# SigInfo 3D Mast — Emley Moor

Third site, added 3 October 2026. Source origin: OSM tower footprint centroid rounded to E422296 N412887, EPSG:27700. 3 km analysis radius; 6.2 km square landscape. True vertical scale.

## Tower evidence

- Historic England, NHLE 1350339: https://historicengland.org.uk/listing/the-list/list-entry/1350339 — concrete shaft 274 m, 24.4 m base diameter and 6.5 m upper diameter, exponential taper, 56 m aerial casing; model heritage total 330 m. Built 1969–71, Ove Arup and Partners.
- Arqiva: https://www.arqiva.com/news/end-of-an-era-emley-moor — 6 September 2023 report describes return to main tower and dismantling of temporary mast. Quotes 330.4 m overall.
- OSM way 476925020: https://www.openstreetmap.org/way/476925020 — records 330.5 m. Retrieved 3 October 2026.
- Later antenna alterations mean this is explicitly a heritage envelope, not a claim of current as-built height. Gallery position, diameters, windows, collars, joints, lights and aerial taper are approximate. The temporary mast is omitted from the rendered structures. Historic DSM may still register removed objects.

## Landscape

Environment Agency 1 m WCS DTM, first-return DSM and Vegetation Object Model downloaded 3 October 2026, bounds E419196–425396, N409787–415987. Data is a historic composite; the local acquisition date has not been isolated. It does not represent live 2026 conditions.

The reproducible requests are in research/emley/download.py, with coverage identifiers in the accompanying capabilities XML and raw-grid SHA256 hashes. Run download.py and fetch-osm.py then process.py with rasterio, pyproj, shapely, scipy, numpy and Pillow. Raw native rasters are not bundled in the site.

Terrain display: bilinear 20 m vertices, no vertical exaggeration. Ground analysis: 5 m mean DTM cells; surface analysis: 5 m maximum first-return DSM cells. Metres ODN stored as Int16 decimetres; -32768 is unknown. 100% of this downloaded surface grid is populated. Sample every <=2.5 m, excluding first 20 m source compound and exact endpoint. Clear means only no sampled geometric obstruction; no Fresnel, refraction, radio coverage or structural assessment.

OSM roads, landcover and 9251 building footprints. Building heights use 85th-percentile DSM minus DTM in footprint, with assumed storey fallback tagged per feature. Flat roofs and centroid base levels are simplifications. 30739 canopy volumes represent 10 m inner and 20 m outer vegetation cells, not individual trees. Texture is synthetic mapped landcover and hillshade, not aerial photography. Survey structures may have changed or been removed.

## Licences

Contains Environment Agency information © Environment Agency and/or database right, licensed under Open Government Licence v3.0. https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/

Map features © OpenStreetMap contributors, Open Database Licence: https://www.openstreetmap.org/copyright . OSM-derived processed features are provided in features.json and raw source in research/emley/osm.json.

Three.js MIT (see THREE-LICENSE.txt).

## Equipment detail update

The new equipment layer combines dated engineering evidence with representative geometry. Arup Journal March 1972 documents three 3.66 m dishes at about 30.5 m; 2011 MarksPictures photographs show the lower dish ring and upper arrays. Ofcom’s radio workbook, page dated 5 August 2026, supplies 305 m FM and 285/271 m DAB aerial heights. The reconstructed dish ring count, bearings, platform dimensions and current physical arrangement are estimates, not a current survey. No equipment owner is inferred from a dish position. Tap equipment for its status, or open the site dossier.

The terrain extension adds 2 km to the previous 1 km radius. Downloaded in four 3100 m tiles per layer; mosaicked without resampling on the native 1 m grid. Surface profiles retain 5 m cells.