substack

@substack

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  1. Pinned Tweet
    24 Sep 2020

    4 replies 7 retweets 76 likes
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  2. Apr 13

    giving a pre-recorded talk about eyros, a p2p spatial database, on april 29 for

    4 retweets 26 likes
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  3. Jan 18

    still some issues if i perturb the coordinates but i'm going to focus on building natural earth data into eyros/georender until i encounter clipping bugs

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  4. Jan 18

    finally got everything working solid for clipping, working on this for 6 weeks. much of that was handling the edge case where a point lies exactly on a line segment and shared vertices

    cylindrical projection world map divided into 4 quadrants where the land area is excluded by the quadrant polygons
    1 reply 4 retweets 19 likes
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  5. 26 Dec 2021

    added martinez and polygon-clipping to quickly compare output and the ability to load data from urls

    2 replies 4 likes
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  6. 26 Dec 2021

    now i can debug these more easily

    two complex polygons with holes, their intersection is visible in purple with textareas to input each polygon
    1 reply 13 likes
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  7. 24 Dec 2021

    noticed another spot to make a small perf improvement while working on the rust version, walking the nextPolygon links instead of recalculating some things

    martinez $ npm run bench > martinez-polygon-clipping@0.7.1 bench /home/substack/projects/martinez > node --require reify bench.js Hole_Hole Martinez x 34,282 ops/sec ±0.68% (92 runs sampled) JSTS x 2,696 ops/sec ±12.59% (86 runs sampled) pclip x 123,111 ops/sec ±0.70% (92 runs sampled) - Fastest is pclip Asia union Martinez x 8.44 ops/sec ±5.72% (25 runs sampled) JSTS x 8.35 ops/sec ±1.60% (25 runs sampled) pclip x 12.93 ops/sec ±3.78% (37 runs sampled) - Fastest is pclip States clip Martinez x 203 ops/sec ±1.54% (78 runs sampled) JSTS x 100 ops/sec ±3.54% (73 runs sampled) pclip x 641 ops/sec ±0.92% (87 runs sampled) - Fastest is pclip
    1 reply 3 likes
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  8. 24 Dec 2021

    there's less of a speedup with the middle benchmark because that is the biggest file (1.2M) and pclip naively compares every edge to every other edge for n² comparisons, but that is straightforward to improve with an interval tree or similar

    1 reply 2 likes
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  9. 24 Dec 2021

    also making a rust version which should blow this out of the water even more. but it will be interesting to see how a wasm build compares against js

    1 reply 4 likes
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  10. 24 Dec 2021

    i was only trying to make something pluggable so i could operate in lon/lat space with great circles directly because of all the problems i had with other libraries around the antimeridian and high latitudes

    1 reply 1 like
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  11. 24 Dec 2021

    lol my new polygon clipping tool is pretty fast this is using the benchmark from JSTS is turf/union which uses the polygon-clipping pkg

    martinez $ npm run bench > martinez-polygon-clipping@0.7.1 bench /home/substack/projects/martinez > node --require reify bench.js Hole_Hole Martinez x 32,669 ops/sec ±0.77% (91 runs sampled) JSTS x 2,563 ops/sec ±12.13% (83 runs sampled) pclip x 117,349 ops/sec ±0.93% (90 runs sampled) - Fastest is pclip Asia union Martinez x 7.41 ops/sec ±11.01% (22 runs sampled) JSTS x 7.03 ops/sec ±3.29% (22 runs sampled) pclip x 10.21 ops/sec ±4.21% (30 runs sampled) - Fastest is pclip States clip Martinez x 182 ops/sec ±1.41% (82 runs sampled) JSTS x 96.46 ops/sec ±1.60% (70 runs sampled) pclip x 617 ops/sec ±0.98% (86 runs sampled) - Fastest is pclip
    1 reply 19 likes
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  12. Retweeted
    29 Nov 2021

    Recently, an acquaintance in tech asked me what, in my experience as a public librarian, makes websites and apps unusable to people with limited technology access, and after a few days thinking about it, I’m gotta put one of the biggest ones as two-factor authentication.

    75 replies 1,455 retweets 5,469 likes
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  13. 30 Nov 2021

    clipping will be good enough once i get this seam at the antimeridian to disappear

    world map with a cylindrical projection showing a region from far western siberia to eastern greenland with a northernmost polar ocean boundary around the antimeridian with some triangular chunks taken out of it
    2 likes
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  14. 26 Nov 2021

    map of alaska and western canada with cities, rivers, and large chunks of missing geometry from clipping errors as well as a giant blue triangle over western alaska
    1 reply 5 likes
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  15. 24 Nov 2021

    i don't think this map is accurate

    glitchy map of alaska and some of northwestern cananda but every town is labeled "anchorage"
    5 replies 4 retweets 54 likes
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  16. 19 Nov 2021

    urban areas

    map of europe with rivers and urban areas
    1 retweet 10 likes
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  17. 18 Nov 2021

    skipped clipping and i'll include the full features with each of their extents queried directly from the database

    map of middle-latitude eastern north america showing the mississippi and missouri watersheds, great lakes, and other rivers
    1 reply 8 likes
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  18. 17 Nov 2021

    now to figure out why these rivers cut back on themselves

    map of south america with rivers that have straight lines connecting the start and end of each segment, seemingly
    2 replies 3 likes
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  19. 16 Nov 2021

    not the most even refinement but i think this will be ok

    map of antarctica with wireframe and somewhat even triangles but they get narrow in places
    1 reply 4 likes
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  20. 16 Nov 2021

    fixed if i do the subdivision in [lon,lat] space but that uses degrees for the distance, so i need to convert that to meters on a sphere while doing lerp in [lon,lat]

    map of antarctica with a red wireframe overlay that converges into a dense spiral around the south pole
    2 replies 8 likes
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  21. 16 Nov 2021

    with steiner points it's still not working, because the triangularization happens in [lon,lat] space. i think carving this up against a grid will work though

    1 reply 2 likes
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