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219212.7180040248 ], "end_xy": [ 269197.5706371622, 219129.1301097081 ] } }, "diagnostic_window_maxima": { "max_2m": { "gradient_pct": 52.88472318334527, "start_distance_m": 1298.0, "end_distance_m": 1300.0, "midpoint_distance_m": 1299.0, "start_elevation_m": 255.9671368757132, "end_elevation_m": 257.0248313393801, "start_xy": [ 269531.00145346124, 219515.1040048652 ], "end_xy": [ 269530.5094542806, 219513.1654650007 ] }, "max_3m": { "gradient_pct": 43.560620983293084, "start_distance_m": 1297.0, "end_distance_m": 1300.0, "midpoint_distance_m": 1298.5, "start_elevation_m": 255.71801270988132, "end_elevation_m": 257.0248313393801, "start_xy": [ 269531.2474530516, 219516.07327479744 ], "end_xy": [ 269530.5094542806, 219513.1654650007 ] } }, "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": 0.241, "obstruction_max_height_m": 22.25, "flagged_windows_m": [ 2, 3, 5, 20, 25, 50, 100 ] }, "structure_suppression": { "masked_fraction": 0.015, "windows_resited": [ 2.0, 3.0, 5.0, 100.0 ], "windows_unresolved": [] }, "no_bench_suppression": { "masked_fraction": 0.054, "windows_resited": [], "windows_unresolved": [] }, "excluded_ranges_m": [ [ 51.0, 56.0 ], [ 85.0, 90.0 ], [ 419.0, 424.0 ], [ 426.0, 431.0 ], [ 650.0, 730.0 ], [ 860.0, 890.0 ], [ 1024.0, 1030.0 ], [ 1309.0, 1314.0 ], [ 1839.0, 1845.0 ] ], "review": [], "extent": [ "may_start_earlier", "descends_at_end" ] }, "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_21_268218_20220113dtm.tif", "data/cache/wales/dtm_1m/wg_del_21_268219_20220113dtm.tif", "data/cache/wales/dtm_1m/wg_del_21_268220_20220113dtm.tif", "data/cache/wales/dtm_1m/wg_del_21_269218_20220113dtm.tif", "data/cache/wales/dtm_1m/wg_del_21_269219_20220113dtm.tif", "data/cache/wales/dtm_1m/wg_del_21_269220_20220113dtm.tif", "data/cache/wales/dtm_1m/wg_del_21_270218_20220113dtm.tif", "data/cache/wales/dtm_1m/wg_del_21_270219_20220113dtm.tif", "data/cache/wales/dtm_1m/wg_del_21_270220_20220113dtm.tif" ], "calculated_at": "2026-08-12T09:07:21+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_21_268218_20220113dtm.tif", "wg_del_21_268219_20220113dtm.tif", "wg_del_21_268220_20220113dtm.tif", "wg_del_21_269218_20220113dtm.tif", "wg_del_21_269219_20220113dtm.tif", "wg_del_21_269220_20220113dtm.tif", "wg_del_21_270218_20220113dtm.tif", "wg_del_21_270219_20220113dtm.tif", "wg_del_21_270220_20220113dtm.tif" ], "elevation_capture_dates": [ "13-01-2022" ], "climb_origin": "discovered", "notes": "Coarse pass: max 15.1% over 200 m (Terrain 50), gain 24.1 m over 1540 m way. EXTENDED by graph walk: +2 segment(s) at base, +2 at top (stop: base=no_descending_continuation, top=no_ascending_continuation; min_avg=2.0%). Review before adopting. ADOPTED (notable slice 2026-08-11): qualified-steep. AUTO-NAMED from gazetteer (hypothesis, unreviewed): was 'Discovered lane (51.8611, -3.8938)'.", "naming_note": "auto-named from gazetteer (hypothesis, unreviewed); discovered as 'Discovered lane (51.8611, -3.8938)'" }, "area": { "place": "Glyn Llydan", "county": "Sir Gaerfyrddin - Carmarthenshire" }, "reported_claims": [], "confidence": "B", "shape": { "ascent_concentration": 0.368, "concentration_window_frac": 0.25, "longest_pitch_10pct_m": 80.0, "shape_class": "sustained" } }