elevation used as absolute Z · not parish-clippedelevation used as absolute Z · not parish-clippedDesigned by Ben Sumpter. This provisional standalone build covers the supplied Breage, Helston, Sithney and Wendron civil-parish study area and associated mine workings. The core model uses British National Grid (EPSG:27700) with elevations in metres OD.
SRTMGL3.tiff, used as the provisional surface and resampled to a compact parish-clipped display grid. The higher-resolution LiDAR replacement is deferred until a suitably compressed form is prepared.Treworlis & Tremenheere.gpkg. The supplied elevation attribute is assigned as absolute Z to every source plan vertex; levels are never DTM-draped and are not parish-clipped.Adits_Elevation.gpkg. The supplied elevation attribute is the project Z convention; adits are never DTM-draped and are not parish-clipped.Shafts_Draped.gpkg. Existing Point Z is preserved verbatim while XY is reprojected from WGS84 to EPSG:27700. No underground shaft trace is inferred from a collar point.Helston parishes.gpkg, four supplied civil-parish polygons. The boundary line is surface-draped to the provisional SRTM.road.gpkg, waterways.gpkg, Buildings.gpkg and places.gpkg. These OpenStreetMap-derived WGS84 layers are reprojected to EPSG:27700, clipped to the four-parish study area, densified where linear, and sampled from the same rendered SRTM surface. Tiny cartographic lifts (0.22–0.55 m) prevent z-fighting. The supplied place elevation/Z is retained for inspection as source_elevation, while the rendered point is explicitly terrain-draped. Road features tagged as bridge or tunnel are shown as surface-projected context because the supplied source has no authoritative vertical geometry from which to reconstruct their true deck/tunnel elevation.625k_V5_Geology_UK_EPSG27700.gpkg. Bedrock and dyke polygons use the colours embedded in the supplied QGIS styles and are rasterised only as the regional display overlay, then mapped directly onto the WebGL terrain surface. Superficial deposits are a separate terrain-draped overlay. Faults remain vector lines, densified to 45 m or less and sampled from the rendered SRTM terrain; a 0.35 m cartographic lift prevents z-fighting without changing their plan position.MAX_TIME_Y and MIN_TIME_Y fields are converted from years to Ma for the dual-handle filter. The supplied superficial/fault records do not provide directly usable absolute Ma bounds, so no absolute ages are invented for them.Franchise Lode.gpkg remains excluded until its authoritative elevation/datum rule is specified.The source GIS files were supplied for this project. Roads, waterways, buildings and places are OpenStreetMap-derived data; © OpenStreetMap contributors, Open Database Licence (ODbL). The regional geology is the supplied BGS 1:625,000 V5 GeoPackage (bedrock/dykes/faults release 5.17; superficial layer version 1.10 as encoded in the source attributes). Publication/licensing terms should still be confirmed before public release. SRTM is a coarse provisional terrain source and is not a substitute for the planned LiDAR surface. Underground mine geometry reflects plan/source elevations and should not be interpreted as terrain-constrained geometry.
Shaft-collar Z is observed/source geometry and is retained exactly. Mine-level and adit Z is derived directly from each source feature's authoritative elevation attribute. Parish-boundary Z and all added roads, waterways, building footprints and place display points are derived from the provisional SRTM surface; the source place elevation is retained separately as metadata. No underground working is draped to the DTM.
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