April 2024

This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 2nd April 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 01/02/2024 (Previous release)Count on 14/03/2024 (Current release)

Total Feature Count

507 375 850

507 879 548

Count of Topo Area

126 911 673

127 035 158

Count of Topo Line

349 600 457

349 942 731

Count of Topo Point

4 362 057

4 375 415

Count of Topo Bline

532 911

532 572

Count of Topo CartoSym

3 763 697

3 778 000

Count of Topo CartoTxt

22 205 055

22 215 672

Total Count of Deletes

352 971

363 259

Count of Topo Area deletions

72 340

75 296

Count of Topo Line deletions

246 393

253 444

Count of Topo Point deletions

4 698

4 059

Count of Topo Bline deletions

433

561

Count of Topo CartoSymcc deletions

11 208

8 953

Count of Topo CartoTxtcc deletions

17 899

20 946

Total Count of Inserts

811 142

866 957

Count of Topo Area inserts

180 007

198 781

Count of Topo Line inserts

551 663

595 718

Count of Topo Point inserts

21 692

17 417

Count of Topo Bline inserts

353

222

Count of Topo CartoSym inserts

29 505

23 256

Count of Topo CartoTxt inserts

27 922

31 563

Total Count of Modifications

600 677

634 202

Count of Topo Area Modifications

294 892

309 690

Count of Topo Line Modifications

291 597

308 659

Count of Topo Point Modifications

326

311

Count of Topo Bline Modifications

628

1 403

Count of Topo CartoSym Modifications

132

40

Count of Topo CartoTxt Modifications

13 102

14 099

COU Size (bytes)

386 470 897

336 114 289

Discrepancies

9 minor errors were detected, which is 2 more than were found in the last refresh. Of these 9 errors, 2 have existed since the previous refresh. All errors are considered to be minor errors. We aim to have all errors resolved prior to the next release as part of ongoing quality improvement.

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.

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:

TOID

Location (i.e. XY coordinates)

osgb5000005109728428

322926.508, 704955.071

oosgb5000005252408974

396225, 4754643

osgb1000000030598131

504443.618, 242017.376

osgb1000000293839535

203531.7, 862031.28

osgb5000005299999425

406660.07, 436264.33

osgb5000005243520249

505688.732, 484331.45

Next release

The next release of OS MasterMap Topography Layer is scheduled for 13th May 2024.

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):

Last updated