I have recently posted on this Forum a few questions on the use of ImageJ/Fiji to obtain a correct rigid rod length distribution values in cases when some/many rod segments are touching (forming a T or V) or are overlaid (forming an X object.) I have been in touch, and very much helped, by several expert ImageJ users and contributors. However, having tried all the suggested processing methods, plugins and custom-written solutions, I believe that the problem remains fundamentally unresolved (BTW, there’s a recent paper (doi: 10.1088/0957-0233/26/12/125601) in which a very similar problem was studied, but this was done outside of the ImageJ system and the refinements are still in progress. Importantly, only the rod/fiber width was considered, but not their end-to-end length.
A bit out of desperation, and because of my conviction that this image segmentation and analysis problem may be of general interest and importance, I’ve decided to issue the Great Overlaid Rigid-Rod Segmentation and Analysis Challenge (GORRSAC ) to find a reliable and general ImageJ processing pipeline that would recognize that the attached image includes only 7 lines and provide their individual length correctly. None of the solutions I’ve tried so far give (in my non-expert hands) a correct answer (7 lines.) I realize there’s quandary in trying to decide if the crossing point is an end of a segment or if the object continues across it. The general assumption should be that if two segments are on the opposite sides of the crossing and each lies on the line extrapolated from the other, they belong to the same object.
I’m looking forward to your comments, suggestions–and a solution to this challenge! Perhaps some of my correspondents would like to join a group effort as their ideas could contribute to a generally satisfactory solution?