title: 3D annotation for instance segmentation
body: <p>I'm trying to annotate some data for 3D instance segmentation. While it's fairly straightforward to draw masks for each 2D plane, it's not obvious how to connect the same &quot;instances&quot; together post-annotation (ie. connect the &quot;red&quot; masks together, connect the &quot;blue&quot; masks together) without laboriously making sure the instances are instance-matched (ie. colour-coded to make sure &quot;red&quot; masks always connect with &quot;red&quot; masks).</p>
  <p>A naive approach I have thought of is to make many 2D segmentation masks, and calculate the center of mass for each object detected. I can later re-assign the instances based on the closest matching center of mass, but I worry this would inadvertently generate &quot;crossed-over&quot; segmentation instances (illustrated below). What are some high-throughput strategies to generate 3D annotations?</p>
  <p><a href="https://i.stack.imgur.com/hXkm5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hXkm5.png" alt="enter image description here" /></a></p>