worldToImage

Project world points into image

Description

example

imagePoints = worldToImage(cameraParams,rotationMatrix,translationVector,worldPoints) returns the projection of 3-D world points into an image given camera parameters, the rotation matrix, and the translation vector.

imagePoints = worldToImage(___'ApplyDistortion',distort) returns the projection with the option of applying distortion. This syntax is supported for nonfisheye camera parameters.

Examples

collapse all

Create a set of calibration images.

images = imageDatastore(fullfile(toolboxdir('vision'),'visiondata', ...
      'calibration','slr'));

Detect the checkerboard corners in the images.

[imagePoints,boardSize] = detectCheckerboardPoints(images.Files);

Generate the world coordinates of the checkerboard corners in the pattern-centric coordinate system, with the upper-left corner at (0,0).

squareSize = 29; % in millimeters
worldPoints = generateCheckerboardPoints(boardSize,squareSize);

Calibrate the camera.

cameraParams = estimateCameraParameters(imagePoints,worldPoints);

Load the image at a new location.

imOrig = imread(fullfile(matlabroot,'toolbox','vision','visiondata', ...
        'calibration','slr','image9.jpg'));

imshow(imOrig,'InitialMagnification',30);

Undistort the image.

imUndistorted = undistortImage(imOrig,cameraParams);

Find a reference object in the new image.

[imagePoints,boardSize] = detectCheckerboardPoints(imUndistorted);

Compute new extrinsics.

[R,t] = extrinsics(imagePoints,worldPoints,cameraParams);

Add a z-coordinate to the world points.

zCoord = zeros(size(worldPoints,1),1);
worldPoints = [worldPoints zCoord];

Project the world points back into the original image.

projectedPoints = worldToImage(cameraParams,R,t,worldPoints);
hold on
plot(projectedPoints(:,1),projectedPoints(:,2),'g*-');
legend('Projected points');
hold off

Input Arguments

collapse all

Camera parameters, specified as a cameraParameters or fisheyeParameters object. These objects contain the intrinsic, extrinsic, and lens distortion parameters of a camera.

3-D rotation of the world coordinates relative to the image coordinates, specified as a 3-by-3 matrix. The rotation matrix, together with the translation vector, enable you to transform points from the world coordinate system to the camera coordinate system. The rotationMatrix and translationVector inputs must be the same data type.

Data Types: double | single

3-D translation of the world coordinates relative to the image coordinates, specified as a 1-by-3 vector. The translation vector, together with the rotation matrix, enable you to transform points from the world coordinate system to the camera coordinate system. The rotationMatrix and translationVector inputs must be the same data type.

Data Types: double | single

3-D world points, specified as an M-by-3 matrix containing M [x,y,z] coordinates of 3-D world points.

Option to apply lens distortion, specified as false or true. When you set this argument to true, the function applies lens distortion to the output imagePoints.

This argument is valid only when using a cameraParameters object as the cameraParams input.

Output Arguments

collapse all

Image points, returned as an M-by-2 matrix of M [x,y] point coordinates.

Introduced in R2016b