update the _area attribute of the polygon using the corners.

The area is computed using the formula:

$A = \frac{1}{2} \sum_{i=0}^{n-1} (x_1 y_{i+1} - x_{i+1} y_{i})$

Definition at line 505 of file vpPolygon.cpp.

References _area, _corners, and _goodPoly.

Referenced by init().

◆ updateBoundingBox()

void vpPolygon::updateBoundingBox ( )

protected

Update bounding box of the polygon.

See also: getBoundingBox()

Definition at line 572 of file vpPolygon.cpp.

References _bbox, _corners, _goodPoly, vpRect::setBottomRight(), and vpRect::setTopLeft().

Referenced by init().

◆ updateCenter()

void vpPolygon::updateCenter ( )

protected

Update the _center attribute of the polygon using the corners.

The i coordinate is computed using:

$i = \frac{1}{6{area}} \sum_{i=0}^{n-1} (i_i + i_{i+1})(i_{i+1} j_i - j_{i+1} i_i)$

The computation of the j coordinate is similar.

Definition at line 537 of file vpPolygon.cpp.

References _area, _center, _corners, _goodPoly, vpImagePoint::set_i(), and vpImagePoint::set_j().

Referenced by init().

Member Data Documentation

◆ _area

double vpPolygon::_area

protected

Area of the polygon.

Definition at line 186 of file vpPolygon.h.

Referenced by operator=(), updateArea(), and updateCenter().

◆ _bbox

vpRect vpPolygon::_bbox

protected

Bounding box containing the polygon.

Definition at line 191 of file vpPolygon.h.

Referenced by operator=(), and updateBoundingBox().

◆ _center

vpImagePoint vpPolygon::_center

protected

Center of the polygon. It is automatically computed when the corners are set.

Definition at line 184 of file vpPolygon.h.

Referenced by operator=(), and updateCenter().

◆ _corners

std::vector<vpImagePoint> vpPolygon::_corners

protected

Collection of image points containing the corners.

Definition at line 181 of file vpPolygon.h.

Referenced by display(), getSize(), init(), isInside(), operator=(), updateArea(), updateBoundingBox(), and updateCenter().

◆ _goodPoly

bool vpPolygon::_goodPoly

protected

Flag set to true when the polygon is a good polygon (ie. it has more than two corners) or false otherwise.

Definition at line 189 of file vpPolygon.h.

Referenced by operator=(), updateArea(), updateBoundingBox(), updateCenter(), and vpPolygon().

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

◆ PointInPolygonMethod

Constructor & Destructor Documentation

◆ vpPolygon() [1/4]

◆ vpPolygon() [2/4]

◆ vpPolygon() [3/4]

◆ vpPolygon() [4/4]

◆ ~vpPolygon()

Member Function Documentation

◆ buildFrom() [1/3]

◆ buildFrom() [2/3]

◆ buildFrom() [3/3]

◆ display()

◆ getArea()

◆ getBoundingBox()

◆ getCenter()

◆ getCorners()

◆ getSize()

◆ init() [1/2]

◆ init() [2/2]

◆ initClick() [1/2]

◆ initClick() [2/2]

◆ isInside() [1/2]

◆ isInside() [2/2]

◆ operator=()

◆ updateArea()

◆ updateBoundingBox()

◆ updateCenter()

Member Data Documentation

◆ _area

◆ _bbox

◆ _center

◆ _corners

◆ _goodPoly