What do the arrows depict in the optical-flow visualizations such as the one below?

enter image description here

(image source: learnopencv)

Is it correct to say that the pixel at the tip of an arrow was at the origin of the arrow in previous frame?

  • $\begingroup$ It depends! What you say is correct for live / real-time video. But if you're post-processing pre-recorded video then you have all the frames including those at $t+1$. $\endgroup$
    – Peter K.
    Nov 2, 2021 at 17:45
  • $\begingroup$ @PeterK. I have modified the question. $\endgroup$
    – orbit
    Jan 24, 2022 at 8:23

1 Answer 1


Yes, as your linked page shows:

Image from linked page showing displacement

the idea is that the pixels move from $(x,y)$ in the first from to $(x+\Delta x, y + \Delta y)$ in the second. I believe the image you quote is just connecting a series of $(x_i,y_i)$ with their next locations $(x_i+\Delta x_i, y_i + \Delta y_i).$


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