Adjust regionprops orientation in order to get 360 degree value.

I have a point at an end of an ellipse that I am considering the 'head' and I want to get the "orientation" of this ellipse from 0-360 degrees with the head point facing directly up as 0 degrees. I understand that the Orientation field in regionprops works on the X axis from 0 to -90 degrees. How can I adjust this information to fit my goal.

[KAE]

Is the ellipse you have in an image? regionprops is for images.

[Matt J]

I want to get the "orientation" of this ellipse from 0-360 degrees

I assume you really mean 0-180.

Answer 1

[Matt J]

theta = 90-Orientation

assuming theta increases clockwise.

[KAE]

The angle definition of regionprops orientation can trip you up. In Matlab all images have the y-axis reversed, so y=0 is at the image top. The angle is defined to be CCW from the x-axis to the shape's main axis, when seen with the y-axis reversed. Just a cautionary note which is not spelled out in the documentation page for regionprops.