measuring angles with straight line tool

Posted by Jordan Mallon on Apr 06, 2009; 1:08am
URL: http://imagej.273.s1.nabble.com/measuring-angles-with-straight-line-tool-tp3693087.html

I use the straight line tool in ImageJ quite regularly to measure
angles. I am frustrated, though, that I cannot control the baseline
from which to measure the angles. A straight line drawn towards the
right (i.e., 3 o'clock) yields 0 degrees; a line drawn upwards (12
o'clock) yields 90 degrees; a line to the left ( 9 o'clock) yields 180
degrees; and a line drawn downwards (6 o'clock) yields -90 degrees. Is
there an easy way to change the settings in ImageJ so that I can set
the 0 degree baseline, say, at 12 o'clock? And is it possible to
adjust the scale of measurement to yield positive angles only (so
that, say, -90 = 270 degrees)?
Thanks,

Jordan