Coordinate System for mean vector direction (in degrees) over a time

[Minerva Ferrer]

Hello William,

I am relatively new to using PIVlab, so I apologise in advance if my questions are too basic. 

Currently, I am attempting to calculate the mean vector direction (in degrees) over a time series within a circular region of interest. As mentioned in one of the previous conversations, I am finding the output difficult to interpret, and I have not been able to locate the coordinates. I would also like to clarify whether each output is defined relative to a fixed coordinate system or whether it represents a continuous measure relative to the previous time point. This distinction is important for my analysis, as I aim to describe continuous changes over time.

Thank you very much in advance, 

Minerva

[William]

Hi, this will average all velocities in that area over time and over area, and then give you the mean flow direction. The results are in principle like 180 degree is to the left of the image, -180 to the right, 90 up. -90 down. I do not know the exact signs and numbers, but it is like this in principle.

Does this help?

If you are unsure about the effect of some parameters, I would always recommend to generate some synthetic images in Pivlab with known properties, and then test the output.