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A5 - a pentagonal geospatial index: https://a5geo.org If you’ve used H3 the semantics should be familiar. The biggest differentiator is the fact that cells have exactly the same ar…

70 years ago today, on December 9th 1955, the Council of Europe adopted the flag we all recognize . Hidden in plain sight for seven decades is a perfect geometric secret. Central t…

Nice library. Without trying to start the classic geo-flamewar, do you consider returning the DD coordinates as [longitude, latitude]? This is in line with a number of formats out …

It is a common misconception that h3 is equal area. At any resolution level the cell size varies by a factor of 2, which is (roughly) the same as S2. See the following visualizatio…

Very impressive results, cool to see innovation in this space! I’d definitely be interested in a follow up post going into the details of the geometric algorithms. I’m working on m…

This agrees with my experience on a project I’ve been working on this year, in particular related to porting the code. I’ve developed a strategy that I’m calling “Polyglot Mirrorin…

I've been working on a geospatial library, https://a5geo.org this year. Originally I wrote the code in TypeScript but have since ported to Python and Rust with the aid of Claude Co…

https://news.ycombinator.com/item?id=43971314 got some attention here, when I originally released the TypeScript version, so following up with the news that the library has now bee…

My mistake, you are correct. The base solid is indeed the rhombic dodecahedron. I believe the point about the angular defect is still valid though.

Yes, such indices (S2 & H3) are widely used for providing a index in databases, so geospatial features that are close by in the world and stored in nearby databases rows. https://c…

A5 cell boundaries are geodesics. One more difference that I thought of is that HEALPix is generally not aligned with the continents (makes sense as it is mostly used for astrophys…

If you're aggregating and comparing data across different locations for example: https://a5geo.org/examples/airbnb

The base platonic solid that Healpix is based on is the octahedron ( https://en.wikipedia.org/wiki/Octahedron ), which A5 uses the dodecahedron( https://en.wikipedia.org/wiki/Regul…

Bear in mind that this is a "Show HN", the library was released just a few weeks ago! Whereas the other libraries have been around for a decade+ The plan is certainly to release ve…

For a visual explanation of how the system works, as well as interactive examples, check out the project website at https://a5geo.org/examples/

As a user, you generally don’t care about the math (and S2 is hardly simple either, as it warps the squares prior to projection). You just call the API and use the indices for spat…

Also check S2: http://s2geometry.io/ , created at Google before H3, which uses squares and underpins the fast indexing in BigQuery amongst many other things

Yes, those are the obvious ones. This example: https://a5geo.org/examples/airbnb shows why the equal area is valuable in practice, while https://a5geo.org/examples/area shows the a…

The cells being the same shape is useful in some use cases and irrelevant in others. For example, see the Airbnb demo: https://a5geo.org/examples/airbnb . The H3 tiles are very dif…

No, it is based on applying a lattice onto the faces of a dodecahedron (technically a pentakis dodecahedron). Take a look at https://a5geo.org/examples/teohedron-dodecahedron and o…

A pentagonal geospatial indexing system: https://a5geo.org/ If you’ve used H3 or S2 it should be familiar, the major difference (apart from the fact it uses pentagons) is that the …