Extract magnitude from area returns NaN
Laurin Nüesch
Hello,
I am trying to use "Extract parameters from area" in PIVlab.
My understanding is that when I select "Magnitude in m/s" and draw a rectangle, PIVlab should calculate the mean velocity magnitude of all valid vectors located inside that rectangle for the current frame (or for all frames when exporting).
However, I often obtain:
Mean (m/s) = NaNeven though I can clearly see valid vectors inside the selected rectangle and in the currently displayed frame.
My vector field is generally very sparse because the image sequence is difficult to correlate and only a few vectors survive the validation process. In some frames there may be only one or two valid vectors.
Could someone explain how the extraction tool determines which vectors are included in the calculation?
William
Laurin Nüesch
