How I can get optical flow from sequential frames?( the number of frames is 180)

Question

hatefe soleymany 2022-5-17

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1721095-how-i-can-get-optical-flow-from-sequential-frames-the-number-of-frames-is-180

回答： hatefe soleymany 2022-5-24

Hi everyone, I have a question about image processing, I have a clip from dataset ped2. I want to get optical flow from this clip. But in my clip there are all of frames and I dont want to use film from, in fact my inputs are sequntional frames that their formats are '.png'.

please help me...

How I can get optical flow from this sequentioal images?

(the number of frames is 180)

I got to know with several algorithm for optical flow, for example opticalFlowLKDoG, opticalFlowLK and opticalFlowHS, I know how I can use from those algorithm for get optical flow for a film but for a sequentioal frames I dont know....

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Answer 1

hatefe soleymany 2022-5-24

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1721095-how-i-can-get-optical-flow-from-sequential-frames-the-number-of-frames-is-180#answer_970640

在 MATLAB Online 中打开

I could write it answer.

We can use this cod:

for clip=1:16
    clipsize= [10 150 150 180 180 150 150 120 180 180 180 180 180 150 150 150];
    for i=10:clipsize(clip)
        
        L1=imread(['outfile\test' int2str(clip) '\new_img' num2str(i-1) '.png']);
        L2=imread(['ourfile\test' int2str(clip) '\new_img' num2str(i) '.png']);
        ww = 40;
w = round(ww/2);
% Reduce the size of the image
sc = 2;
im2c = imresize(L2, 1/sc);
C1 = corner(im2c);
C1 = C1*sc;
    
% Discard coners near the margin of the image
k = 1;
for iI1 = 1:size(C1,1)
    x_i = C1(iI1, 2);
    y_i = C1(iI1, 1);
    if x_i-w>=1 && y_i-w>=1 && x_i+w<=size(L1,1)-1 && y_i+w<=size(L1,2)-1
      C(k,:) = C1(iI1,:);
      k = k+1;
    end
end
Ix_m = conv2(L1,[-1 1; -1 1], 'valid'); % partial on x
Iy_m = conv2(L1, [-1 -1; 1 1], 'valid'); % partial on y
It_m = conv2(L1, ones(2), 'valid') + conv2(L2, -ones(2), 'valid'); % partial on t
u = zeros(round(length(C)./3),1);
v = zeros(round(length(C)./2),1);
% within window ww * ww
for k = 1:length(C(:,2))
    iI1 = C(k,2);
    j = C(k,1);
      Ix = Ix_m(iI1-w:iI1+w, j-w:j+w);
      Iy = Iy_m(iI1-w:iI1+w, j-w:j+w);
      It = It_m(iI1-w:iI1+w, j-w:j+w);
      Ix = Ix(:);
      Iy = Iy(:);
      b = -It(:); % get b here
      A = [Ix Iy]; % get A here
      nu = pinv(A)*b;
      u(k)=nu(1);
      v(k)=nu(2);
end
figure();
imshow(L2);
hold on;
quiver(C(:,1), C(:,2), u,v, 1,'r')
    end
end