Average Hexagon Length value incorrect in restable

[jrl53]

It seems that the column Average Hexagon Edge Length (km) in the restable is undershooting the actual length of the hexagon edges.

The Average Hexagon Area (km2) column seems correct when calculating in QGIS (with correct projection), and also measuring the edge in QGIS gives a different number.

Moreover, the edge length does not correspond if we calculate a hexagon based on it's formula.

For example, at res7 the edge length should be ~1.5 km, not 1.22 km.

[nrabinowitz]

Are you using QGIS to calculate average hexagon edge length across the grid, or just in some local area? There is area and edge-length variation across the grid - see https://observablehq.com/@nrabinowitz/h3-area-variation for a visualization of this, and see https://observablehq.com/@nrabinowitz/h3-area-stats for a table of the area and edge length stats.

You can also use exactEdgeLength to calculate the average edge length for a single cell, which should be more accurate (though it uses a spherical model of the Earth, so may not correspond exactly if you're calculating over a geoid model).