{
  "id": "black-birch-canyon",
  "name": "Black Birch Canyon rim",
  "group": "The southern amphitheaters",
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  "surface_method": "classified-ground",
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    "nps-pois",
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  "place_ids": [
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  "theme": "Following the dissected edge",
  "question": "How do the smaller hollows divide the rim?",
  "interaction": "section",
  "view_yaw": 1.0,
  "view_pitch": 1.12,
  "schema": 1,
  "kind": "landscape-study",
  "checked_at": "2026-10-02",
  "geometry_status": "Derived from source-classified ground returns; terrain study, not a closed rock scan",
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    "ept_horizontal": "WGS84 Pseudo-Mercator (EPSG:3857)",
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    "units": "metres",
    "axes": "x east, y up from base_m, z south",
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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."
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    "density_returns_per_m2": 34.194,
    "ground_returns": 4535384,
    "retained_returns": 4535384,
    "vegetation_candidate_returns": 6463257,
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    "unsupported_node_fraction": 0.04005030987692319,
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    "cliff_or_small_patch_omission_fraction": 0.018501419240108067,
    "maximum_3x3_relief_m": 12.0,
    "minimum_connected_patch_m2": 100.0,
    "maximum_nearest_fill_m": 3.0,
    "cell_m": 1.5,
    "distance_reference": "Distance between grid-node centers, not exact source-point XY.",
    "maximum_grid_bin_offset_m": 1.0606601717798212,
    "maximum_source_xy_distance_bound_m": 4.060660171779821,
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    "surface_heights_m": [
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    "intensity_display_percentiles": [
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    ],
    "vertical_surfaces": "Abrupt interpolated cliff nodes are omitted; directly sampled bins are retained. Connecting top-surface samples still does not measure a wall, undercut, window or unseen interior.",
    "surface_method": "classified-ground"
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    "file": "returns.glb.gz",
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    "count": 120000,
    "sampling": "fixed seed 20261002, uniform without replacement from valid crop returns"
  },
  "profiles": "profiles.json.gz",
  "coverage": {
    "image": "coverage.webp",
    "data": "coverage.json.gz",
    "nodes": 513,
    "orientation": "north up; west left"
  },
  "camera": {
    "yaw": 1.0,
    "pitch": 1.12,
    "distance_m": 1536.0,
    "target": [
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    "limits": {
      "minimum_distance_widths": 1.35,
      "maximum_distance_widths": 4,
      "minimum_pitch_radians": 1.0,
      "maximum_pitch_radians": 1.55
    },
    "scope": "Above-terrain observation only; no ground-level camera or visitor-viewpoint equivalence."
  },
  "bounds_local": [
    [
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      -384.0
    ],
    [
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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": "Source class 2 ground only. 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. Interpolated nodes with more than 12 m relief across a 3x3 neighborhood and connected patches smaller than 100 m² are omitted. Directly sampled ground bins otherwise remain, including steep rims. Original returns are unchanged. 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.",
    "Abrupt interpolated cliff nodes are omitted; connections between directly sampled bins are derived facets, not measured wall surfaces.",
    "Ground classification can omit standing rock or retain classification errors; 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",
    "material": "aerial",
    "geometry_year": 2018,
    "imagery_year": 2024,
    "kind": "actual model render, not a ground photograph"
  },
  "quality_status": "qualified-ground-terrain-with-visible-omissions",
  "editorial": {
    "lede": "The plateau edge is divided into smaller hollows before it opens into the larger canyon.",
    "body": "Black Birch Canyon lies north of Rainbow Point. NPS places it within the southern amphitheater landscape. This overlook-sector crop studies the nearby rim: use the north-up plan to follow higher ridges, then move the section to compare the hollows between them.",
    "lesson": "The shape changes from one slice to the next because each section crosses a different part of the dissected edge. The scale stays fixed. The name is not evidence of a particular tree species: NPS describes Black Birch as a probable historical misidentification of aspen.",
    "limit": "This is the overlook sector, not the full named drainage. Larger-scale downstream connections and the distant skyline are outside the model; no route line is inferred.",
    "caption": "A ground-surface study of the ridges and hollows near Black Birch Canyon overlook.",
    "comparison": "The correct overlook locator is retained. A differently located NPS parking record with a similar name is excluded from this study."
  },
  "sources": [
    {
      "id": "nps-black-birch",
      "title": "Black Birch Canyon",
      "url": "https://www.nps.gov/places/000/black-birch-canyon.htm",
      "publisher": "National Park Service",
      "date": "2024-10-10",
      "retrieved_at": "2026-10-02",
      "license": "Facts paraphrased and linked. Photograph rights recorded separately per image.",
      "supports": "Overlook and southern amphitheater context; probable aspen naming confusion."
    },
    {
      "id": "nps-pois",
      "title": "NPS Public Points of Interest",
      "url": "https://mapservices.nps.gov/arcgis/rest/services/NationalDatasets/NPS_Public_POIs/FeatureServer/0",
      "publisher": "National Park Service",
      "date": "dataset records have individual dates",
      "retrieved_at": "2026-10-02",
      "license": "NPS public geospatial data; no endorsement; agency source and accuracy fields preserved",
      "supports": "Mapped overlook positions; Hat Shop Hoodoos Viewpoint 9513. Accuracy is unknown, scaled or >=14 m for used records. Existing travel coordinates remain unchanged; similar names with different roles are not substituted."
    },
    {
      "id": "gnis",
      "title": "Geographic Names — Landforms",
      "url": "https://carto.nationalmap.gov/arcgis/rest/services/geonames/MapServer/5",
      "publisher": "US Geological Survey",
      "date": null,
      "retrieved_at": "2026-10-02",
      "license": "US Government Public Domain; USGS National Map terms",
      "supports": "Independent named-feature locators, including Hat Shop 1441625, Farview 1441016, Piracy 1444459 and Corral Hollow 1439972. Points do not define a feature boundary. Valley records include multiple positions, not a trail polyline."
    }
  ],
  "imagery": {
    "publisher": "USDA Farm Service Agency / FPAC",
    "dataset": "National Agriculture Imagery Program (NAIP), Utah 2024",
    "retrieved_at": "2026-10-02T09:10:49.280051+00:00",
    "source_pixels_m": 0.6,
    "export_pixels": 1280,
    "export_pixel_m": 0.6,
    "crs": "EPSG:32612",
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      "spatialReference": {
        "wkid": 32612,
        "latestWkid": 32612
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    "flight_dates": [
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    "images": [
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        "Category": 1,
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    "catalog_url": "https://apps.geo.fpac.usda.gov/geo-imagery/rest/services/naip/conus_naip/ImageServer/query?f=json&geometry=%7B%22xmin%22%3A389018.99140963866%2C%22ymin%22%3A4149283.2391991257%2C%22xmax%22%3A389786.99140963866%2C%22ymax%22%3A4150051.2391991257%2C%22spatialReference%22%3A%7B%22wkid%22%3A32612%7D%7D&geometryType=esriGeometryEnvelope&inSR=32612&spatialRel=esriSpatialRelIntersects&outFields=%2A&returnGeometry=false&where=Category%3D1+AND+year_ts%3D2024",
    "export_url": "https://apps.geo.fpac.usda.gov/geo-imagery/rest/services/naip/conus_naip/ImageServer/exportImage?f=json&bbox=389018.99140963866%2C4149283.2391991257%2C389786.99140963866%2C4150051.2391991257&bboxSR=32612&imageSR=32612&size=1280%2C1280&format=png&pixelType=U8&interpolation=RSP_BilinearInterpolation&adjustAspectRatio=false&bandIds=0%2C1%2C2&mosaicRule=%7B%22mosaicMethod%22%3A%22esriMosaicLockRaster%22%2C%22lockRasterIds%22%3A%5B195919%2C195922%5D%2C%22mosaicOperation%22%3A%22MT_FIRST%22%7D",
    "direct_image_url": "https://apps.geo.fpac.usda.gov/geo-imagery/rest/services/naip/conus_naip/ImageServer/exportImage?f=image&bbox=389018.99140963866%2C4149283.2391991257%2C389786.99140963866%2C4150051.2391991257&bboxSR=32612&imageSR=32612&size=1280%2C1280&format=png&pixelType=U8&interpolation=RSP_BilinearInterpolation&adjustAspectRatio=false&bandIds=0%2C1%2C2&mosaicRule=%7B%22mosaicMethod%22%3A%22esriMosaicLockRaster%22%2C%22lockRasterIds%22%3A%5B195919%2C195922%5D%2C%22mosaicOperation%22%3A%22MT_FIRST%22%7D",
    "original_sha256": "80e58ae52478b1e4e1176c0634d833ec7d59917d0a0f282ce26eaaea873feb6b",
    "license": "US Government Public Domain",
    "license_url": "https://catalog.data.gov/dataset/national-agriculture-imagery-program-naip-imagery",
    "processing": "Locked 2024 primary rasters, RGB bands 0/1/2, orthographic drape; bilinear export, WebP encoding. No invented detail.",
    "limitations": "Leaf-on aerial imagery draped on 2018 filtered topography; acquisition shadows, tree crowns, temporal differences and metre-scale registration error remain. Cliff faces stretch a top-down pixel; hidden walls are not photographed."
  },
  "visual_review": {
    "checked_at": "2026-10-02",
    "views": [
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    "scope": "Above-terrain ground study only. Visible gaps remain; neither closed cliffs nor cap/neck fidelity is accepted.",
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}