{ "id": "china-wall", "name": "China Wall", "alternate_names": [ "Chinese Wall" ], "center": [ -112.1535390112869, 37.63332185329902 ], "width_m": 512, "priority": 1, "source_ids": [ "gnis-north", "nps-china-archive", "usgs-geology" ], "question": "When does a wall begin to read as separate towers?", "theme": "A ridge narrowed into a wall", "view_yaw": 0.75, "view_pitch": 0.58, "locator": { "source_id": "gnis-north", "feature_id": 1439695, "official_name": "Chinese Wall", "role": "cliff name locator" }, "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", "coordinate_system": { "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", "units": "metres", "axes": "x east, y up from base_m, z south", "base_m": 2230, "center_utm": [ 398218.3944254437, 4165758.2548199575 ], "bounds_utm": [ 397962.3944254437, 4165502.2548199575, 398474.3944254437, 4166014.2548199575 ], "bounds_wgs84": [ -112.15647559644214, 37.630986477595876, -112.15060260541384, 37.63565716146209 ], "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": 7212433, "density_returns_per_m2": 27.513, "ground_returns": 3133723, "retained_returns": 6167762, "vegetation_candidate_returns": 1044671, "excluded_noise_or_other": 3105, "directly_observed_node_fraction": 0.9991374364001839, "interpolated_node_fraction": 0.0008625635998160878, "unsupported_node_fraction": 0.0, "isolated_high_cells_repaired": 29, "maximum_nearest_fill_m": 3.0, "cell_m": 1.0, "source_heights_m": [ 2193.090087890625, 2368.360107421875 ], "surface_heights_m": [ 2246.02001953125, 2368.360107421875 ], "intensity_display_percentiles": [ 5392.0, 12704.0 ], "vertical_surfaces": "An upper envelope can join returns across a steep face; it cannot recover undercuts, windows, or unseen interiors.", "surface_method": "upper-envelope", "editorial_exclusion_node_fraction": 0.0, "unsupported_or_excluded_node_fraction": 0.0 }, "levels": [ { "file": "small.glb.gz", "bytes": 422708, "uncompressed_bytes": 1127308, "sha256": "0bd6ff16b006cd63fb8ceaab961c567e59442403304a26533d9b1268a0910955", "id": "small", "vertices": 16641, "triangles": 32768, "grid_nodes": 129, "spacing_m": 4.0, "degenerate_triangles": 0, "downward_triangles": 0 }, { "file": "balanced.glb.gz", "bytes": 1608019, "uncompressed_bytes": 4480904, "sha256": "d7a7306211e0e676dd6d54281bf5a7edf47ad5d5ee063f26c4617a023405c7ce", "id": "balanced", "vertices": 66049, "triangles": 131072, "grid_nodes": 257, "spacing_m": 2.0, "degenerate_triangles": 0, "downward_triangles": 0 }, { "file": "detailed.glb.gz", "bytes": 6272154, "uncompressed_bytes": 17872792, "sha256": "01e0b603eeb720ad6da2c73fd3bf4651d975cb063e03c708afd6a94f3f7c2586", "id": "detailed", "vertices": 263169, "triangles": 524288, "grid_nodes": 513, "spacing_m": 1.0, "degenerate_triangles": 0, "downward_triangles": 0 } ], "returns": { "file": "returns.glb.gz", "bytes": 1211848, "uncompressed_bytes": 2881240, "sha256": "92a9333e3206c3e9c4a4ab4cd1814ee2edd6c42bc9b33cd570bae28baddb283f", "count": 120000, "sampling": "fixed seed 20261002, uniform without replacement from valid crop returns" }, "profiles": "profiles.json.gz", "camera": { "yaw": 0.75, "pitch": 0.58, "distance_m": 1018.9092486022333, "target": [ 0, 66.8701171875, 0 ], "minimum_distance_ratio": 0.85, "useful_range_note": "Landscape inspection only; camera is not permitted to approach a ground-walk distance.", "reference_viewport": [ 1400, 1050 ], "vertical_fov_degrees": 38, "fit_method": "Runtime projects actual active vertices to fit the viewport with a 14 percent frame margin; distance_m records the poster reference view.", "closest_reviewed_distance_ratio": 0.85 }, "bounds_local": [ [ -256.0, 16.02001953125, -256.0 ], [ 256.0, 138.360107421875, 256.0 ] ], "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.", "exclusions": "Elliptical uncertainty masks remove the entire plan footprint around unresolved arch/alcove geometry; all LODs conservatively preserve these holes. They are not measured opening outlines." }, "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_local_educational_landscape", "exclusions": [], "source_acquisition": { "path": "acquisition.json", "points_sha256": "6bd061e69a018c1e403d250572836d88e9d10d9fbf97716cc1afe6227bfa9252", "source_object_count": 253 }, "editorial": { "lede": "A long, narrow ridge makes the transition from wall to separate towers legible.", "body": "NPS archives call this feature China Wall; the USGS geographic names record uses Chinese Wall. The study preserves both names. USGS describes Bryce’s thin divides as remnants between eroding gullies. Here, viewing across the ridge and along it reveals very different silhouettes.", "lesson": "Switch between the reconstructed surface and measured returns. A broad ridge is better constrained than a thin crest. The historical NPS photograph provides an independent view of the feature; it supplies neither hidden geometry nor a calibrated change measurement.", "limit": "A narrow fin can be broadened by grid sampling, and gaps beneath a crest remain unresolved. The historical photograph is a separate reference, never a model texture or evidence of a measured erosion rate.", "caption": "The China Wall landscape study. Thin crests are limited by the grid and the airborne view.", "evidence_title": "Follow the wall, then cross it", "evidence_note": "A thin ridge can look continuous from one angle and broken from another. Returns and the source photograph help expose the limits of the surface.", "annotation_title": "China Wall / Chinese Wall", "annotation_text": "Published USGS cliff locator, GNIS 1439695. NPS’s archive uses China Wall. Neither point nor title provides a surveyed wall boundary." }, "imagery": { "publisher": "USDA Farm Service Agency / FPAC", "dataset": "National Agriculture Imagery Program (NAIP), Utah 2024", "retrieved_at": "2026-10-02T09:27:34.900549+00:00", "source_pixels_m": 0.6, "export_pixels": 854, "export_pixel_m": 0.5995316159250585, "crs": "EPSG:32612", "requested_bounds": [ 397962.3944254437, 4165502.2548199575, 398474.3944254437, 4166014.2548199575 ], "export_extent": { "xmin": 397962.3944254437, "ymin": 4165502.2548199575, "xmax": 398474.3944254437, "ymax": 4166014.2548199575, "spatialReference": { "wkid": 32612, "latestWkid": 32612 } }, "flight_dates": [ "2024-07-23" ], "images": [ { "OBJECTID": 195984, "Name": "m_3711223_se_12_060_20240723", "Category": 1, "year_ts": 2024, "ST": "UT", "QQNAME": "3711223SE060", "QQDATE": 1721692800000, "iDate_ts": 1749744257170 } ], "catalog_url": "https://apps.geo.fpac.usda.gov/geo-imagery/rest/services/naip/conus_naip/ImageServer/query?f=json&geometry=%7B%22xmin%22%3A397962.3944254437%2C%22ymin%22%3A4165502.2548199575%2C%22xmax%22%3A398474.3944254437%2C%22ymax%22%3A4166014.2548199575%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=397962.3944254437%2C4165502.2548199575%2C398474.3944254437%2C4166014.2548199575&bboxSR=32612&imageSR=32612&size=854%2C854&format=png&pixelType=U8&interpolation=RSP_BilinearInterpolation&adjustAspectRatio=false&bandIds=0%2C1%2C2&mosaicRule=%7B%22mosaicMethod%22%3A%22esriMosaicLockRaster%22%2C%22lockRasterIds%22%3A%5B195984%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=397962.3944254437%2C4165502.2548199575%2C398474.3944254437%2C4166014.2548199575&bboxSR=32612&imageSR=32612&size=854%2C854&format=png&pixelType=U8&interpolation=RSP_BilinearInterpolation&adjustAspectRatio=false&bandIds=0%2C1%2C2&mosaicRule=%7B%22mosaicMethod%22%3A%22esriMosaicLockRaster%22%2C%22lockRasterIds%22%3A%5B195984%5D%2C%22mosaicOperation%22%3A%22MT_FIRST%22%7D", "original_sha256": "c5492ba9e722c6978a73bef136207a83c8933ebd1594d4079013723a852330e1", "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 from a different year than the 2018 topography; acquisition shadows, tree crowns and metre-scale registration error remain. Displayed only in the overhead evidence view, never as a wall photograph." }, "sources": [ { "id": "gnis-north", "title": "USGS geographic names: northern Bryce landforms", "publisher": "US Geological Survey / National Geospatial Program", "url": "https://carto.nationalmap.gov/arcgis/rest/services/geonames/MapServer/5", "date": null, "rights": "US Government Public Domain", "supports": "Official names and published locators for Boat Mesa, Sinking Ship, Chinese Wall, Bristlecone Point and audited alternatives. Name points are not surveyed feature boundaries.", "evidence": "gnis-north-landforms.json" }, { "id": "nps-china-archive", "title": "China Wall from Fairyland Loop: archival photograph", "publisher": "Bryce Canyon National Park Museum and Archives", "author": "Maurice Cope", "url": "https://npgallery.nps.gov/AssetDetail/855691eb110f4d85aa4e4e0c8671f28d", "date": null, "rights": "Public domain; mandatory credit: Courtesy Bryce Canyon National Park, Photographer Maurice Cope, Museum Catalog Number BRCA 532/001-#191", "supports": "Independent oblique reference and NPS name China Wall. Capture date and camera calibration are not established; not used for mesh geometry, texture or change-rate measurement.", "evidence": "nps-china-archive.html" }, { "id": "usgs-geology", "title": "Geologic map of Bryce Canyon National Park and vicinity: explanatory report", "publisher": "US Geological Survey", "author": "W. E. Bowers", "url": "https://pubs.usgs.gov/imap/2108/report.pdf", "date": "1990", "rights": "US Government Public Domain", "supports": "Thin divides, ridges and hoodoos between eroding gullies; named Chinese Wall and Tower Bridge. Historical numerical erosion estimates are not used in this product." } ], "annotations": [ { "title": "China Wall / Chinese Wall", "text": "Published USGS cliff locator, GNIS 1439695. NPS’s archive uses China Wall. Neither point nor title provides a surveyed wall boundary.", "position": [ 0.0, 87.8701171875, 0.0 ], "anchor_surface_elevation_navd88_m": 2312.8701171875, "display_lift_m": 5, "coordinate_source": { "source_id": "gnis-north", "feature_id": 1439695, "official_name": "Chinese Wall", "role": "cliff name locator" }, "height_method": "Nearest fine-grid sample at published locator; display lift is illustrative; no surveyed feature elevation asserted" } ], "static_profile": { "row": 64, "direction": "west to east", "north_offset_m": 0, "minimum_m": 2272.1, "maximum_m": 2325.93, "vertical_exaggeration": 1, "source": "profiles.json.gz" }, "source_coordinate_check": "source-coordinate-check.json", "textures": [ { "file": "aerial.webp", "bytes": 223338, "sha256": "0ed3b8629a3602fe4c2e1714da887fe6c629f7eeb3b6355e15643a2b66e13619", "role": "separate overhead evidence image, never wall texture" }, { "file": "aerial-small.webp", "bytes": 79866, "sha256": "9e5677677cf1a4a14b8ffe9bdeaf04bb0b6ac249f90c9fd82a8c34ac859ea29e", "role": "separate overhead evidence image, never wall texture" } ], "quality_record": "quality.json" }