turn image coordinates into world coordinates??

I have a problem and I do not understand how to turn image coordinates into world coordinates. I would really love to help.

Thanks .

this is my code...

% Initialization steps.

clc;

clearvars;

close all;

workspace;

fontSize = 16;

objects = imaqfind; %find video input objects in memory % מחפש את כל קלטי הוידאו שבזכרון

delete(objects) %delete a video input object from memory %מאפס את כל קלטי הוידאו

load('cameraParams1.mat')% נתונים מהקליברציה

focalLength = [cameraParams.FocalLength(1), cameraParams.FocalLength(2)]; % [fx, fy] in pixel units

principalPoint = [cameraParams.PrincipalPoint(1), cameraParams.PrincipalPoint(2)]; % [cx, cy] optical center in pixel coordinates

imageSize = cameraParams.ImageSize; % [nrows, mcols] 480x640

camIntrinsics = cameraIntrinsics(focalLength, principalPoint, imageSize); %מאחסן את הפרמטרים של המצלמה

videoName = 'test3.mp4';

videoReader = VideoReader(videoName);

timeStamp = 0.06667; % time from the beginning of the video

videoReader.CurrentTime = timeStamp; % point to the chosen frame

frame = readFrame(videoReader); % read frame at timeStamp seconds

imshow(frame) % display frame

% fullFileName = 'https://ww2.mathworks.cn/matlabcentral/answers/uploaded_files/988570/road.png';

grayImage = rgb2gray(frame);

figure

imshow(grayImage)

grayImage(grayImage<170)=0;

figure

imshow(grayImage, []);

%impixelinfo;

mask = logical(grayImage > 140 & grayImage < 255);

mask = bwareafilt(mask, 2);

mask = bwskel(mask);

mask2 = imopen(mask, strel('line', 3, 0));

mask(mask2) = 0;

mask = logical(mask);

figure

imshow(mask);

% make center line

[r,c] = find(mask);

rs = sort(unique(r));

cens = [];

for i = 1 : length(rs)

mi = mask(rs(i),:);

[~,ci] = find(mi);

if max(ci) - min(ci) < 1e1

continue;

end

cens = [cens; mean([max(ci) min(ci)]) rs(i)];

end

% make line

p = polyfit(cens(:,2), cens(:,1), 2);

yt = linspace(min(rs), max(rs), 1e3);

xt = polyval(p, yt);

hold on; plot(xt, yt, 'g-', 'LineWidth',3)

figure; imshow(frame);

hold on; plot(xt, yt, 'g-', 'LineWidth',3)

image3D = cat(3, slice1, slice2, slice3, slice4, slice5);

for slice = 1 : totalNumberOfSlices

thisSlice = GetSlice(mask); % Whatever you have to do to get one 2D image.

if slice == 1

image3D = thisSlice;

else

image3D = cat(3, image3D, thisSlice);

end

end

Answer 1

[Sai Pavan]

Hi Yoram,

I understand that you want to convert the image coordinates into world coordinates. The 'img2world2d' function can help you with the conversion as the translation and rotation variables are available in the 'PatternExtrinsics' variable of 'cameraParams1.mat' file as rigidtform3d objects. The 'Instrinsics' variable in the 'cameraParams1.mat' can be used along with the rigid transformations to make this conversion as shown in the code snippet shown below:

worldPoints = img2world2d(imagePoints,tform,intrinsics)

Please refer to the below documentation to learn more about 'img2world2d' function: https://www.mathworks.com/help/vision/ref/img2world2d.html

Hope it helps.

Regards,

Sai Pavan