measuring issue with imageJ

Posted by mizuki on
URL: http://imagej.273.s1.nabble.com/measuring-issue-with-imageJ-tp3683377.html

For my research i have to measure snails(physa acuta) , i've measured them both with a caliper and imageJ, imageJ does not give me the proper measurements, i think it could be because of the concave nature of the shell. Does anyone know a way to accurately measure concave structures?