d3.geoBounds gives incorrect bounds for one of the polygons in world-atlas countries50, Fiji)

[jrus]

If I do:

const countries50 = (() => {
  const
    url = "https://cdn.jsdelivr.net/npm/world-atlas@2/countries-50m.json",
    raw = await fetch(url),
    topo = await raw.json();
  return topojson.feature(topo, topo.objects.countries);
})();

const fiji = countries50.features[170];
const polygon = ({ type: 'Polygon', coordinates: fiji.geometry.coordinates[15] })
const bounds = d3.geoBounds(polygon)

The result is [[-180,-16.541749856561054],[180,-16.43238163897263]]

I would instead expect the left longitude to be 179.something and the right longitude to be -179.something.

After conversion from topojson to geojson, the polygon in question has coordinates:

[
  [180,-16.54001385310727],
  [179.9855998559986,-16.541749856561054],
  [179.9855998559986,-16.522653818569424],
  [-180,-16.48966975294752],
  [-179.94239942399423,-16.441061656241544],
  [-179.89919899198992,-16.43238163897263],
  [-179.9279992799928,-16.479253732224805],
  [-179.9279992799928,-16.503557780577793],
  [-180,-16.54001385310727],
  [180,-16.54001385310727]
]

[jrus]

While we are at it, I haven’t investigated closely, but countries50’s Antarctica gets a bounding box that does not go all the way to the south pole.

Graphically, both of these issues result in:

Edit:

uh....

Ring 0 of the polygon:

{
  var antarctica = JSON.parse(JSON.stringify(countries50.features[239].geometry));
  antarctica.coordinates = antarctica.coordinates.slice(2, 3);      // Polygon 2 of the MultiPolygon
  antarctica.coordinates[0] = antarctica.coordinates[0].slice(0,1); // Ring 0 of the Polygon
  return d3.geoBounds(antarctica);
}

-> [[-180,-90], [180,90]]

Ring 1 of the polygon:

{
  var antarctica = JSON.parse(JSON.stringify(countries50.features[239].geometry));
  antarctica.coordinates = antarctica.coordinates.slice(2, 3);      // Polygon 2 of the MultiPolygon
  antarctica.coordinates[0] = antarctica.coordinates[0].slice(1,2); // Ring 1 of the Polygon
  return d3.geoBounds(antarctica);
}

-> [[-180,-90], [180,-63.22635473573485]]

Rings 0 and 1 together:

{
  var antarctica = JSON.parse(JSON.stringify(countries50.features[239].geometry));
  antarctica.coordinates = antarctica.coordinates.slice(2, 3);      // Polygon 2 of the MultiPolygon
  antarctica.coordinates[0] = antarctica.coordinates[0];            // Both rings of the Polygon
  return d3.geoBounds(antarctica);
}

-> [[-180,-89.99900007577445], [180,-63.22635473573485]]