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"start_distance_m": 1557.0, "end_distance_m": 1560.0, "midpoint_distance_m": 1558.5, "start_elevation_m": 172.47189425031343, "end_elevation_m": 173.47434915892, "start_xy": [ 313045.32064895594, 240803.08563600056 ], "end_xy": [ 313045.62699513056, 240806.06995368158 ] } }, "diagnostic_note": "Windows <=3 m are at raster-noise scale (1-sigma raster noise alone is roughly +/-7 pp at 2 m and +/-5 pp at 3 m on a 1 m DTM). Diagnostic use only: never a headline or ranking value.", "quality_summary": { "overhead_obstruction": { "obstruction_threshold_m": 2.0, "obstructed_fraction": 0.116, "obstruction_max_height_m": 16.91, "flagged_windows_m": [] }, "structure_suppression": { "masked_fraction": 0.001, "windows_resited": [ 2.0 ], "windows_unresolved": [] }, "excluded_ranges_m": [ [ 1608.0, 1613.0 ] ], "review": [], "extent": [] }, "provenance": { "analysis_version": "0.1.0", "sample_interval_m": 1.0, "interpolation": "bilinear", "smoothing": "none", "gradient_windows_m": [ 5.0, 10.0, 20.0, 25.0, 50.0, 100.0 ], "diagnostic_windows_m": [ 2.0, 3.0 ], "elevation_crs": "EPSG:27700", "elevation_resolution_m": 1.0, "elevation_tiles": [ "data/cache/wales/dtm_1m/wg_del_16_312239_20210329dtm.tif", "data/cache/wales/dtm_1m/wg_del_16_312240_20210329dtm.tif", "data/cache/wales/dtm_1m/wg_del_16_312241_20210329dtm.tif", "data/cache/wales/dtm_1m/wg_del_16_312242_20210329dtm.tif", "data/cache/wales/dtm_1m/wg_del_16_312243_20210329dtm.tif", "data/cache/wales/dtm_1m/wg_del_16_313239_20210329dtm.tif", "data/cache/wales/dtm_1m/wg_del_16_313240_20210329dtm.tif", "data/cache/wales/dtm_1m/wg_del_16_313241_20210329dtm.tif", "data/cache/wales/dtm_1m/wg_del_16_313242_20210329dtm.tif", "data/cache/wales/dtm_1m/wg_del_16_313243_20210329dtm.tif" ], "calculated_at": "2026-08-12T09:07:51+00:00", "road_source": "OpenStreetMap (local PBF extract)", "road_attribution": "\u00a9 OpenStreetMap contributors, ODbL", "osm_pbf_path": "data/cache/pbf/wales-2026-08-11.osm.pbf", "osm_snapshot": "2026-08-10T20:21:40Z", "elevation_provider": "Welsh Government", "elevation_dataset": "Welsh Government LiDAR 1m DTM (2020-2023)", "elevation_licence": "Open Government Licence v3 \u2014 \u00a9 Crown copyright Welsh Government", "elevation_catalogue_layer": "geonode:welsh_government_lidar_tile_catalogue_2020_2023", "elevation_tile_ids": [ "wg_del_16_312239_20210329dtm.tif", "wg_del_16_312240_20210329dtm.tif", "wg_del_16_312241_20210329dtm.tif", "wg_del_16_312242_20210329dtm.tif", "wg_del_16_312243_20210329dtm.tif", "wg_del_16_313239_20210329dtm.tif", "wg_del_16_313240_20210329dtm.tif", "wg_del_16_313241_20210329dtm.tif", "wg_del_16_313242_20210329dtm.tif", "wg_del_16_313243_20210329dtm.tif" ], "elevation_capture_dates": [ "30-03-2021" ], "climb_origin": "discovered", "notes": "Coarse pass: max 13.7% over 200 m (Terrain 50), gain 227.6 m over 4355 m way. EXTENDED by graph walk: +1 segment(s) at base, +0 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. ADOPTED (notable slice 2026-08-11): clean-steep. AUTO-NAMED from gazetteer (hypothesis, unreviewed): was 'Discovered lane (52.0653, -3.2641)'.", "naming_note": "auto-named from gazetteer (hypothesis, unreviewed); discovered as 'Discovered lane (52.0653, -3.2641)'" }, "area": { "place": "Llanstephan", "county": "Powys - Powys" }, "reported_claims": [], "confidence": "A", "shape": { "ascent_concentration": 0.419, "concentration_window_frac": 0.25, "longest_pitch_10pct_m": 124.0, "shape_class": "sustained" } }