This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 04 November 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 05/09/2024 (Previous release) | Count on 17/10/2024 (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 7 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 16 December 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) |
|---|---|
| Geographic area | Minimum area size for land cover | Minimum width |
|---|---|---|
| Geographic area | Minimum area size for land cover | Minimum width |
|---|---|---|
Total Feature Count
510 067 246
510 670 422
Count of Topo Area
127 597 512
127 758 433
Count of Topo Line
351 522 233
351 963 619
Count of Topo Point
4 390 130
4 391 190
Count of Topo Bline
527 717
524 557
Count of Topo CartoSym
3 785 178
3 780 899
Count of Topo CartoTxt
22 244 476
22 251 724
Total Count of Deletes
562 062
666 186
Count of Topo Area deletions
112 920
138 007
Count of Topo Line deletions
420 657
496 634
Count of Topo Point deletions
2 285
1 941
Count of Topo Bline deletions
3 344
3 858
Count of Topo CartoSym deletions
7 463
7 484
Count of Topo CartoTxt deletions
15 393
18 262
Total Count of Inserts
1 099 911
1 269 362
Count of Topo Area inserts
255 035
298 928
Count of Topo Line inserts
816 716
938 020
Count of Topo Point inserts
3 588
3 001
Count of Topo Bline inserts
444
698
Count of Topo CartoSym inserts
3 699
3 205
Count of Topo CartoTxt inserts
20 429
25 510
Total Count of Modifications
1 095 471
1 257 214
Count of Topo Area Modifications
550 327
643 905
Count of Topo Line Modifications
524 077
597 362
Count of Topo Point Modifications
262
275
Count of Topo Bline Modifications
7 426
2 456
Count of Topo CartoSym Modifications
18
53
Count of Topo CartoTxt Modifications
13 361
13 163
COU Size (bytes)
479 107 436
543 866 589
osgb5000005336454207
236466.509, 628118.225
osgb5000005196539006
329800.731, 477434.786
osgb5000005283135322
507039.113, 375158.152
osgb1000000381134706
128427.853, 919654.391
osgb1000000223021238
333046.984, 476824.072
osgb1000002503313612
518198.08, 452626.12
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*
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
