{
  "title": "Eureka, Colorado \u2014 USGS 3DEP landscape exploration",
  "acquisition": {
    "project": "CO_SanJuan_NF_2017",
    "start": "2017-09-16",
    "end": "2017-10-24",
    "platform": "Airborne lidar; no drone provenance claimed",
    "provider": "Woolpert / USGS 3DEP",
    "tileFlightDate": "Not verified"
  },
  "license": "US Government public-domain 3DEP data; USGS and Microsoft Planetary Computer attribution retained",
  "source": {
    "stac": "https://planetarycomputer.microsoft.com/api/stac/v1/collections/3dep-lidar-copc/items/USGS_LPC_CO_SanJuan_NF_2017_13SBB740950_LAS_2018",
    "metadata": "https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/CO_San_Juan_2017_D17/CO_SanJuan_NF_2017/xml/CO_San_Juan_2017_D17_Classified_Point_Cloud.xml",
    "asset": "https://usgslidareuwest.blob.core.windows.net/usgs-3dep-copc/usgs-copc/USGS_LPC_CO_SanJuan_NF_2017_LAS_2018/copc/USGS_LPC_CO_SanJuan_NF_2017_13SBB740950_LAS_2018.copc.laz",
    "bytes": 83335712,
    "sha256": "b4bf1decf453868d253ae3552925aa6db04b6bc13df75b69d639dac57d39c95f",
    "tileCount": 22169831,
    "cropCount": 4677185,
    "retainedAfterNoiseExclusion": 4676354
  },
  "referenceSystem": {
    "header": "EPSG:26913 plus EPSG:5703 (NAVD88)",
    "projectNarrative": "NAD83(2011), UTM13N; GEOID12B",
    "note": "Source declarations differ. Coordinates retained as supplied, with no claimed realized-datum transformation. Not an operational measurement tool."
  },
  "preparation": {
    "cropBounds": [
      274016,
      4195516,
      274400,
      4195900
    ],
    "origin": [
      274208,
      4195708,
      3000
    ],
    "exclusions": "Classes7/18, withheld returns, elevations outside2900\u20133500m",
    "subsampling": "Stable coordinate/class hash, 900000 source returns; 300000-point nested narrow set. Original coordinates quantized to nearest5cm. No new returns generated.",
    "ground": "One-metre grid, mean classified-ground elevation per cell; inverse-distance interpolation only from observed grid cells within2m; larger gaps excluded from triangles. No smoothing or vertical exaggeration.",
    "pointToGround": "Core2017ground and returns unchanged. Surrounding2024DEM provides regional context; see regionalContext for visual seam treatment.",
    "scene": {
      "origin": [
        274208,
        4195708,
        3000
      ],
      "bounds": [
        274016,
        4195516,
        274400,
        4195900
      ],
      "coordinates": [
        -107.567381,
        37.880899
      ],
      "ground": {
        "file": "assets/ground.f32",
        "mask": "assets/ground-mask.u8",
        "size": 385,
        "spacing": 1,
        "source": "Derived from the same 2017 classified ground returns",
        "measuredCells": 144022,
        "interpolatedCells": 4171,
        "excludedCells": 32
      },
      "points": {
        "levels": [
          {
            "file": "assets/returns-base.bin",
            "count": 300000,
            "bytes": 2100000,
            "gzipBytes": 1019646,
            "sha256": "47d5386f104aeffaed0698310d7e9ddecb40180c4963c7476988428d2bd814de"
          },
          {
            "file": "assets/returns-detail.bin",
            "count": 600000,
            "bytes": 4200000,
            "gzipBytes": 2012648,
            "sha256": "87ee3eda8a3979218db9922846b3d97e4e6fca13c6da3f683b944faf8edf947e"
          }
        ],
        "encoding": "Three uint16 delta planes (x,y,z), then uint8 classification plane. Reconstruct each axis with modulo65536 cumulative sum; coordinates at0.05m.",
        "quantizationMetres": 0.05,
        "positionBase": [
          -192,
          -100,
          -192
        ],
        "sourceLabel": "2017 aerial lidar \u00b7 CO_SanJuan_NF_2017. Ground surface derived from this same scan.",
        "classes": {
          "1": 2766992,
          "2": 1906418,
          "17": 2944
        }
      }
    },
    "context": {
      "bounds": [
        274000,
        4195000,
        275000,
        4196000
      ],
      "localBounds": [
        -208,
        -292,
        792,
        708
      ],
      "ground": {
        "file": "assets/context-ground.f32",
        "mask": "assets/context-mask.u8",
        "size": 251,
        "spacing": 4,
        "start": [
          -208,
          -292
        ],
        "measuredCells": 62926,
        "interpolatedCells": 74,
        "excludedCells": 1
      },
      "points": {
        "levels": [
          {
            "file": "assets/context-base.bin",
            "count": 50000,
            "bytes": 350000,
            "gzipBytes": 209466,
            "sha256": "e1fc7110d80509d00547a9d0eadba8d00c541d8198889d4bee9a9af1b6aad4ec"
          },
          {
            "file": "assets/context-detail.bin",
            "count": 50000,
            "bytes": 350000,
            "gzipBytes": 209400,
            "sha256": "021216149b6d9744204631aadf72e6cabb76bb73122b58238d37d4fe4a9d49a7"
          }
        ],
        "positionBase": [
          -208,
          -100,
          -292
        ],
        "quantizationMetres": 0.05
      }
    },
    "contextMethod": "Same source tile, 4m mean classified-ground grid. Only observed adjacent cells within4m fill holes. Excludes the detailed core mesh at render time; shared boundary follows the1m core.100000 additional original returns selected by coordinate/class hash;50000 on narrow layouts. No source points synthesized. Loaded after the coherent core frame."
  },
  "limitations": [
    "Airborne scan is incomplete beneath occlusion; classified ground is a processed interpretation.",
    "Class1 is unclassified, not a vegetation or building label. Ground mode hides all non-ground returns.",
    "Finite capture area, deliberately bounded navigation; no operational volume, hazard or clearance outputs."
  ],
  "presentation": {
    "palette": "Fixed mineral shading; illustrative colors",
    "navigation": "Surface-grab pan, continuous yaw, cursor-directed zoom; camera clearance and distant regional bounds.",
    "historicalPhoto": "Separate unregistered 1940 reference; see history-source.json"
  },
  "regionalContext": {
    "project": "USGS3DEP UT_COUTAML_D24",
    "acquisition": "2024; separate from2017lidar",
    "source": "https://prd-tnm.s3.amazonaws.com/StagedProducts/Elevation/1m/Projects/UT_COUTAML_D24/TIFF/USGS_1M_13_x27y420_UT_COUTAML_D24.tif",
    "sourceSha256": "ea9e4b37b4e7c199e70af3ac58dd4f5cb7cfc10dc2e82b65f6f5eb7b37fac9a6",
    "crs": "EPSG:26913 / NAVD88 metres",
    "method": "4m intermediate ring and20m far bilinear samples from cached1mDEM; noNoData filling. Natural verticalscale. Localz=originNorthing-northing.",
    "grid": {
      "file": "assets/region.f32",
      "mask": "assets/region-mask.u8",
      "size": 201,
      "spacing": 20,
      "start": [
        -1708,
        -1792
      ],
      "localBounds": [
        -1708,
        -1792,
        2292,
        2208
      ],
      "minimum": 2972.376708984375,
      "maximum": 4085.69580078125,
      "validSamples": 40401,
      "sha256": "e234ed08e254ef87cca08c1f4ea48ef52cfff88a7b8606ce9249f9494f319604",
      "gzipBytes": 132555
    },
    "nearGrid": {
      "file": "assets/near.f32",
      "mask": "assets/near-mask.u8",
      "size": 401,
      "spacing": 4,
      "start": [
        -508,
        -592
      ],
      "localBounds": [
        -508,
        -592,
        1092,
        1008
      ],
      "minimum": 2990.562744140625,
      "maximum": 3695.7197265625,
      "validSamples": 160801,
      "sha256": "cf73fb2769a741c96fae67fd26cecd63f6751ba79c2ff42c7e9f6d417243b5e0",
      "gzipBytes": 508331
    },
    "seam": "The4m intermediate DEM ring matches every2017context edge vertex; elevations transition to2024DEM over80m outside scan. A triangulated transition joins that ring to the20mfar grid. Existing lidar geometry and all original point coordinates unchanged. Not a registered multi-epoch measurement product."
  },
  "delivery": {
    "scene": "data/scene.json",
    "encoding": "Explicit gzip data files decoded by native DecompressionStream.",
    "note": "File names within preparation and regionalContext below record the original preparation outputs. The current scene manifest supplies deployed paths relative to the exploration module directory.",
    "fallback": "fallback.webp; static rendering of this same landscape, used only when interactive graphics cannot load."
  }
}