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Units of NTv2 accuracy samples ?
Even Rouault edited this page Dec 8, 2019
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13 revisions
| NTv2 filename | Producer | Min/Mean/Max lat accuracy | Unit | Confirmed by producer |
|---|---|---|---|---|
| rdtrans2008/rdtrans2018.gsb | Kadaster | 1e-3 / 1e-3 / 1e-3 | Metre | Yes |
| ntv2_0.gsb | NRCan | 0 / 0.27 / 13 (1st subgrid) | Metre | Yes |
| ntf_r93.gsb | IGN France | 1.6e-4 / 0.035 / 0.065 | Second | Yes |
| BWTA2017.gsb | LGL | 1.6e-5 / 6.3e-5 / 1.4e-4 | Second ? | Not yet... |
| nzgd2kgrid0005.gsb | LINZ | 5.9e-4 / 0.03 / 0.1 | Second ? | Not yet... |
| OSTN15_NTv2_OSGBtoETRS.gsb | Ordnance Survey | 1e-6 / 5e-6 / 3e-5 | Second ? | Not yet... |
| bd72lb72_etrs89lb08.gsb | IGN Belgium | 0.01 / 0.01 / 0.01 | Metre ? | Not yet... |
| CHENyx06a.gsb | Swisstopo | 1e-3 / 1e-3 / 1e-3 | ???? | Not yet... |
| D73_ETRS89_geo.gsb | DGTerritorio | 1.5e-3 / 1.5e-3 / 1.5e-3 | Second ? | Not yet... |
| GDA94_GDA2020_conformal_and | ICSM | 1e-7 / 7e-4 / 3e-2 (1st subgrid) | Second ? | Not yet... |
| _distortion.gsb | Use nodata = -1 | |||
| A66_National_13_09_01.gsb | ICSM | 1e-3 / 8e-3 / 1e-2 (1st subgrid) | Second ? | Not yet... |
Remarks:
- bd72lb72_etrs89lb08.gsb : documented by EPSG to have a 0.01 m accuracy
- CHENyx06a.gsb: EPSG documents a 0.20 m accuracy. 1e-3 arc-second corresponds to 0.03 m. Hard to decide...
- D73_ETRS89_geo.gsb: the lat accuracy is 1.5e-3 and the lon accuracy is 1.9e-3. If using a latitude = 36 degree, 1.9e-3 * cos(36 degree) ~= 1.5 e-3. Hence a hint the unit might be seconds