Voronoi Topology Artifacts with topojson merge

[emeeks]

Not sure if it's voronoi.topology or topojson.merge, but you can see some issues with the following implementation:

http://bl.ocks.org/emeeks/75f50585460ad842cd27

This code was derived from code for generating regions in <orbis.stanford.edu/v2/> where it's used for the Regions functionality. To reproduce the behavior there, you need to:
Click the Network tab
Click "calculate network"
Click "Regions" on the right
Click the "+" and "-" buttons on the legend to adjust the break points from which the voronoi is constructed and merged

I realize that's cumbersome but it does demonstrate that the artifacts are different for different groupings of the same set of points used to generate the voronoi (which are visible in the block).

[mbostock]

You have coincident points in your input. Remove those coincident points before computing the Voronoi (e.g., by using d3.nest).

http://bl.ocks.org/mbostock/2b070f9c7fa8f44eb2f0/288458fc4b7ff4b13d52ac5a279518f1a249fde9