Question

我想在电影中移动的粒子周围添加一个圆圈。我给每个帧的粒子坐标（变量Traj）。但是，以下代码仅在每个帧的粒子上绘制一个实心矩形。有什么建议吗？

function movie = AurelieCreateMovie3(Filename, Traj)
    L = 369;
    color = [1:3];
    R = 7;
    info = imfinfo(Filename);
    W = info.Width;
    H = info.Height;

    movie = uint8(zeros(H,W,3,L)); 

    frame = Traj(:,1); 
    x = round(Traj(:,2));
    y = round(Traj(:,3));
    L = length(x); %length of this track
    dt = 0:0.01:2*pi;

    for k = 1:L
        movie(:,:,:,k) = imread(Filename,frame(k));    
        x_circle = R.* cos(dt) + x(k);
        y_circle = R.* sin(dt) + y(k);
        movie(round(y_circle), round(x_circle), color, k) = 255;
    end

    mov = immovie(movie);
    movie2avi(mov, 'moviefinal', 'compression', 'None', 'fps', 23);
    implay(mov);
end

Answer 1

当使用matrix(rows, columns) = value分配值时，MATLAB会为rows和columns中的元素分配每个排列，而不是仅指定成对的组合二。相反，您希望使用sub2ind

转换为线性索引

M = reshape(movie(:,:,:,k), [], size(movie, 3));
inds = sub2ind(size(M(:,:)), round(y_circle), round(x_circle));
M(inds,:) = 255;
movie(:,:,:,k) = M;

Matlab - 为电影的每一帧添加圆圈

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