cameraIntrinsics

Object for storing intrinsic camera parameters

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Description

Store information about a camera’s intrinsic calibration parameters, including the lens distortion parameters.

Creation

Syntax

intrinsics = cameraIntrinsics(focalLength,principalPoint,imageSize)

intrinsics = cameraIntrinsics(___,Name,Value)

Description

example

intrinsics = cameraIntrinsics(focalLength,principalPoint,imageSize) returns a camera intrinsics object that contains the focal length specified as [fx,fy], and the camera's principal point specified as [cx, cy]. See cameraParameters for more details.

intrinsics = cameraIntrinsics(___,Name,Value) uses additional options specified by one or name-value pairs. Enclose each property name in quotes. For example, intrinsics = cameraIntrinsics('RadialDistortion',[0,0])

Input Arguments

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`focalLength` — Camera focal length
two-element vector

Camera focal length, specified as a two-element vector, [fx, fy].

$f_{x} = F \times s x$

$f_{y} = F \times s y$

F is the focal length in world units, typically millimeters
[sx, sy] are the number of pixels per world unit in the x and y direction respectively
fx and fy are in pixels

`principalPoint` — Optical center of camera
two-element vector

Optical center of camera, specified as a two-element vector, [cx,cy], in pixels.

`imageSize` — Image size produced by the camera
two-element vector

Image size produced by the camera, specified as a two-element vector, [mrows,ncols].

Properties

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`RadialDistortion` — Radial lens distortion
`[0,0]` (default) | two-element vector | three-element vector

Radial lens distortion, specified as the comma-separated pair consisting of RadialDistortion and a two-element vector, [k1,k2], or a three-element vector, [k1,k2,k3]. k1,k2, and k3 are radial distortion coefficients. Radial distortion occurs when light rays bend more near the edges of a lens than they do at its optical center. The smaller the lens, the greater the distortion.

Radial distortion occurs when light rays bend more near the edges of a lens than they do at its optical center. The smaller the lens, the greater the distortion.

The camera parameters object calculates the radial distorted location of a point. You can denote the distorted points as (x_distorted, y_distorted), as follows:

x_distorted = x(1 + k₁*r² + k₂*r⁴ + k₃*r⁶)

(1)

y_distorted= y(1 + k₁*r² + k₂*r⁴ + k₃*r⁶)

(2)

x, y = undistorted pixel locations

k₁, k₂, and k₃ = radial distortion coefficients of the lens

r² = x² + y²

Typically, two coefficients are sufficient. For severe distortion, you can include k₃. The undistorted pixel locations appear in normalized image coordinates, with the origin at the optical center. The coordinates are expressed in world units.

`TangentialDistortion` — Tangential distortion coefficients
`[0,0]` (default) | two-element vector

Tangential distortion coefficients, specified as the comma-separated pair consisting of 'TangentialDistortion' and a 2-element vector, [p₁,p₂]. Tangential distortion occurs when the lens and the image plane are not parallel.

The camera parameters object calculates the tangential distorted location of a point. You can denote the distorted points as (x_distorted, y_distorted), as follows:

x_distorted = x + [2 * p₁ * x * y + p₂ * (r² + 2 * x²)]

(3)

y_distorted = y + [p₁ * (r² + 2*y²) + 2 * p₂ * x * y]

(4)

x, y = undistorted pixel locations

p₁ and p₂ = tangential distortion coefficients of the lens

r² = x² + y²

The undistorted pixel locations appear in normalized image coordinates, with the origin at the optical center. The coordinates are expressed in world units.

`Skew` — Camera axes skew
`0` (default) | angle

Camera axes skew, specified as the comma-separated pair consisting of 'skew' and an angle. If the x and the y axes are exactly perpendicular, then the skew must be 0.

`FocalLength` — Focal length
2-element vector

This property is read-only.

Focal length in x and y, stored as a 2-element vector [fx, fy] in pixels.

fx = F * sx

fy = F * sy

F is the focal length in world units, typically in millimeters, and [sx, sy] are the number of pixels per world unit in the x and y direction respectively. Thus, fx and fy are in pixels.

The focal length F influences the angle of view and thus affects the area of the scene that appears focused in an image. For a fixed subject distance:

A short focal length offers a wide angle of view allowing to capture large area of the scene under focus. It emphasizes both the subject and the scene background.
A long focal length offers a narrow angle of view, thus reducing the area of the scene under focus. It emphasizes more on the subject and restricts the amount of background from being captured.

`PrincipalPoint` — Optical center of camera
two-element vector

This property is read-only.

Optical center of camera, stored as a two-element vector [cx,cy] in pixels. The vector contains the coordinates of the optical center of the camera.

`ImageSize` — Image size produced by the camera
two-element vector

This property is read-only.

Image size produced by the camera, stored as a two-element vector, [mrows,ncols].

`IntrinsicMatrix` — Projection matrix
3-by-3 identity matrix (default) | 3-by-3 intrinsic matrix

This property is read-only.

Projection matrix, stored as the comma-separated pair consisting of 'IntrinsicMatrix' and a 3-by-3 matrix. For the matrix format, the object uses the following format:

$[\begin{matrix} f_{x} & 0 & 0 \\ s & f_{y} & 0 \\ c_{x} & c_{y} & 1 \end{matrix}]$

The coordinates [c_x c_y] represent the optical center (the principal point), in pixels. When the x and y axis are exactly perpendicular, the skew parameter, s, equals 0.

f_x = F*s_x

f_y = F*s_y

F, is the focal length in world units, typically expressed in millimeters.

[s_x, s_y] are the number of pixels per world unit in the x and y direction respectively.

f_x and f_y are expressed in pixels.

Examples

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Create an Object Containing Fundamental Camera Parameters

Open Live Script

Define camera parameters without lens distortion or skew.

Specify the focal length and principal point in pixels.

    focalLength    = [800, 800]; 
    principalPoint = [320, 240];
    imageSize      = [480, 640];

Create a camera intrinsics object.

intrinsics = cameraIntrinsics(focalLength,principalPoint,imageSize)

intrinsics = 
  cameraIntrinsics with properties:

             FocalLength: [800 800]
          PrincipalPoint: [320 240]
               ImageSize: [480 640]
        RadialDistortion: [0 0]
    TangentialDistortion: [0 0]
                    Skew: 0
         IntrinsicMatrix: [3x3 double]

Documentation

cameraIntrinsics

Description

Creation

Syntax

Description

Input Arguments

`focalLength` — Camera focal length
two-element vector

`principalPoint` — Optical center of camera
two-element vector

`imageSize` — Image size produced by the camera
two-element vector

Properties

`RadialDistortion` — Radial lens distortion
`[0,0]` (default) | two-element vector | three-element vector

`TangentialDistortion` — Tangential distortion coefficients
`[0,0]` (default) | two-element vector

`Skew` — Camera axes skew
`0` (default) | angle

`FocalLength` — Focal length
2-element vector

`PrincipalPoint` — Optical center of camera
two-element vector

`ImageSize` — Image size produced by the camera
two-element vector

`IntrinsicMatrix` — Projection matrix
3-by-3 identity matrix (default) | 3-by-3 intrinsic matrix

Examples

Create an Object Containing Fundamental Camera Parameters

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

See Also

Topics

Computer Vision Toolbox Documentation

Support

Documentation

cameraIntrinsics

Description

Creation

Syntax

Description

Input Arguments

focalLength — Camera focal length two-element vector

principalPoint — Optical center of camera two-element vector

imageSize — Image size produced by the camera two-element vector

Properties

RadialDistortion — Radial lens distortion [0,0] (default) | two-element vector | three-element vector

TangentialDistortion — Tangential distortion coefficients [0,0] (default) | two-element vector

Skew — Camera axes skew 0 (default) | angle

FocalLength — Focal length 2-element vector

PrincipalPoint — Optical center of camera two-element vector

ImageSize — Image size produced by the camera two-element vector

IntrinsicMatrix — Projection matrix 3-by-3 identity matrix (default) | 3-by-3 intrinsic matrix

Examples

Create an Object Containing Fundamental Camera Parameters

Extended Capabilities

C/C++ Code Generation Generate C and C++ code using MATLAB® Coder™.

See Also

Topics

Computer Vision Toolbox Documentation

Support

`focalLength` — Camera focal length
two-element vector

`principalPoint` — Optical center of camera
two-element vector

`imageSize` — Image size produced by the camera
two-element vector

`RadialDistortion` — Radial lens distortion
`[0,0]` (default) | two-element vector | three-element vector

`TangentialDistortion` — Tangential distortion coefficients
`[0,0]` (default) | two-element vector

`Skew` — Camera axes skew
`0` (default) | angle

`FocalLength` — Focal length
2-element vector

`PrincipalPoint` — Optical center of camera
two-element vector

`ImageSize` — Image size produced by the camera
two-element vector

`IntrinsicMatrix` — Projection matrix
3-by-3 identity matrix (default) | 3-by-3 intrinsic matrix

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.