This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 16 December 2024.
The following table contains product counts for this release of OSMM Topography Layer data. The dates shown are extraction dates, not release dates.
Total Feature Count
510 670 422
511 231 453
Count of Topo Area
127 758 433
127 905 526
Count of Topo Line
351 963 619
352 369 150
Count of Topo Point
4 391 190
4 391 725
Count of Topo Bline
524 557
524 140
Count of Topo CartoSym
3 780 899
3 780 153
Count of Topo CartoTxt
22 251 724
22 260 759
Total Count of Deletes
666 186
680 332
Count of Topo Area deletions
138 007
142 472
Count of Topo Line deletions
496 634
516 063
Count of Topo Point deletions
1 941
1 952
Count of Topo Bline deletions
3 858
1 080
Count of Topo CartoSym deletions
7 484
3 478
Count of Topo CartoTxt deletions
18 262
15 287
Total Count of Inserts
1 269 362
1 241 363
Count of Topo Area inserts
298 928
289 565
Count of Topo Line inserts
938 020
921 594
Count of Topo Point inserts
3 001
2 487
Count of Topo Bline inserts
698
663
Count of Topo CartoSym inserts
3 205
2 732
Count of Topo CartoTxt inserts
25 510
24 322
Total Count of Modifications
1 257 214
1 226 070
Count of Topo Area Modifications
643 905
624 491
Count of Topo Line Modifications
597 362
587 411
Count of Topo Point Modifications
275
287
Count of Topo Bline Modifications
2 456
767
Count of Topo CartoSym Modifications
53
22
Count of Topo CartoTxt Modifications
13 163
13 092
COU Size (bytes)
543 866 589
530 999 702
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:
osgb5000005336348561
303087.887, 857162.222
osgb5000005331742080
360972.262, 394804.694
osgb1000001644059895
515401.35, 461688.52
osgb1000000288040716
216861.731, 933944.811
osgb1000000223011430
331477.816, 481794.328
osgb5000005256265197
559369.893, 313898.605
In this release 5 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 03 February 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:
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*
Note: 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.
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):
