August 2024

This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 12th August 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 06/06/2024 (Previous release)Count on 25/07/2024 (Current release)

Total Feature Count

508 882 836

509 529 397

Count of Topo Area

127 289 166

127 455 397

Count of Topo Line

350 655 720

351 126 174

Count of Topo Point

4 388 037

4 388 827

Count of Topo Bline

531 327

530 617

Count of Topo CartoSym

3 789 871

3 788 942

Count of Topo CartoTxt

22 228 715

22 239 440

Total Count of Deletes

602 375

636 733

Count of Topo Area deletions

119 554

129 723

Count of Topo Line deletions

449 655

478 982

Count of Topo Point deletions

2 553

2 227

Count of Topo Bline deletions

1 350

1 374

Count of Topo CartoSymcc deletions

4 460

4 265

Count of Topo CartoTxtcc deletions

24 803

20 162

Total Count of Inserts

1 156 041

1 283 294

Count of Topo Area inserts

262 381

295 954

Count of Topo Line inserts

852 128

949 436

Count of Topo Point inserts

4 869

3 017

Count of Topo Bline inserts

420

664

Count of Topo CartoSym inserts

5 489

3 336

Count of Topo CartoTxt inserts

30 754

30 887

Total Count of Modifications

1 181 874

1 213 405

Count of Topo Area Modifications

601 058

611 739

Count of Topo Line Modifications

563 973

585 817

Count of Topo Point Modifications

220

256

Count of Topo Bline Modifications

2 947

1 485

Count of Topo CartoSym Modifications

46

51

Count of Topo CartoTxt Modifications

13 630

14 057

COU Size (bytes)

507 742 477

539 082 200

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)

osgb5000005333761759

266379.141, 661146.076

osgb1000002102169148

330922.334, 436520.256

osgb1000001792521555

514257.13, 177195.224

osgb1000000390862765

181610.432, 697265.48

osgb1000002031686162

377705.95, 414622.45

osgb5000005127065768

563861.53, 189432.44

Discrepancies

In this release 23 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 23rd September 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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