“…Therefore it may need to be agglomerated with other connected components (heuristically [17,18,26] or based on learned weights of handcrafted features [2,27,40,41]), but it should not be broken down into smaller segments. Numerous 3-D reconstruction systems follow this bottom-up design [6,7,27,31,35,40,41,44]. A heavily engineered implementation of hierarchical segmentation [31] still occupies the leading entry in the (still active) classical SNEMI3D connectomics contest of 2013 [5], evaluated in terms of the uniform instance segmentation correctness metrics (normalized Rand-Error [53] and Variation of Information [36]).…”