# Coordinate and reconstruction validation — Arkle version0002

Cutoff: 30 September 2026. No geographically registered exploration overlay is approved in this package.

| Layer | Frame and controls | Result | Limitation |
|---|---|---|---|
| September ULG plan | Original 476×416 raster; grid ticks 493000 at x 31, 493500 at 157, 494000 at 283; holdout 494500 at 409. Northing ticks approximately 7546000 at y 67, 7545500 at 194, 7545000 at 320. | Internal scale about 3.97 m/pixel. Linear spacing closes to within roughly 1 px. Native features use original pixels directly, with no fitted geographic shift. | Tick checks are internal, not independent surveyed controls. CRS/datum unspecified; no WGS 84/UTM assumption. |
| May regional / HLEM plans | Separate original rasters, visible headings and manually recovered line endpoints | Source-local; no cross-vintage transform | Datum, flight-line geometry and numerical inversion unavailable. Conductivity paths are not mineralised solids. |
| 8298/7986 target waypoints | Published lat/long tables; relative positions centred per licence using 111320 m/degree and cos(latitude) | Original coordinates retained; approximate local metres only | No declared table datum, survey precision or RL. Not collars or assays. |
| 8995 grant appendix | Bessel 1841 spheroid, Albers Conic Equal Area, central meridian 17°E; historical DMS appendix | Source retained; excluded from current geographic overlay | Complete transformation and independent controls absent; notice is conditional, not current title. |
| 8995 December 2023 map | Stated GCS WGS 1984, centre 14.921229 E /22.22888 S | Centre corroborates regional terrain context location | A labelled map centre is not a surveyed control or legal footprint. |
| Bundled terrain + satellite | Copernicus GLO 30 EPSG 4326 / EGM 2008; Sentinel-2 tile EPSG 32733; commonUTM 33 S bounds | Product georeferencing aligned for context; no exploration geometry on terrain | Provider geolocation, not a ground survey. Independent local ground-control accuracy remains unverified. |

The viewer uses true horizontal and vertical metres for terrain, with a constant elevation-origin translation only (vertical exaggeration 1). The local mesh is bilinearly resampled to 160×160; native Sentinel 10 m crop is retained separately from the 1024 px display texture. Elevation acquisition is the product period 2011–2015, not capture date. Sentinel acquisition is 2026-09-30 T09:16:46.545Z; local SCL classes 4/5/6 cover 100% of the selected crop. Clear-class coverage is not a guarantee of zero atmospheric effects.

The ULG reconstruction retains a conservative subset of 20 colour-supported marks, nine approximate collar-symbol associations,9 visible trench strokes, a target outline and three labelled result callouts. These counts are rendering objects, not unique samples, complete trenches or certified surveyed collars.43 candidate marks were omitted when a matching distinct colour was not recoverable within 3 px. Accepted mark coordinates moved by at most 3 px; see digitisation-audit.json. Trench strokes omit obscured portions, have anonymous display IDs and must not be counted as 14 complete surveyed trenches. Numeric grade-bin edges are not transcribed from the ambiguous low-resolution legend. The original is always available for review.

Source categories remain separate: chemical surface/trench results, radiometric eU, visual mineralogy, collar symbols, interpreted targets, and geophysical profiles. No holes extend below surface in the renderer. Camera, layer and selection operations do not alter geometry. Current title validity, geological continuity, exact sample positions and numerical inversions cannot be established by digitisation.