ImagePoint¶

class ImagePoint(*args, **kwargs)¶

Bases: pybind11_object

Class that defines a 2D point in an image. This class is useful for image processing and stores only the 2D coordinates given in sub-pixel .

Warning

If you want to define a point thanks to its coordinates given in meter in the object frame, the camera frame or the image plane, you have to use the class vpPoint .

In this class, the 2D coordinates are not necessary integer values. It is easy to manipulate the given coordinates in the two frames used in ViSP : the (i,j) coordinates and the (u,v) coordinates. The two following images illustrate the two coordinate systems.

Warning

An instance of the vpImagePoint class corresponds to a particular point. Thus, if you change the point coordinate using the method set_i(double i) , it produces the same effect than if you used the method set_v(double v) . These two methods change the same private attribute. It is also true for the two methods set_j(double j) and set_u(double u) .

Overloaded function.

__init__(self: visp._visp.core.ImagePoint) -> None

Default constructor that initialize the coordinates of the image point to zero.

__init__(self: visp._visp.core.ImagePoint, ii: float, jj: float) -> None

Default constructor that initialize the coordinates of the image thanks to the parameters \(ii\) and \(jj\) .

__init__(self: visp._visp.core.ImagePoint, ip: visp._visp.core.ImagePoint) -> None

Copy constructor.

Initialize the coordinates of the image point with ip .

Parameters:

ip: An image point.

Methods

`__init__`	Overloaded function.
`distance`	Compute the distance \(\|iP1 - iP2\| = \sqrt{(i_1-i_2)^2+(j_1-j_2)^2}\)
`getBBox`	param ipVec: Vector of input image points.
`get_i`	Gets the point coordinate corresponding to the \(i\) axes in the frame (i,j).
`get_j`	Gets the point coordinate corresponding to the \(j\) axes in the frame (i,j).
`get_u`	Gets the point coordinate corresponding to the \(u\) axes in the frame (u,v).
`get_v`	Gets the point coordinate corresponding to the \(v\) axes in the frame (u,v).
`inRectangle`	Check if an image point belongs to a rectangle.
`inSegment`	Test if the image point belongs to a segment represented by two image points.
`nextInSegment`	Considering current image point, returns the next image point that belongs to the segment [start,end].
`set_i`	Sets the point coordinate corresponding to the \(i\) axes in the frame (i,j).
`set_ij`	Sets the point coordinates in the frame (i,j).
`set_j`	Sets the point coordinate corresponding to the \(j\) axes in the frame (i,j).
`set_u`	Sets the point coordinate corresponding to the \(u\) axes in the frame (u,v).
`set_uv`	Sets the point coordinates in the frame (u,v).
`set_v`	Sets the point coordinate corresponding to the \(v\) axes in the frame (u,v).
`sqrDistance`	Compute the distance \(\|iP1 - iP2\| = (i_1-i_2)^2+(j_1-j_2)^2\)

Inherited Methods

Operators

`__doc__`
`__iadd__`	Operator +=.
`__imul__`	Operator *=.
`__init__`	Overloaded function.
`__isub__`	Operator -=.
`__itruediv__`	Operator /=.
`__module__`
`__repr__`

Attributes

`__annotations__`

__iadd__(self, ip: visp._visp.core.ImagePoint) → visp._visp.core.ImagePoint¶

Operator +=.

This operator can be used to compute the center of gravity of a set of image points.

#include <iostream>
#include <vector>
#include <visp3/core/vpImagePoint.h>

int main()
{
  std::vector<vpImagePoint> ip(2);

  ip[0].set_ij(100, 200);
  ip[1].set_ij(300, 400);

  vpImagePoint cog(0,0);
  for(unsigned int i=0; i<ip.size(); ++i)
    cog += ip[i];
  cog /= ip.size();
  std::cout << "cog: " << cog << std::endl;
}

__imul__(self, scale: float) → visp._visp.core.ImagePoint¶: Operator *=.

__init__(*args, **kwargs)¶

Overloaded function.

__init__(self: visp._visp.core.ImagePoint) -> None

Default constructor that initialize the coordinates of the image point to zero.

__init__(self: visp._visp.core.ImagePoint, ii: float, jj: float) -> None

Default constructor that initialize the coordinates of the image thanks to the parameters \(ii\) and \(jj\) .

__init__(self: visp._visp.core.ImagePoint, ip: visp._visp.core.ImagePoint) -> None

Copy constructor.

Initialize the coordinates of the image point with ip .

Parameters:

ip: An image point.

__isub__(self, ip: visp._visp.core.ImagePoint) → visp._visp.core.ImagePoint¶: Operator -=.

__itruediv__(self, scale: float) → visp._visp.core.ImagePoint¶

Operator /=.

This operator can be used to compute the center of gravity of a set of image points.

#include <iostream>
#include <vector>
#include <visp3/core/vpImagePoint.h>

int main()
{
  std::vector<vpImagePoint> ip(2);

  ip[0].set_ij(100, 200);
  ip[1].set_ij(300, 400);

  vpImagePoint cog(0,0);
  for(unsigned int i=0; i<ip.size(); ++i)
    cog += ip[i];
  cog /= ip.size();
  std::cout << "cog: " << cog << std::endl;
}

static distance(iP1: visp._visp.core.ImagePoint, iP2: visp._visp.core.ImagePoint) → float¶

Compute the distance \(|iP1 - iP2| = \sqrt{(i_1-i_2)^2+(j_1-j_2)^2}\)

Parameters:

iP1: visp._visp.core.ImagePoint¶: First point
iP2: visp._visp.core.ImagePoint¶: Second point

Returns:

the distance between the two points.

static getBBox(ipVec: list[visp._visp.core.ImagePoint]) → visp._visp.core.Rect¶

Parameters:

ipVec: list[visp._visp.core.ImagePoint]¶: Vector of input image points.

Returns:

Bounding box of the points.

get_i(self) → float¶

Gets the point coordinate corresponding to the \(i\) axes in the frame (i,j).

Note

See get_j() , get_u() , get_v()

Returns:: The value of the coordinate along the \(i\) axes.

get_j(self) → float¶

Gets the point coordinate corresponding to the \(j\) axes in the frame (i,j).

Note

See get_i() , get_u() , get_v()

Returns:: The value of the coordinate along the \(j\) axes.

get_u(self) → float¶

Gets the point coordinate corresponding to the \(u\) axes in the frame (u,v).

Note

See get_i() , get_j() , get_v()

Returns:: The value of the coordinate along the \(u\) axes.

get_v(self) → float¶

Gets the point coordinate corresponding to the \(v\) axes in the frame (u,v).

Note

See get_i() , get_j() , get_u()

Returns:: The value of the coordinate along the \(v\) axes.

inRectangle(self, rect: visp._visp.core.Rect) → bool¶

Check if an image point belongs to a rectangle.

Parameters:

rect: visp._visp.core.Rect¶: the rectangle.

Returns:

Returns true if the point belongs to the rectangle.

inSegment(self, start: visp._visp.core.ImagePoint, end: visp._visp.core.ImagePoint) → bool¶

Test if the image point belongs to a segment represented by two image points.

To see how to use this function, a code snippet is given in nextInSegment() .

Note

See nextInSegment()

Parameters:

start: visp._visp.core.ImagePoint¶: Segment start image point.
end: visp._visp.core.ImagePoint¶: Segment end image point.

Returns:

True if current image point belongs to the segment. False otherwise.

nextInSegment(self, start: visp._visp.core.ImagePoint, end: visp._visp.core.ImagePoint) → visp._visp.core.ImagePoint¶

Considering current image point, returns the next image point that belongs to the segment [start,end].

The following sample code shows how to use this function to find all the pixels that belong to the segment defined by 2 image points with coordinates [10,12] and [20,16]:

#include <iostream>
#include <visp3/core/vpImagePoint.h>

int main()
{
  vpImagePoint start_pixel(10, 12);
  vpImagePoint end_pixel(20, 16);

  for (auto curr_pixel = start_pixel; curr_pixel.inSegment(start_pixel, end_pixel);
    curr_pixel = curr_pixel.nextInSegment(start_pixel, end_pixel)) {
    std::cout << "pixel: " << curr_pixel << std::endl;
    if (curr_pixel == end_pixel) break;
  }

  return EXIT_SUCCESS;
}

It produces the following output by printing all the pixels belonging to the segment:

pixel: 10, 12
pixel: 11, 12.4
pixel: 12, 12.8
pixel: 13, 13.2
pixel: 14, 13.6
pixel: 15, 14
pixel: 16, 14.4
pixel: 17, 14.8
pixel: 18, 15.2
pixel: 19, 15.6
pixel: 20, 16

Note

See inSegment()

Parameters:

start: visp._visp.core.ImagePoint¶: Segment start image point.
end: visp._visp.core.ImagePoint¶: Segment end image point.

Returns:

Regarding current image point, next image point that belongs to the liSegmentne [start,end].

set_i(self, ii: float) → None¶

Sets the point coordinate corresponding to the \(i\) axes in the frame (i,j).

Note

See set_j() , set_u() , set_v()

Parameters:

ii: float¶: The desired value for the coordinate along the \(i\) axes.

set_ij(self, ii: float, jj: float) → None¶

Sets the point coordinates in the frame (i,j).

Note

See set_i() , set_j() , set_u() , set_v()

Parameters:

ii: float¶: The desired value for the coordinate along the \(i\) axes.
jj: float¶: The desired value for the coordinate along the \(j\) axes.

set_j(self, jj: float) → None¶

Sets the point coordinate corresponding to the \(j\) axes in the frame (i,j).

Note

See set_i() , set_u() , set_v()

Parameters:

jj: float¶: The desired value for the coordinate along the \(j\) axes.

set_u(self, u: float) → None¶

Sets the point coordinate corresponding to the \(u\) axes in the frame (u,v).

Note

See set_i() , set_j() , set_v()

Parameters:

u: float¶: The desired value for the coordinate along the \(u\) axes.

set_uv(self, u: float, v: float) → None¶

Sets the point coordinates in the frame (u,v).

Note

See set_i() , set_j() , set_u() , set_v()

Parameters:

u: float¶: The desired value for the coordinate along the \(u\) axes.
v: float¶: The desired value for the coordinate along the \(v\) axes.

set_v(self, v: float) → None¶

Sets the point coordinate corresponding to the \(v\) axes in the frame (u,v).

Note

See set_i() , set_j() , set_u()

Parameters:

v: float¶: The desired value for the coordinate along the \(v\) axes.

static sqrDistance(iP1: visp._visp.core.ImagePoint, iP2: visp._visp.core.ImagePoint) → float¶

Compute the distance \(|iP1 - iP2| = (i_1-i_2)^2+(j_1-j_2)^2\)

Parameters:

iP1: visp._visp.core.ImagePoint¶: First point
iP2: visp._visp.core.ImagePoint¶: Second point

Returns:

the distance between the two points.