Question

我无法理解Matlab如何使用 当前帧来通过光流计算视频帧的速度矩阵。速度不会是一个不同像素位置的关系，在时间变化，包括每帧两帧或更多帧的分析？

http://www.mathworks.com/help/imaq/examples/live-motion-detection-using-optical-flow.html?requestedDomain=www.mathworks.com

http://www.mathworks.com/help/vision/ref/vision.opticalflow-class.html

% Set up for stream
nFrames = 0;
while (nFrames<100)     % Process for the first 100 frames.
    % Acquire single frame from imaging device.
    rgbData = step(vidDevice);

    % Compute the optical flow for that particular frame.
    optFlow = step(optical,rgb2gray(rgbData)); %***HERE IS THE DOUBT! iT JUST USES ONE FRAME!!!***

    % Downsample optical flow field.
    optFlow_DS = optFlow(r, c);
    H = imag(optFlow_DS)*50;
    V = real(optFlow_DS)*50;

    % Draw lines on top of image
    lines = [Y(:)'; X(:)'; Y(:)'+V(:)'; X(:)'+H(:)'];
    rgb_Out = step(shapes, rgbData,  lines');

    % Send image data to video player
    % Display original video.
    step(hVideoIn, rgbData);
    % Display video along with motion vectors.
    step(hVideoOut, rgb_Out);

    % Increment frame count
    nFrames = nFrames + 1;
end

Answer 1

vision.OpticalFlow是一个班级。当您创建vision.OpticalFlow对象并调用其step方法时，它会记住您传递给它的帧。然后在每次对step的调用中，它计算最后一次调用的存储帧与当前帧之间的光流。

顺便说一下，vision.OpticalFlow已被弃用。如果您有最新版本的MATLAB，则可以使用一系列光流功能：opticalFlowFarneback，opticalFlowHS，opticalFlowLK和opticalFlowLKDoG。

计算视频帧中对象的速度 - 光流（Matlab）

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