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Merge pull request #132 from rouault/fr_ign_RGM04versRGM23
Add grid fr_ign_RGM04versRGM23.tif for RGM04 -> RGM23 datum shift (Mayotte)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| #!/usr/bin/env python | ||
| ############################################################################### | ||
| # Project: PROJ | ||
| # Purpose: Convert IGN France geocentric RGM04versRGM23.txt grid | ||
| # Author: Even Rouault <even.rouault at spatialys.com> | ||
| # | ||
| ############################################################################### | ||
| # Copyright (c) 2025, Even Rouault <even.rouault at spatialys.com> | ||
| # | ||
| # SPDX-License-Identifier: MIT | ||
| ############################################################################### | ||
|
|
||
| from osgeo import gdal | ||
| from osgeo import osr | ||
| import datetime | ||
| import struct | ||
|
|
||
| # https://geodesie.ign.fr/contenu/fichiers/documentation/RGM04versRGM23.txt | ||
|
|
||
| with open('RGM04versRGM23.txt', 'rt') as f: | ||
| count_val_rows = 0 | ||
| for line_no, l in enumerate(f.readlines()): | ||
| if l[-1] == '\n': | ||
| l = l[0:-1] | ||
| if l[-1] == '\r': | ||
| l = l[0:-1] | ||
| if line_no == 0: | ||
| assert l.startswith(' GR3D ') | ||
| elif line_no == 1: | ||
| assert l.startswith(' GR3D1 ') | ||
| tokens = [] | ||
| for t in l.split(' '): | ||
| if t: | ||
| tokens.append(t) | ||
| assert len(tokens) == 7 | ||
| minx = float(tokens[1]) | ||
| maxx = float(tokens[2]) | ||
| miny = float(tokens[3]) | ||
| maxy = float(tokens[4]) | ||
| resx = float(tokens[5]) | ||
| resy = float(tokens[6]) | ||
| assert minx < maxx | ||
| assert miny < maxy | ||
| assert resx > 0 | ||
| assert resy > 0 | ||
| cols = 1 + (maxx - minx) / resx | ||
| assert cols - int(cols + 0.5) < 1e-10 | ||
| cols = int(cols + 0.5) | ||
| rows = 1 + (maxy - miny) / resy | ||
| assert rows - int(rows + 0.5) < 1e-10 | ||
| rows = int(rows + 0.5) | ||
| ds = gdal.GetDriverByName('GTiff').Create( | ||
| '/vsimem/gr3df97a.tif', cols, rows, 3, gdal.GDT_Float32) | ||
| ds.SetMetadataItem( | ||
| 'TIFFTAG_COPYRIGHT', 'Derived from work by IGN France. Open License https://www.etalab.gouv.fr/wp-content/uploads/2014/05/Open_Licence.pdf') | ||
| ds.SetMetadataItem('TIFFTAG_IMAGEDESCRIPTION', | ||
| 'Geocentric translation from RGM04 (EPSG:4468) to RGM23 (EPSG:10669). Converted from RGM04versRGM23.txt') | ||
| datetime = datetime.date.today().strftime("%Y:%m:%d %H:%M:%S") | ||
| ds.SetMetadataItem('TIFFTAG_DATETIME', datetime) | ||
| ds.SetMetadataItem('AREA_OR_POINT', 'Point') | ||
| ds.SetMetadataItem('TYPE', 'GEOCENTRIC_TRANSLATION') | ||
| ds.SetMetadataItem('area_of_use', 'Mayotte') | ||
| ds.SetMetadataItem('source_crs_epsg_code', '4468') | ||
| ds.SetMetadataItem('target_crs_epsg_code', '10669') | ||
| ds.SetGeoTransform( | ||
| [minx - resx/2, resx, 0, maxy + resy/2, 0, -resy]) | ||
| ds.GetRasterBand(1).SetUnitType('metre') | ||
| ds.GetRasterBand(1).SetDescription('x_translation') | ||
| ds.GetRasterBand(2).SetUnitType('metre') | ||
| ds.GetRasterBand(2).SetDescription('y_translation') | ||
| ds.GetRasterBand(3).SetUnitType('metre') | ||
| ds.GetRasterBand(3).SetDescription('z_translation') | ||
| sr = osr.SpatialReference() | ||
| sr.ImportFromEPSG(10671) # RGM23 | ||
| ds.SetProjection(sr.ExportToWkt()) | ||
| elif line_no == 2: | ||
| assert l.startswith(' GR3D2 ') | ||
| elif line_no == 3: | ||
| assert l.startswith(' GR3D3 ') | ||
| else: | ||
| tokens = [] | ||
| for t in l.split(' '): | ||
| if t: | ||
| tokens.append(t) | ||
| assert len(tokens) == 6 | ||
| lon = float(tokens[0]) | ||
| lat = float(tokens[1]) | ||
| dx = float(tokens[2]) | ||
| dy = float(tokens[3]) | ||
| dz = float(tokens[4]) | ||
| iy = (line_no - 4) % rows | ||
| ix = (line_no - 4) // rows | ||
| assert abs(lon - (minx + ix * resx) | ||
| ) < 1e-10, (line_no, lon, minx + ix * resx) | ||
| assert abs(lat - (miny + iy * resy) | ||
| ) < 1e-10, (line_no, lat, miny + iy * resy) | ||
| ds.GetRasterBand(1).WriteRaster( | ||
| ix, rows - iy - 1, 1, 1, struct.pack('f', dx)) | ||
| ds.GetRasterBand(2).WriteRaster( | ||
| ix, rows - iy - 1, 1, 1, struct.pack('f', dy)) | ||
| ds.GetRasterBand(3).WriteRaster( | ||
| ix, rows - iy - 1, 1, 1, struct.pack('f', dz)) | ||
| count_val_rows += 1 | ||
|
|
||
| assert count_val_rows == rows * cols | ||
| gdal.GetDriverByName('GTiff').CreateCopy('fr_ign_RGM04versRGM23.tif', ds, options=[ | ||
| 'COMPRESS=DEFLATE', 'PREDICTOR=3', 'INTERLEAVE=BAND']) |
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