{
  "id": "silent-city",
  "name": "Silent City",
  "group": "Inside the amphitheater",
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  "priority": 1,
  "source_ids": [
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    "nps-sunset",
    "usgs-geonames"
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  "question": "When do separate spires read as a continuous wall?",
  "interaction": "section",
  "theme": "Rows become a city",
  "view_yaw": 1.25,
  "view_pitch": 0.68,
  "schema": 1,
  "kind": "landscape-study",
  "checked_at": "2026-10-02",
  "surface_method": "upper-envelope",
  "geometry_status": "Derived from measured airborne returns; upper-envelope terrain study, not a closed rock scan",
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    "native_horizontal": "NAD83(2011) / UTM 12N (EPSG:6341)",
    "ept_horizontal": "WGS84 Pseudo-Mercator (EPSG:3857)",
    "export_horizontal": "WGS84 / UTM 12N (EPSG:32612)",
    "vertical": "NAVD88, Geoid12B; source heights retained",
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    "vertical_exaggeration": 1,
    "transform_note": "EPT projection transformed with pyproj; no claim of survey-grade datum alignment. Centimetre export quantization is not source accuracy."
  },
  "statistics": {
    "returns_in_crop": 10321066,
    "density_returns_per_m2": 39.372,
    "ground_returns": 1763945,
    "retained_returns": 6722473,
    "vegetation_candidate_returns": 3598593,
    "excluded_noise_or_other": 2857,
    "directly_observed_node_fraction": 0.9966827399883725,
    "interpolated_node_fraction": 0.003317260011627509,
    "unsupported_node_fraction": 0.0,
    "isolated_high_cells_repaired": 35,
    "maximum_nearest_fill_m": 3.0,
    "cell_m": 1.0,
    "source_heights_m": [
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    "surface_heights_m": [
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    "intensity_display_percentiles": [
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    ],
    "vertical_surfaces": "An upper envelope can join returns across a steep face; it cannot recover undercuts, windows, or unseen interiors.",
    "surface_method": "upper-envelope"
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      "vertices": 16641,
      "triangles": 32768,
      "grid_nodes": 129,
      "spacing_m": 4.0,
      "degenerate_triangles": 0,
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      "grid_nodes": 513,
      "spacing_m": 1.0,
      "degenerate_triangles": 0,
      "downward_triangles": 0
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  "returns": {
    "file": "returns.glb.gz",
    "bytes": 1240688,
    "uncompressed_bytes": 2881236,
    "sha256": "ca867ca7b52226d7aee5ad175c5afc991a7f41e6239f87d13989ee4776278eda",
    "count": 120000,
    "sampling": "fixed seed 20261002, uniform without replacement from valid crop returns"
  },
  "profiles": "profiles.json.gz",
  "camera": {
    "yaw": 1.25,
    "pitch": 0.68,
    "distance_m": 1024,
    "target": [
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  "bounds_local": [
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      -256.0
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    [
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  "source_dataset": {
    "id": "USGS_LPC_UT_Southern_QL1_2018_LAS_2019",
    "acquired": "2018-04-27 / 2018-07-29 project interval",
    "published": "2019-06-03",
    "url": "https://registry.opendata.aws/usgs-lidar/",
    "license": "US Government Public Domain",
    "credit": "Map services and data available from U.S. Geological Survey, National Geospatial Program."
  },
  "processing": {
    "mesh": "Vegetation heuristic applied to an upper envelope. Highest retained return per nearest grid node; nearest interpolation up to 3 m; isolated spikes exceeding all 8 neighbors by 6 m lowered to neighbor maximum. No morphological closing.",
    "vegetation": "Source classes 3/4/5 plus low-intensity multiple echoes and low-intensity raised returns over nearby gentle classified ground are excluded. This is an imperfect heuristic, not a species/rock classifier.",
    "lighting": "Normals and static 12-direction terrain occlusion are derived; material color, studio lighting and display category colors are illustrative.",
    "detail": "Three nested node grids; no-data cells omitted at every LOD; low LOD can omit extra edge triangles to preserve holes."
  },
  "limitations": [
    "Hidden rock surfaces, undercuts and windows are not reconstructed.",
    "A vertical face is an interpolated connection between top-surface samples, not a wall scan.",
    "Vegetation filtering can leave crowns or remove dark rock; inspect the return view.",
    "NAIP is overhead imagery from a different year; it cannot supply photographic detail on vertical faces.",
    "The cut boundary is an editorial crop; there is no modeled geology beneath it.",
    "No route, current condition, erosion rate or collapse forecast is inferred."
  ],
  "posters": {
    "large": "poster.webp",
    "small": "poster-small.webp"
  },
  "quality_status": "accepted_educational_landscape",
  "quality_record": "quality.json",
  "textures": [
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      "file": "aerial.webp",
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      "height": 854,
      "bytes": 250174,
      "sha256": "13dbf1e93fb0b5da24fac1a4b7e219bf24d282d3838bf376ab323915719ba09f",
      "source": "imagery.json",
      "license": "US Government Public Domain, USDA NAIP"
    },
    {
      "file": "aerial-small.webp",
      "width": 512,
      "height": 512,
      "bytes": 92680,
      "sha256": "2ce5ded59216027b8fe89dce0a6d225c1b5dc0f0247895eab9fdd9ae2e034399",
      "source": "imagery.json",
      "license": "US Government Public Domain, USDA NAIP"
    }
  ]
}