{
  "status": "Exploratory numerical resolution audit; no AI model or archaeological detector run",
  "source": {
    "title": "Geersen 2024 AUV multibeam survey",
    "url": "https://doi.iow.de/10.12754/DATA-2024-0001",
    "download": "https://doi.iow.de/doi/2024/data-2024-0001/data-2024-0001.zip",
    "license": "CC BY 4.0",
    "credit": "J. Geersen; AUV data acquired by DLR during Littorina cruise L0123 (2023)",
    "path": "data/submerged/baltic/data-2024-0001.zip",
    "sha256": "a4bb3cede3fb922bfd033507b6a0a8681a9830efe541d73d18be9eed70c09ea5",
    "grid_sha256": "1dc4f7e91a31ab164c5ce6ae1bd140d1d7117811afd7fedb93a3ec0eb4a25172"
  },
  "grid": {
    "width": 2355,
    "height": 742,
    "spacing_m": 0.5,
    "crs": "EPSG:32632 \u00b7 WGS 84 / UTM zone 32N",
    "upper_left_m": [
      660882.4098479152,
      6005336.889486528
    ],
    "valid_cells": 663281,
    "total_cells": 1747410,
    "depth_min_m": -21.940000534057617,
    "depth_max_m": -20.209999084472656,
    "vertical_datum": "Not resolved from the GeoTIFF metadata; within-survey relative relief only"
  },
  "method": {
    "block_origin": "upper left of the original grid",
    "aggregation": "arithmetic mean of valid source cells; partial blocks retained; no interpolation into missing areas",
    "local_relief": "original depth minus normalised Gaussian mean, sigma 10 metres; retain centres with at least 95% observed Gaussian support; block-average this fixed residual field",
    "local_support_cells": 502232,
    "local_variance_m2": 0.0006220831755827508,
    "missing": "Masked, never interpreted as absence of archaeology",
    "comparison": "RMSE at the same original observed cells. Local variance at the same supported cells; descriptive, not a detection rate."
  },
  "results": [
    {
      "spacing_m": 0.5,
      "valid_blocks": 663281,
      "depth_rmse_m": 0.0,
      "depth_max_abs_error_m": 0.0,
      "local_variance_retained": 1.0
    },
    {
      "spacing_m": 2.0,
      "valid_blocks": 42081,
      "depth_rmse_m": 0.01796945254200685,
      "depth_max_abs_error_m": 0.7253381013870239,
      "local_variance_retained": 0.49109398231534096
    },
    {
      "spacing_m": 5.0,
      "valid_blocks": 6900,
      "depth_rmse_m": 0.021390519112916062,
      "depth_max_abs_error_m": 0.9352803802490222,
      "local_variance_retained": 0.3316685495050253
    },
    {
      "spacing_m": 10.0,
      "valid_blocks": 1802,
      "depth_rmse_m": 0.026396281459915946,
      "depth_max_abs_error_m": 1.0713956260681137,
      "local_variance_retained": 0.17746052303041124
    },
    {
      "spacing_m": 25.0,
      "valid_blocks": 322,
      "depth_rmse_m": 0.04153026904808674,
      "depth_max_abs_error_m": 1.0569691543579118,
      "local_variance_retained": 0.045663081063170394
    },
    {
      "spacing_m": 115.0,
      "valid_blocks": 24,
      "depth_rmse_m": 0.1264137188748301,
      "depth_max_abs_error_m": 0.8408852864037257,
      "local_variance_retained": 0.0032291071711556
    }
  ],
  "limitations": [
    "One known-site survey, selected after publication; no blind or independent archaeological labels.",
    "115 m square blocks illustrate loss of detail; they do not reproduce EMODnet\u2019s angular grid, original measurements, interpolation or datum.",
    "No recovery model, AI classification, wall trace or new archaeological feature is claimed.",
    "Different grid origins, survey noise, object size and relief affect these measurements."
  ],
  "figure": {
    "path": "img/submerged/baltic-resolution.png",
    "sha256": "4a781a493a90c5d46722840fc0503480d2a1875a1122150a5694725d3d455a90"
  }
}