{
  "release_id": "light-images-p3-20261006",
  "kind": "licensed-cartographic-image-comparison",
  "nightImage": {
    "year": 2016,
    "source": "NASA Black Marble",
    "unit": "display RGB, not radiance",
    "url": "https://science.nasa.gov/earth/earth-observatory/earth-at-night/maps/"
  },
  "skyImage": {
    "year": 2020,
    "author": "David Lorenz",
    "source": "https://commons.wikimedia.org/wiki/File:World_light_pollution.jpg",
    "file": "https://upload.wikimedia.org/wikipedia/commons/archive/6/69/20231003020239%21World_light_pollution.jpg",
    "revision": "2021-10-31 original",
    "license": "Attribution-only; redistribution, derivatives and commercial use permitted",
    "permissionTicket": "2021120610011763",
    "sha256": "eb4b7c42d863da0de1a6a221ddbfd87c245b3f3a2c6282a5bc28b309d824d17e",
    "publishedDomainSource": "https://djlorenz.github.io/astronomy/lp/",
    "domain": [
      -180,
      -65,
      180,
      75
    ],
    "processing": "Colours retained; embedded key omitted; affine coastline registration corrects east–west displacement of the source image.",
    "unit": "published model colour classes; no numeric readout",
    "registration": {
      "revision": "coast-registration-r07",
      "method": "Affine registration of the licensed cartographic image against independent geographic coastlines; no brightness values inferred",
      "destinationPixelsFromInitialMap": {
        "xScale": 1.002752877691185,
        "xOffset": 103.9065465713237,
        "yScale": 0.9984327039193669,
        "yOffset": 2.454448768388013
      },
      "outputGrid": "3600 × 1800, north-to-south, 0.1 degrees",
      "coastDistanceClippedMeanPixels": {
        "before": 7.537636499984158,
        "after": 2.3541936024897527
      },
      "regionalMedianResidualPixels": {
        "Americas": 1.22,
        "AfricaEurope": 3.35,
        "AsiaAustralia": 0.69
      },
      "limitation": "Approximate registration of a published image; not a georeferenced numeric atlas or a point measurement."
    }
  },
  "limitations": [
    "2016 satellite display image and 2020 model map are different quantities and years; not a time trend",
    "No numeric sky brightness, star counts or Bortle readout reconstructed from image pixels",
    "No coverage outside 65 S to 75 N or in omitted embedded-key footprint",
    "Map-image licence does not clear the author’s underlying numeric model files"
  ],
  "verified": "2026-10-06"
}