imshow and plot not displaying when using opticalFlow

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Paul Gresham
Paul Gresham 2016-3-19
回答： Issa Al-Hmoud 2019-8-20
Hi, Following the optical flow examples, the code below is behaving in an odd way. If I only use imshow on the image it will refresh in real-time (i.e comment out the plot command), however if I try to plot the optical flow vectors, I will only get the very last frame displayed once the loop has completed. Could anyone shed any light on this?
vidDevice = imaq.VideoDevice('winvideo', 1);
optical = opticalFlowHS;
nFrames = 0;
while (nFrames<100)
nFrames = nFrames + 1;
rgbData = step(vidDevice);
grey = rgb2gray(rgbData);
optFlow = estimateFlow(optical,grey);
imshow(rgbData);
hold on
plot(optFlow, 'DecimationFactor',[5 5],'ScaleFactor',25);
hold off
end
release(vidDevice);
Many thanks

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采纳的回答

Jan
Jan 2016-3-19
Try to insert a drawnow command to allow Matlab to update the display.
It will be faster to create the axes and image objects once before the loop and update the 'CData' property inside the loop only.

更多回答（1 个）

Issa Al-Hmoud
Issa Al-Hmoud 2019-8-20
try the pause command after the hold off
pause(0.1)

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