June 2024

This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 24th June 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 25/04/2024 (Previous release)Count on 06/06/2024 (Current release)

Total Feature Count

508 329 170

508 882 836

Count of Topo Area

127 146 339

127 289 166

Count of Topo Line

350 253 247

350 655 720

Count of Topo Point

4 385 721

4 388 037

Count of Topo Bline

532 257

531 327

Count of Topo CartoSym

3 788 842

3 789 871

Count of Topo CartoTxt

22 222 764

22 228 715

Total Count of Deletes

387 625

602 375

Count of Topo Area deletions

78 038

119 554

Count of Topo Line deletions

277 326

449 655

Count of Topo Point deletions

3 039

2 553

Count of Topo Bline deletions

533

1 350

Count of Topo CartoSymcc deletions

6 393

4 460

Count of Topo CartoTxtcc deletions

22 296

24 803

Total Count of Inserts

837 247

1 156 041

Count of Topo Area inserts

189 219

262 381

Count of Topo Line inserts

587 842

852 128

Count of Topo Point inserts

13 345

4 869

Count of Topo Bline inserts

218

420

Count of Topo CartoSym inserts

17 235

5 489

Count of Topo CartoTxt inserts

29 388

30 754

Total Count of Modifications

736 646

1 181 874

Count of Topo Area Modifications

369 267

601 058

Count of Topo Line Modifications

353 690

563 973

Count of Topo Point Modifications

231

220

Count of Topo Bline Modifications

2 681

2 947

Count of Topo CartoSym Modifications

44

46

Count of Topo CartoTxt Modifications

10 733

13 630

COU Size (bytes)

333 062 363

507 742 477

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)

osgb1000000828071143

283459.15, 558287.03

osgb1000032166978

420041.3, 420633.65

osgb1000002023902176

570547.2, 321617.6

osgb1000000051338601

400106.45, 867491.455

osgb5000005222007891

334818.55, 415223.62

osgb1000001792732699

516068.135, 172721.936

Discrepancies

In this release 5 minor errors were detected, of which 2 have existed since the previous refresh. All errors detected are considered to be minor. We aim to have all 5 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 12 August 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 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

New land cover specification

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*

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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