Define seed points for (all) neurons within a region of interest

[jefferis]

• ideally would have nice evenly spaced point locations as output
• could do this by "throwing darts" at the location and using flywire_xyz2id()
• this is pretty fast (hundreds per second) but doing this exhaustively might still be expensive.
• could perhaps do it exhaustively by fetching all of the supervoxels within the roi by fetching the segmentation image itself
  • then making sure that we have at least one xyz location for each supervoxel id.
• there might be efficient ways to use e.g. a 2D voronoi diagram to get nice evenly spaced points

[jefferis]

The ROI might be defined by a series of connected points (like this).