{
  "description": "Qualitative thresholded raster tracing; not CAD and not a numerical contour dataset. No physical interpolation.",
  "source": "NASA-TP-2000-210387 physical page31 printed25 Figure4",
  "crop_full_render": [
    450,
    340,
    1440,
    1340
  ],
  "render_sha256": "9d98be693868e4d4d2e7359f106c11241497f08e05c64b0ebe60e3d6d39fcc52",
  "calibration": {
    "origin_crop": [
      20.0,
      946.0
    ],
    "mach25_vector": [
      930.0,
      16.0
    ],
    "altitude250kft_vector": [
      20.0,
      -925.0
    ],
    "mapping": "plot normalized coordinates = inverse(basis) * (crop pixel - origin)",
    "type": "approximate affine deskew; axis endpoint selection visual"
  },
  "threshold": 120,
  "minimum_component_pixels": 10,
  "exclusions_crop_pixels": [
    [
      125,
      120,
      340,
      325
    ],
    [
      745,
      682,
      775,
      722
    ],
    [
      777,
      510,
      820,
      550
    ]
  ],
  "limit": "Labels 1 and10 are preserved at source positions but cannot be reliably assigned to particular strokes. Filled region values/meaning remain unspecified."
}