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The following table contains product counts for this release of OSMM Topography Layer data. The dates shown are extraction dates, not release dates.
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 33 errors were detected, of which, 3 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 28 April 2025.
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.
Total Feature Count
511 810 856
512 632 961
Count of Topo Area
128 057 901
128 273 981
Count of Topo Line
352 786 062
353 377 395
Count of Topo Point
4 392 607
4 394 656
Count of Topo Bline
524 015
523 727
Count of Topo CartoSym
3 780 237
3 780 848
Count of Topo CartoTxt
22 270 034
22 282 354
Total Count of Deletes
765 539
814 144
Count of Topo Area deletions
159 535
175 473
Count of Topo Line deletions
587 397
616 657
Count of Topo Point deletions
1 974
2 235
Count of Topo Bline deletions
552
707
Count of Topo CartoSym deletions
2 326
3 024
Count of Topo CartoTxt deletions
13 755
16 048
Total Count of Inserts
1 344 942
1 636 249
Count of Topo Area inserts
311 910
391 553
Count of Topo Line inserts
1 004 309
1 207 990
Count of Topo Point inserts
2 856
4 284
Count of Topo Bline inserts
427
419
Count of Topo CartoSym inserts
2 410
3 635
Count of Topo CartoTxt inserts
23 030
28 368
Total Count of Modifications
1 388 390
1 640 594
Count of Topo Area Modifications
716 331
826 746
Count of Topo Line Modifications
657 686
782 736
Count of Topo Point Modifications
260
262
Count of Topo Bline Modifications
671
1 304
Count of Topo CartoSym Modifications
36
21
Count of Topo CartoTxt Modifications
13 406
29 525
COU Size (bytes)
589 321 042
675 322 893
osgb5000005299253195
412771.500, 601311.887
osgb5000005263740431
422076.291, 299541.750
osgb1000000013979343
510060.446, 476948.989
osgb1000000292571752
273370.555, 873670.418
osgb5000005284097242
372550.824, 407494.624
osgb1000002006355269
5523489.470, 432425.260
Urban
0.1hectares (ha) (1 000m²)
5m
Rural
0.1hectares (ha) (1 000m²)
10m
Mountain and moorland
1.0hectares (ha) (10 000m²)
10m
Urban
0.1hectares (ha) (1 000m²)
5m
Rural
0.1hectares (ha) (1 000m²)
5m*
Mountain and moorland
0.1hectares (ha) (1 000m²)*
5m*
This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 17 March 2025.
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.
NS4505
NS 47825 05240
247790.7, 605224.0
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):
NX3540
NX 37464 41871
237419, 541979
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):
NX6550
NX 68975 51146
268968, 551139
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):
