Image Mosaicing in MAtlab using SIFT and RANSAC

Question

Sean 2014-9-8

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/153996-image-mosaicing-in-matlab-using-sift-and-ransac

回答： Soso 2015-7-1

The following is a piece of code that forms a Mosaic of two images after computing the Homography Matrix H using RANSAC pror to which SIFT was used to compute the descriptors:

    % --------------------------------------------------------------------
    %                                                               Mosaic
    % --------------------------------------------------------------------
    box2 = [1  size(im2,2) size(im2,2)  1 ;
            1  1           size(im2,1)  size(im2,1) ;
            1  1           1            1 ] ;
    box2_ = inv(H) * box2 ;
    box2_(1,:) = box2_(1,:) ./ box2_(3,:) ;
    box2_(2,:) = box2_(2,:) ./ box2_(3,:) ;
    ur = min([1 box2_(1,:)]):max([size(im1,2) box2_(1,:)]) ;
    vr = min([1 box2_(2,:)]):max([size(im1,1) box2_(2,:)]) ;
    [u,v] = meshgrid(ur,vr) ;
    im1_ = vl_imwbackward(im2double(im1),u,v) ;
    z_ = H(3,1) * u + H(3,2) * v + H(3,3) ;
    u_ = (H(1,1) * u + H(1,2) * v + H(1,3)) ./ z_ ;
    v_ = (H(2,1) * u + H(2,2) * v + H(2,3)) ./ z_ ;
    im2_ = vl_imwbackward(im2double(im2),u_,v_) ;
    mass = ~isnan(im1_) + ~isnan(im2_) ;
    im1_(isnan(im1_)) = 0 ;
    im2_(isnan(im2_)) = 0 ;
    mosaic = (im1_ + im2_) ./ mass ;
    figure(2) ; clf ;
    imagesc(mosaic) ; axis image off ;
    title('Mosaic') ;
    if nargout == 0, clear mosaic ; end
    end

I understand box2 is an area that's created based on the size of our second image in which the images will be stitcked. Why then, are we performing an Inverse Homography multiplication on it?

Could someone please explain the steps that follow as I'm not familiar with image mosaicing in Matlab.

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Sean 2014-9-8

For those looking for the complete code, it's available here:

http://www.vlfeat.org/applications/sift-mosaic-code.html

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

khadija laaroussi 2014-11-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/153996-image-mosaicing-in-matlab-using-sift-and-ransac#answer_160326

can you see this project: https://sites.google.com/site/computervisionadinastoica/project-2-image-mosaicing-workflow

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 2

Soso 2015-7-1

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/153996-image-mosaicing-in-matlab-using-sift-and-ransac#answer_184629

Hi Sean;

Did you get how this piece of code works? I am struggling to understand this code. Could you or someone explain to me how this works, please? Thank you in advance.