Hough Transform Angles ... trouble visualizing them

I’m using img.find_line_segments() to find lines within a particular ROI.
I’m able to return lines, the length, theta, roi, etc.

I’m having a little trouble visualizing in my head the line drawn from img.draw_line() and the corresponding theta value shown when printing the line.
Within the documentation, it says that theta has a range of (0,179) … but in relation to what?
I understand that the end points will be used, but where’s the origin? Is this the inner-angle? (does that make sense?)
Thank you.

See the latest blog post of the main website. I posted a nice wrote up on this. Theta is measurered in comolexish way. The write up covers this.