Quiver plot appears upside down.

Hello,

I'm trying to verify a PIV analysis method but first came across an issue with the quiver command. As seen from the first two attached images, the sense is such that there is no data on the upper left corner triangle. However, the quiver plot displays this data gap in the bottom left corner.

I'm using quiver(u,v), as I don't have x,y data. Does anyone have any suggestions please?

Thank you very much!

Answer 1

[Dave B]

Images are normally shown in what's called ij coordinates, meaning (in the all positive number case) the top left corner is 0,0, but quiver defaults to xy co-ordinates meaning (in the all positive number case) the bottom left corner is 0,0

Fortunately, MATLAB makes it easy to switch, just do:

axis ij

after making your quiver. Alternatively, you could do:

set(gca,'YDir','reverse')

which is what axis ij does.

[Kyle McKinlay]

Thank you very much for your help and quick reply! :)