basonjui / hexagon-grid-system Goto Github PK

Hello,
thanks for your work.
I have this sample which result a non-symmetric hexagon

{
    "latitude": 52.513337,
    "longitude": 13.326161,
    "radius": 10000
}

Purpose

Reduce the overall required hexagons to produce a complete Grid Map, without sacrificing accuracy in coverage.

Criteria

1. Grid map has less hexagons compare to previous algorithm
2. Grid map must ensure coverage for given boundary, regardless of where Centroid is placed.

Benchmark

Previous algorithm output

------------Tessellation stats------------
Boundary: GisBoundary(minLat=21.0, minLng=105.0, maxLat=23.383333, maxLng=109.466667)
Great-circle distance: 531312.330953638
Minimum required rings: 616
Total hexagons: 1136521

Descriptions

This issue cause hexagons to be flipped vertically when projected on maps (tested on www.geojson.io).

Sample data:

• https://gist.github.com/wavded/1200773?short_path=99c1af9

No major issue yet due to GeoJSON support backward compatibility.
But this cause our Hexagon's direction system to not work correctly. It will effect the following features:

• To be fully control in generating hexagons in expected directions (visual).
• Grouping of hexagons in expected directions (visual).

GeoJSON constraint

• https://datatracker.ietf.org/doc/html/rfc7946#section-3.1.6

Right-hand rule

• https://en.wikipedia.org/wiki/Right-hand_rule#Coordinates

Tessellation configurations

final Coordinates origin = new Coordinates(106, 15);

final Hexagon hexagon_750 = new Hexagon(origin, 750);

final Boundary oct_17_boundary = new Boundary(
                new Coordinates(102.050278, 23.583612),
                new Coordinates(109.666945, 8)
);

Missing wards data

Visualization of the problem

Top corner coordinates

latitude: 24.3628, longitude: 106.000

Left corner coordinates

latitude: 19.6814, longitude: 97.8916