Main Content

cameraIntrinsicsToOpenCV

Convert camera intrinsic parameters from MATLAB to OpenCV

Since R2021b

collapse all in page

Syntax

[intrinsicMatrix,distortionCoefficients] = cameraIntrinsicsToOpenCV(intrinsics)

Description

[intrinsicMatrix,distortionCoefficients] = cameraIntrinsicsToOpenCV(intrinsics) converts a MATLAB® cameraIntrinsics or cameraParameters object, specified by intrinsics, to OpenCV camera intrinsic parameters.

The OpenCV spatial coordinate system specifies the upper-left pixel center at (0,0), whereas the MATLAB spatial coordinate system specifies the pixel center at (1,1). The cameraIntrinsicsToOpenCV function compensates for this difference by subtracting 1 from both the x and y-values for the converted principal point.

OpenCV camera intrinsic parameters do not include the skew of a pinhole camera model. Therefore, only the intrinsics that were estimated without the skew can be exported to OpenCV.

example

Examples

collapse all

Open Live Script

Create a set of calibration images.

images = imageDatastore(fullfile(toolboxdir('vision'),'visiondata', ...
                        'calibration','mono'));
imageFileNames = images.Files;

Detect the checkerboard calibration pattern in the images.

[imagePoints,boardSize] = detectCheckerboardPoints(imageFileNames);

Generate the world coordinates of the corners of the squares. Square size is in millimeters.

squareSize = 29;
worldPoints = patternWorldPoints('checkerboard',boardSize,squareSize);

Calibrate the camera.

I = readimage(images,1); 
imageSize = [size(I,1),size(I,2)];
params = estimateCameraParameters(imagePoints,worldPoints, ...
                                  ImageSize=imageSize);

Convert the intrinsic parameters to OpenCV format

[intrinsicMatrix,distortionCoefficients] = cameraIntrinsicsToOpenCV(params);

Input Arguments

collapse all

Camera intrinsic parameters, specified as a cameraIntrinsics or a cameraParameters object.

Output Arguments

collapse all

Camera intrinsics matrix formatted for OpenCV, returned as a 3-by-3 matrix of the form:

[fx0cx0fycy001]

where fx and fy are the focal lengths in the x and y-directions, and (cx,cy) is the principal point in OpenCV.

Camera radial and tangential distortion coefficients, returned as a five-element vector in the form [k1 k2 p1 p2 k3]. The values of k1, k2, and k3 describe the radial distortion and p1 and p2 describe the tangential distortion, specified in OpenCV.

Version History

Introduced in R2021b

See Also

Apps

Objects

Functions