PRISM LiDAR Cloud - sample deliverable package
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Source: OpenDataDC 2020 airborne LiDAR, downtown Washington DC (public domain,
        District of Columbia Office of the Chief Technology Officer / OpenDataDC).
CRS   : NAD83 Maryland State Plane (EPSG:26985), horizontal in metres.
Datum : NAVD88 orthometric heights (GEOID18). CAD deliverables are reprojected to
        NAD83(2011) / Maryland State Plane US survey feet (EPSG:6488) for surveying use.

This is a REAL end-to-end PRISM run over a 600 x 600 m block of dense downtown DC -
not a mockup. Every file below opens in standard GIS / CAD / point-cloud software.

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FILES
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PRISM_DEM_50cm.tif
    Bare-earth Digital Elevation Model (ground surface), 0.5 m grid, NAVD88 metres.
    Open in QGIS / ArcGIS Pro (drag in as a raster layer; apply a hillshade for relief).

PRISM_DSM_25cm.tif
    Digital Surface Model - the top reflective surface (buildings + tree canopy + ground),
    0.25 m grid, NAVD88 metres. Open in QGIS / ArcGIS Pro.

PRISM_CHM_25cm.tif
    Canopy Height Model (CHM = DSM - DEM): height of vegetation/structures above bare ground,
    0.25 m grid, metres. Open in QGIS / ArcGIS Pro.

PRISM_DEM_uncertainty.tif
    Per-cell DEM ground-support uncertainty index (0 = well-supported bare ground,
    1 = unsupported / interpolated). 0.5 m grid. Open in QGIS / ArcGIS Pro.

PRISM_classified_pointcloud_sample.las
    ASPRS-classified airborne point cloud (LAS 1.4). Decimated sample (~40% of the full
    cloud, ~1.3M points) - classification is preserved: ground, low/medium/high vegetation,
    building, water. Open in CloudCompare or QGIS (LAS/LAZ). Color by "Classification" to
    see the semantic labels.

PRISM_AOI_boundary.geojson
    Area-of-interest boundary polygon (EPSG:26985). Open in QGIS / any GeoJSON viewer.

PRISM_topo_CAD.dxf
    Survey CAD topo: elevation contours + labeled spot elevations, in NAD83(2011) Maryland
    State Plane US survey feet, NAVD88. Open in AutoCAD / Civil 3D / BricsCAD / any DXF reader.

PRISM_surface_TIN.xml
    LandXML triangulated surface (TIN) of the terrain, for Civil 3D / survey software.
    Open in Civil 3D (Import LandXML) or any LandXML-aware package.

PRISM_CAD_metadata.txt
    Survey stamp / provenance for the CAD deliverables (datum, grid-to-ground combined
    scale factor, geoid model, engine version).

PRISM_FGDC_metadata.xml
    FGDC CSDGM (FGDC-STD-001-1998) geospatial metadata record for the elevation products -
    the metadata format USGS 3DEP / FEMA / DOT bundles expect. Open in any text/XML viewer
    or an FGDC metadata editor.

PRISM_accuracy_report.docx
    Editable accuracy report (Microsoft Word) including the USGS 3DEP surface-agreement
    cross-check, point-classification breakdown, point-density metrics, and datum/CRS
    provenance. Open in Word / LibreOffice / Google Docs.

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Generated by the PRISM engine v5_4_10.  https://lidarcloud.app
Draft data product - not a survey of record until reviewed, signed and sealed by a
licensed Professional Surveyor and Mapper.
