i'm trying unwrapp cylinder on picture in matlab, need red markers , yellow threads (see picture attached) on 2d-plane in line. have tried few approaches "imtransform" doesn't seem work.
i thinking of adding grid on cylinder know how adjust transformation.
did have same problem? happy ideas of how solve problem.
strictly speaking, cannot done
the imtransform can allow images rectified through projective transform, assumes objects in image lie on planar surface. taking picture of chessboard 2 different angles. see image below.
the reason chessboard can rectified because planar. because cylinder 3d, cannot rectify points.
what can instead
it possible extract subimages cylinder, rectify each subimage, stitch them together.
example
first, subimages selecting points inbetween red dots (shown red o's on image). note bottom 1 arbitrary. then, pick places want red dots end shown (green x's). 
next, rectify each subimage. note red dots lie on green x's.
first sub image
second sub-image
third sub-image
now stitch image together. note now, red dots lie on same line.
close all; clear all; clc; %read image im1 = imread('crctbm.jpg'); %location of red dots x1 = [49; 106; 178; 234]; y1 = [115 116 126 136]; %red dots aligned on yline in final image yline = y1(1); %initialize cells subim = cell(1,length(x1)-1); %tracks parsed images transform = cell(1,length(x1)-1); %projective transform each subim rectifiedim = cell(1,length(x1)-1); %rectified images %initialize boundaries of image (due warping, images can %stretch beyond border of original image) xdataout = [1,1]; ydataout = [1,1]; t1 = figure; imshow(im1); ii = 1:length(x1)-1 %extract subimage defined red dots tim = zeros(size(im1)); tim(:,x1(ii):x1(ii+1),:) = im1(:,x1(ii):x1(ii+1),:); subim{ii} = tim; %define 4 points in original image originalpoints{ii} = [x1(ii),y1(ii);... %red dot x1(ii+1),y1(ii+1);... %red dot x1(ii),y1(ii)+50;... %arbitrary point x1(ii+1),y1(ii)+50]; %arbitrary point %define there 4 points should lie in rectified image correctedpoints{ii} = [x1(ii),yline;... %red dot should stay on same x-coordinate, y-coordinate shited yline x1(ii+1),yline;... %red dot should stay on same x-coordinate, y-coordinate shited yline x1(ii),yline+50;... %rectilinear point x1(ii+1),yline+50]; %rectilinear point %plot original , corrected coordinates on image figure(t1); hold on; plot(originalpoints{ii}(:,1),originalpoints{ii}(:,2),'ro'); plot(correctedpoints{ii}(:,1),correctedpoints{ii}(:,2),'gx'); legend('original points','correctedpoints{ii}'); %sometimes rectified image extends beyond borders of %original boundary. finds worst case scenario warping , %sets boundaries transform{ii} = maketform('projective',originalpoints{ii},correctedpoints{ii}); [~,xdataim2t,ydataim2t]=imtransform(im1,transform{ii}); % xdataim2t , ydataim2t store bounds of transformed im2 xdataout=[min([1,xdataim2t(1),xdataout(1)]) max([size(im1,2),xdataim2t(2),xdataout(2)])]; ydataout=[min([1,ydataim2t(1),xdataout(1)]) max([size(im1,1),ydataim2t(2),xdataout(2)])]; end %rectify images rectifiedx = floor(xdataout(1)):ceil(xdataout(2))+1; %x-coordinates of new image rectifiedy = floor(ydataout(1)):ceil(ydataout(2))+1; %y-coordinates of new image ii = 1:length(x1)-1 rectifiedim{ii}=imtransform(subim{ii},transform{ii},'xdata',xdataout,'ydata',ydataout); figure; image(rectifiedx,rectifiedy,uint8(rectifiedim{ii})); hold on; plot(originalpoints{ii}(:,1),originalpoints{ii}(:,2),'ro'); plot(correctedpoints{ii}(:,1),correctedpoints{ii}(:,2),'gx'); legend('original points','rectified points'); end %stitch subimages finalim = zeros(size(rectifiedim{1})); ii = 1:length(rectifiedim) finalim = max(double(finalim),double(rectifiedim{ii})); end figure; imshow(uint8(finalim)); edit:
if care aligning points in 1d, possible align them along epipolar lines.
Comments
Post a Comment