{
  "sourceProjection": "Mercator (museum catalog); painterly historic map",
  "outputProjection": "equirectangular WGS84 geographic; full world bounds -180,90,180,-90; pixel centers",
  "originalScanPixels": [
    21448,
    12515
  ],
  "sourceUsedPixels": [
    5362,
    3129
  ],
  "outputPixels": [
    4096,
    2048
  ],
  "fit": "Robust affine alignment in spherical Mercator to Natural Earth 110m coastlines, using coastline detected from map color, excluding poles and antimeridian",
  "pixelTransformAt1600Width": {
    "x": [
      254.76246822276897,
      0.09039709545640646,
      799.7426304465429
    ],
    "y": [
      -0.44401260724053043,
      -253.04500261400128,
      467.79143710074777
    ],
    "formula": "x=a*longitude_radians+b*log(tan(pi/4+latitude_radians/2))+c; same for y"
  },
  "errorAt1600WidthPx": {
    "median": 1.0712847007117072,
    "mean": 2.042637714443447,
    "p90": 3.6053838690529165
  },
  "limitation": "Approximate georeferencing of painterly map, not survey-grade; polar caps absent in the source are transparent; longitude edges may have a narrow unmapped seam because the scan is cropped; keep NOAA terrain depth label separate from historical art. No elevations were inferred from image colors."
}