February 2025
This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 03 February 2025.
OSMM Topography Layer product count
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
511 231 453
511 810 856
Count of Topo Area
127 905 526
128 057 901
Count of Topo Line
352 369 150
352 786 062
Count of Topo Point
4 391 725
4 392 607
Count of Topo Bline
524 140
524 015
Count of Topo CartoSym
3 780 153
3 780 237
Count of Topo CartoTxt
22 260 759
22 270 034
Total Count of Deletes
680 332
765 539
Count of Topo Area deletions
142 472
159 535
Count of Topo Line deletions
516 063
587 397
Count of Topo Point deletions
1 952
2 326
Count of Topo Bline deletions
1 080
552
Count of Topo CartoSym deletions
3 478
3 478
Count of Topo CartoTxt deletions
15 287
13 755
Total Count of Inserts
1 241 363
1 344 942
Count of Topo Area inserts
289 565
311 910
Count of Topo Line inserts
921 594
1 004 309
Count of Topo Point inserts
2 487
2 856
Count of Topo Bline inserts
663
427
Count of Topo CartoSym inserts
2 732
2 410
Count of Topo CartoTxt inserts
24 322
23 030
Total Count of Modifications
1 226 070
1 388 390
Count of Topo Area Modifications
624 491
716 331
Count of Topo Line Modifications
587 411
657 686
Count of Topo Point Modifications
287
260
Count of Topo Bline Modifications
767
671
Count of Topo CartoSym Modifications
22
36
Count of Topo CartoTxt Modifications
13 092
13 406
COU Size (bytes)
530 999 702
589 321 042
Changed TOIDs
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:
osgb1000002052281643
373236.08, 813815.71
osgb5000005228473679
368323.15, 306766.55
osgb5000005164859233
504562.2, 483176.09
osgb1000000168701380
308829.427, 919673.253
osgb5000005213298746
340331.927, 460246.114
osgb5000005333170659
530862.507, 212806.781
Discrepancies
In this release 8 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.
Next release
The next release of OS MasterMap Topography Layer is scheduled for 17 March 2025.
Land cover refinement changes
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:
Old land cover specification
Urban
0.1hectares (ha) (1 000m²)
5m
Rural
0.1hectares (ha) (1 000m²)
10m
Mountain and moorland
1.0hectares (ha) (10 000m²)
10m
New land cover specification
Urban
0.1hectares (ha) (1 000m²)
5m
Rural
0.1hectares (ha) (1 000m²)
5m*
Mountain and moorland
0.1hectares (ha) (1 000m²)*
5m*
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.
Annex A: Rural land cover specification refinement examples
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.
Example one
Location of example area one:
NS4505
NS 47825 05240
247790.7, 605224.0
TOIDs for example area one:
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):
Example two
Location of example area two:
NX3540
NX 37464 41871
237419, 541979
TOIDs for example area two:
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):
Example three
Location of example area three:
NX6550
NX 68975 51146
268968, 551139
TOIDs for example area three:
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):
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