November 2024

This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 04 November 2024.

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.

OSMM Topography LayerCount on 05/09/2024 (Previous release)Count on 17/10/2024 (Current release)

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

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:

TOIDLocation (i.e. XY coordinates)

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

Discrepancies

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.

Next release

The next release of OS MasterMap Topography Layer is scheduled for 16 December 2024.

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

Geographic areaMinimum area size for land coverMinimum width

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

Geographic areaMinimum area size for land coverMinimum width

Urban

0.1hectares (ha) (1 000m²)

5m

Rural

0.1hectares (ha) (1 000m²)

5m*

Mountain and moorland

0.1hectares (ha) (1 000m²)*

5m*

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.

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 one.

5km tile

OS grid reference

Coordinates (OSGB36)

NS4505

NS 47825 05240

247790.7 605224.0

TOIDs for example one.

OSMM Topography Layer (July 2022)OSMM Topography Layer (August 2022)

osgb1000000316775097

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 two.

5km tile

OS grid reference

Coordinates (OSGB36)

NX3540

NX 37464 41871

237419, 541979

TOIDs for example two.

OSMM Topography Layer (August 2022)

OSMM Topography Layer (October 2022)

osgb1000000318639911

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 three.

5km tile

OS grid reference

Coordinates (OSGB36)

NX6550

NX 68975 51146

268968, 551139

TOIDs for example three.

OSMM Topography Layer (August 2022)

OSMM Topography Layer (October 2022)

osgb1000000319079420

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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