This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 23 September 2024.
The following table contains product counts for this release of OSMM Topography Layer data. The dates shown are extraction dates, not release dates.
| OSMM Topography Layer | Count on 25/07/2024 (Previous release) | Count on 05/09/2024 (Current release) |
|---|---|---|
Numerous TOIDs (Topographic Identifiers) have changed since the last refresh resulting in a visual difference in the data. The list below shows a sample of changed TOIDs and their locations that you can use as 'lookup samples' to validate that your latest supply has updated correctly:
In this release 23 errors were detected, of which, 2 have existed since the previous refresh. These are all considered to be minor errors and there are no major errors present.
We aim to have all errors resolved prior to the next release as part of ongoing quality improvements.
The next release of OS MasterMap Topography Layer is scheduled for 04 November 2024.
The land cover specification for rural geographies has been refined. The Mountain and Moorland refinement was completed in 2022.
The rural geography updates began capture in May 2022. The initial updates fed through to the July 2022 release of OSMM Topography Layer, with the multi class land cover polygons completed in December 2022. The single class land cover polygons will continue to feed through to product from April 2023.
The following two tables articulate this specification refinement:
The asterisk symbol (*) shows which criteria have been refined.
The land cover specification refinement means that the rural land cover data within OSMM Topography Layer will become more granular, producing a more detailed view made up of smaller more numerous polygons. This provides users with more accurate data that meets each individual’s specific requirements. These changes are purely refinements and do not change the data attribution.
Annex A shows three examples of how the rural land cover refinement is being translated into OSMM Topography Layer.
| TOID | Location (i.e. XY coordinates) |
|---|---|
Total Feature Count
509 529 397
510 067 246
Count of Topo Area
127 455 397
127 597 512
Count of Topo Line
351 126 174
351 522 233
Count of Topo Point
4 388 827
4 390 130
Count of Topo Bline
530 617
527 717
Count of Topo CartoSym
3 788 942
3 785 178
Count of Topo CartoTxt
22 239 440
22 244 476
Total Count of Deletes
636 733
562 062
Count of Topo Area deletions
129 723
112 920
Count of Topo Line deletions
478 982
420 657
Count of Topo Point deletions
2 227
2 285
Count of Topo Bline deletions
1 374
3 344
Count of Topo CartoSym deletions
4 265
7 463
Count of Topo CartoTxt deletions
20 162
15 393
Total Count of Inserts
1 283 294
1 099 911
Count of Topo Area inserts
295 954
255 035
Count of Topo Line inserts
949 436
816 716
Count of Topo Point inserts
3 017
3 588
Count of Topo Bline inserts
664
444
Count of Topo CartoSym inserts
3 336
3 699
Count of Topo CartoTxt inserts
30 887
20 429
Total Count of Modifications
1 213 405
1 095 471
Count of Topo Area Modifications
611 739
550 327
Count of Topo Line Modifications
585 817
524 077
Count of Topo Point Modifications
256
262
Count of Topo Bline Modifications
1 485
7 426
Count of Topo CartoSym Modifications
51
18
Count of Topo CartoTxt Modifications
14 057
13 361
COU Size (bytes)
539 082 200
479 107 436
osgb1000000293853171
276700.84, 892218.39
osgb5000005126441008
399800.555, 403814.06
osgb5000005194435102
570821, 186280
osgb1000002574125339
311521.93, 529487.37
osgb5000005216534775
345159.916, 464018.662
osgb5000005307345670
520838.36, 249433.06
Geographic area
Minimum area size for land cover
Minimum width
Urban
0.1hectares (ha) (1 000m²)
5m
Rural
0.1hectares (ha) (1 000m²)
10m
Mountain and moorland
1.0hectares (ha) (10 000m²)
10m
Geographic area
Minimum area size for land cover
Minimum width
Urban
0.1hectares (ha) (1 000m²)
5m
Rural
0.1hectares (ha) (1 000m²)
5m*
Mountain and moorland
0.1hectares (ha) (1 000m²)*
5m*
Below are three real-world examples of how the rural land cover specification refinement has affected the data within OSMM Topography Layer. The examples showcase three areas in southern Scotland where the specification refinement has broken up one land polygon within the Topographic Area Feature Type into smaller, separate polygons.
OSMM Topography Layer (July 2022): osgb1000000316775097
OSMM Topography Layer (August 2022): osgb5000005297485451, osgb5000005297485455, osgb5000005297485456
Source imagery of example area one for comparative purposes:
Data before the rural land cover specification refinement update (OSMM Topography Layer – July 2022):
Data after the rural land cover specification refinement update (OSMM Topography Layer – August 2022):
OSMM Topography Layer (July 2022): osgb1000000318639911
OSMM Topography Layer (August 2022): osgb1000000318639911, osgb5000005298080383, osgb5000005298080465
Source imagery of example area two for comparative purposes:
Data before the rural land cover specification refinement update (OSMM Topography Layer – August 2022):
Data after the rural land cover specification refinement update (OSMM Topography Layer – October 2022):
OSMM Topography Layer (July 2022): osgb1000000319079420
OSMM Topography Layer (August 2022): osgb1000000319079420, osgb5000005298106224
Source imagery of example area three for comparative purposes:
Data before the rural land cover specification refinement update (OSMM Topography Layer – August 2022):
Data after the rural land cover specification refinement update (OSMM Topography Layer – October 2022):
| 5km Tile | OS Grid Reference | Coordinates (OSGB36) |
|---|---|---|
| 5km Tile | OS Grid Reference | Coordinates (OSGB36) |
|---|---|---|
| 5km Tile | OS Grid Reference | Coordinates (OSGB36) |
|---|---|---|
NS4505
NS 47825 05240
247790.7, 605224.0
NX3540
NX 37464 41871
237419, 541979
NX6550
NX 68975 51146
268968, 551139
