{"schema":1,"id":"ct-tower-bridge","title":"Tower Bridge context","evidence_class":"derived","source":{"dataset_id":"USGS_LPC_UT_Southern_QL1_2018_LAS_2019","acquired":"2018-04-27 / 2018-07-29 project interval","published":"2019-06-03","credit":"Map services and data available from U.S. Geological Survey, National Geospatial Program.","rights":"US Government Public Domain","packet":"assets/landmark-extensions/north/tower-bridge/profiles.json.gz","packet_sha256":"1798241e28462e30ab245072b1fc26ce2f99b7f7c752d7399bf921cce2c63a38","model":"assets/landmark-extensions/north/tower-bridge/model.json","model_sha256":"397fc6ebef3fa71b447d80c4c38bbb1bc3897c7623b3756522590f8a51a9ae1d","support_mesh":"assets/landmark-extensions/north/tower-bridge/small.glb.gz","support_mesh_sha256":"14acde8c605136dab9117a27cc806bf1ab67a3f6fce5e6cee8963bb3abba646d","grid_interval_m":4,"source_surface_cell_m":1,"height_encoding":"centimetres above base_m; encoding precision is not measurement accuracy","gap_policy":"Original row-segment mask; plan cells from conservative accepted small-mesh topology.","upstream_source_ids":["nps-tower","nps-pois","osm-locators"],"upstream_source_ledger":"assets/landmark-extensions/north/sources.json"},"row":72,"direction":"west-to-east","width_m":512,"sample_interval_m":4,"north_offset_m":-32,"surface_method":"upper-envelope","coordinates":{"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":2160,"center_utm":[398993.98793796386,4165613.1693918244],"bounds_utm":[398737.98793796386,4165357.1693918244,399249.98793796386,4165869.1693918244],"bounds_wgs84":[-112.1476666727532,37.62976483400713,-112.14179430652037,37.63443509841972],"vertical_exaggeration":1,"transform_note":"EPT projection transformed with pyproj; no claim of survey-grade datum alignment. Centimetre export quantization is not source accuracy."},"units":{"horizontal":"metres","vertical":"metres NAVD88 (Geoid12B), source heights retained"},"interpolation":"Linear within retained east-west segments only; no cross-row or gap interpolation.","points":[{"distance_m":0,"east_m":-256,"north_m":-32,"elevation_m":2268.39},{"distance_m":4,"east_m":-252,"north_m":-32,"elevation_m":2266.74},{"distance_m":8,"east_m":-248,"north_m":-32,"elevation_m":2264.71},{"distance_m":12,"east_m":-244,"north_m":-32,"elevation_m":2262.74},{"distance_m":16,"east_m":-240,"north_m":-32,"elevation_m":2260.61},{"distance_m":20,"east_m":-236,"north_m":-32,"elevation_m":2257.04},{"distance_m":24,"east_m":-232,"north_m":-32,"elevation_m":2253.99},{"distance_m":28,"east_m":-228,"north_m":-32,"elevation_m":2254.76},{"distance_m":32,"east_m":-224,"north_m":-32,"elevation_m":2257},{"distance_m":36,"east_m":-220,"north_m":-32,"elevation_m":2257.92},{"distance_m":40,"east_m":-216,"north_m":-32,"elevation_m":2256.46},{"distance_m":44,"east_m":-212,"north_m":-32,"elevation_m":2254.18},{"distance_m":48,"east_m":-208,"north_m":-32,"elevation_m":2254.17},{"distance_m":52,"east_m":-204,"north_m":-32,"elevation_m":2256.86},{"distance_m":56,"east_m":-200,"north_m":-32,"elevation_m":2264.5},{"distance_m":60,"east_m":-196,"north_m":-32,"elevation_m":2260.95},{"distance_m":64,"east_m":-192,"north_m":-32,"elevation_m":2256.53},{"distance_m":68,"east_m":-188,"north_m":-32,"elevation_m":2255.37},{"distance_m":72,"east_m":-184,"north_m":-32,"elevation_m":2254.28},{"distance_m":76,"east_m":-180,"north_m":-32,"elevation_m":2253.17},{"distance_m":80,"east_m":-176,"north_m":-32,"elevation_m":2252.12},{"distance_m":84,"east_m":-172,"north_m":-32,"elevation_m":2250.8},{"distance_m":88,"east_m":-168,"north_m":-32,"elevation_m":2246.13},{"distance_m":92,"east_m":-164,"north_m":-32,"elevation_m":2245.37},{"distance_m":96,"east_m":-160,"north_m":-32,"elevation_m":2248.75},{"distance_m":100,"east_m":-156,"north_m":-32,"elevation_m":2253.74},{"distance_m":104,"east_m":-152,"north_m":-32,"elevation_m":2258.3},{"distance_m":108,"east_m":-148,"north_m":-32,"elevation_m":2256.18},{"distance_m":112,"east_m":-144,"north_m":-32,"elevation_m":2257.03},{"distance_m":116,"east_m":-140,"north_m":-32,"elevation_m":2258.14},{"distance_m":120,"east_m":-136,"north_m":-32,"elevation_m":2257.12},{"distance_m":124,"east_m":-132,"north_m":-32,"elevation_m":2254.05},{"distance_m":128,"east_m":-128,"north_m":-32,"elevation_m":2251.44},{"distance_m":132,"east_m":-124,"north_m":-32,"elevation_m":2248.24},{"distance_m":136,"east_m":-120,"north_m":-32,"elevation_m":2245.62},{"distance_m":140,"east_m":-116,"north_m":-32,"elevation_m":2243.19},{"distance_m":144,"east_m":-112,"north_m":-32,"elevation_m":2242.37},{"distance_m":148,"east_m":-108,"north_m":-32,"elevation_m":2241.43},{"distance_m":152,"east_m":-104,"north_m":-32,"elevation_m":2239.22},{"distance_m":156,"east_m":-100,"north_m":-32,"elevation_m":2237.77},{"distance_m":160,"east_m":-96,"north_m":-32,"elevation_m":2236.33},{"distance_m":164,"east_m":-92,"north_m":-32,"elevation_m":2233.82},{"distance_m":168,"east_m":-88,"north_m":-32,"elevation_m":2231.1},{"distance_m":172,"east_m":-84,"north_m":-32,"elevation_m":null},{"distance_m":176,"east_m":-80,"north_m":-32,"elevation_m":null},{"distance_m":180,"east_m":-76,"north_m":-32,"elevation_m":null},{"distance_m":184,"east_m":-72,"north_m":-32,"elevation_m":null},{"distance_m":188,"east_m":-68,"north_m":-32,"elevation_m":null},{"distance_m":192,"east_m":-64,"north_m":-32,"elevation_m":null},{"distance_m":196,"east_m":-60,"north_m":-32,"elevation_m":null},{"distance_m":200,"east_m":-56,"north_m":-32,"elevation_m":null},{"distance_m":204,"east_m":-52,"north_m":-32,"elevation_m":null},{"distance_m":208,"east_m":-48,"north_m":-32,"elevation_m":null},{"distance_m":212,"east_m":-44,"north_m":-32,"elevation_m":null},{"distance_m":216,"east_m":-40,"north_m":-32,"elevation_m":null},{"distance_m":220,"east_m":-36,"north_m":-32,"elevation_m":null},{"distance_m":224,"east_m":-32,"north_m":-32,"elevation_m":null},{"distance_m":228,"east_m":-28,"north_m":-32,"elevation_m":null},{"distance_m":232,"east_m":-24,"north_m":-32,"elevation_m":null},{"distance_m":236,"east_m":-20,"north_m":-32,"elevation_m":null},{"distance_m":240,"east_m":-16,"north_m":-32,"elevation_m":null},{"distance_m":244,"east_m":-12,"north_m":-32,"elevation_m":null},{"distance_m":248,"east_m":-8,"north_m":-32,"elevation_m":null},{"distance_m":252,"east_m":-4,"north_m":-32,"elevation_m":null},{"distance_m":256,"east_m":0,"north_m":-32,"elevation_m":null},{"distance_m":260,"east_m":4,"north_m":-32,"elevation_m":null},{"distance_m":264,"east_m":8,"north_m":-32,"elevation_m":null},{"distance_m":268,"east_m":12,"north_m":-32,"elevation_m":null},{"distance_m":272,"east_m":16,"north_m":-32,"elevation_m":null},{"distance_m":276,"east_m":20,"north_m":-32,"elevation_m":null},{"distance_m":280,"east_m":24,"north_m":-32,"elevation_m":null},{"distance_m":284,"east_m":28,"north_m":-32,"elevation_m":null},{"distance_m":288,"east_m":32,"north_m":-32,"elevation_m":null},{"distance_m":292,"east_m":36,"north_m":-32,"elevation_m":null},{"distance_m":296,"east_m":40,"north_m":-32,"elevation_m":null},{"distance_m":300,"east_m":44,"north_m":-32,"elevation_m":null},{"distance_m":304,"east_m":48,"north_m":-32,"elevation_m":null},{"distance_m":308,"east_m":52,"north_m":-32,"elevation_m":null},{"distance_m":312,"east_m":56,"north_m":-32,"elevation_m":2190.88},{"distance_m":316,"east_m":60,"north_m":-32,"elevation_m":2190.68},{"distance_m":320,"east_m":64,"north_m":-32,"elevation_m":2193.4},{"distance_m":324,"east_m":68,"north_m":-32,"elevation_m":2195.8},{"distance_m":328,"east_m":72,"north_m":-32,"elevation_m":2195.04},{"distance_m":332,"east_m":76,"north_m":-32,"elevation_m":2195.51},{"distance_m":336,"east_m":80,"north_m":-32,"elevation_m":2195.92},{"distance_m":340,"east_m":84,"north_m":-32,"elevation_m":2196.01},{"distance_m":344,"east_m":88,"north_m":-32,"elevation_m":2195.82},{"distance_m":348,"east_m":92,"north_m":-32,"elevation_m":2195.84},{"distance_m":352,"east_m":96,"north_m":-32,"elevation_m":2196.12},{"distance_m":356,"east_m":100,"north_m":-32,"elevation_m":2196.17},{"distance_m":360,"east_m":104,"north_m":-32,"elevation_m":2196.13},{"distance_m":364,"east_m":108,"north_m":-32,"elevation_m":2196.07},{"distance_m":368,"east_m":112,"north_m":-32,"elevation_m":2195.9},{"distance_m":372,"east_m":116,"north_m":-32,"elevation_m":2195.96},{"distance_m":376,"east_m":120,"north_m":-32,"elevation_m":2197.02},{"distance_m":380,"east_m":124,"north_m":-32,"elevation_m":2198.47},{"distance_m":384,"east_m":128,"north_m":-32,"elevation_m":2199.99},{"distance_m":388,"east_m":132,"north_m":-32,"elevation_m":2201.52},{"distance_m":392,"east_m":136,"north_m":-32,"elevation_m":2212.86},{"distance_m":396,"east_m":140,"north_m":-32,"elevation_m":2204.18},{"distance_m":400,"east_m":144,"north_m":-32,"elevation_m":2205.36},{"distance_m":404,"east_m":148,"north_m":-32,"elevation_m":2206.57},{"distance_m":408,"east_m":152,"north_m":-32,"elevation_m":2208.69},{"distance_m":412,"east_m":156,"north_m":-32,"elevation_m":2207.88},{"distance_m":416,"east_m":160,"north_m":-32,"elevation_m":2207.99},{"distance_m":420,"east_m":164,"north_m":-32,"elevation_m":2208.29},{"distance_m":424,"east_m":168,"north_m":-32,"elevation_m":2207.34},{"distance_m":428,"east_m":172,"north_m":-32,"elevation_m":2207.94},{"distance_m":432,"east_m":176,"north_m":-32,"elevation_m":2208.63},{"distance_m":436,"east_m":180,"north_m":-32,"elevation_m":2209.4},{"distance_m":440,"east_m":184,"north_m":-32,"elevation_m":2209.8},{"distance_m":444,"east_m":188,"north_m":-32,"elevation_m":2210.35},{"distance_m":448,"east_m":192,"north_m":-32,"elevation_m":2214.53},{"distance_m":452,"east_m":196,"north_m":-32,"elevation_m":2216.63},{"distance_m":456,"east_m":200,"north_m":-32,"elevation_m":2211.13},{"distance_m":460,"east_m":204,"north_m":-32,"elevation_m":2211.29},{"distance_m":464,"east_m":208,"north_m":-32,"elevation_m":2210.45},{"distance_m":468,"east_m":212,"north_m":-32,"elevation_m":2208.6},{"distance_m":472,"east_m":216,"north_m":-32,"elevation_m":2205.81},{"distance_m":476,"east_m":220,"north_m":-32,"elevation_m":2202.37},{"distance_m":480,"east_m":224,"north_m":-32,"elevation_m":2198.99},{"distance_m":484,"east_m":228,"north_m":-32,"elevation_m":2196.23},{"distance_m":488,"east_m":232,"north_m":-32,"elevation_m":2194.04},{"distance_m":492,"east_m":236,"north_m":-32,"elevation_m":2192.27},{"distance_m":496,"east_m":240,"north_m":-32,"elevation_m":2190.72},{"distance_m":500,"east_m":244,"north_m":-32,"elevation_m":2189.72},{"distance_m":504,"east_m":248,"north_m":-32,"elevation_m":2192.24},{"distance_m":508,"east_m":252,"north_m":-32,"elevation_m":2194.06},{"distance_m":512,"east_m":256,"north_m":-32,"elevation_m":2195.38}],"segments_supported":[1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1],"gap_mask":[{"start_m":168,"end_m":312,"reason":"source-omission-or-conservative-support-mask"}],"statistics":{"min_m":2189.72,"max_m":2268.39,"relief_m":78.67000000000007,"retained_length_m":368,"retained_fraction":0.71875,"gap_intervals":1},"limits":["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.","This is a topographic section, not stratigraphy, a safe route or surveyed trail ascent.","Coarse packet spacing cannot resolve every feature between nodes. No new ground scan is supplied."],"question":"What can a blank interval tell you about the limits of a model?","reading":"The source deliberately omits a footprint around unresolved arch, pillar and underside geometry. The hatched interval is withheld data, not a measured opening. Neither the plan nor the section fills this gap.","display":{"vertical_exaggeration":1,"datum":"relative"}}