Ask Your Question

Revision history [back]

click to hide/show revision 1
initial version

orientation angle of ellipse

Hello everyone, I am having some trouble in understanding how the angle parameter of the ellipse function actually works. In the documentation it is meant to be anti-clockwise and referring to the main axis. Therefore, for instance, if I try to draw an ellipse of size (100,50) and angle 45 deg I expect it to be in the first quadrant while instead it is in the second.

For instance this:

ellipse(im, Point(im.cols/2, im.rows/2), Size(100, 50), 45, 0, 360, Scalar(200,0,0));

leads to the image below.

Of course if I switch the axis the orientation gets correct but this seems to be in contrast with the image shown in the documentation. (opencv drawing doc)

What am I misunderstanding?

image description