January 2024

This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 04 January 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 Layer	Count on 02/11/2023 (Previous Release)	Count on 14/12/2023 (Current Release)
Total Feature Count	506 484 147	506 917 679
Count of Topo Area	126 697 703	126 804 006
Count of Topo Line	348 999 864	349 295 187
Count of Topo Point	4 333 471	4 345 063
Count of Topo Bline	533 428	532 991
Count of Topo CartoSym	3 734 550	3 745 400
Count of Topo CartoTxt	22 185 131	22 195 032
Total Count of Deletes	482 784	333 884
Count of Topo Area deletions	78 620	70 410
Count of Topo Line deletions	360 998	231 489
Count of Topo Point deletions	3 993	3 420
Count of Topo Bline deletions	591	828
Count of Topo CartoSymcc deletions	9 635	7 670
Count of Topo CartoTxtcc deletions	28 947	20 067
Total Count of Inserts	915 049	767 416
Count of Topo Area inserts	214 888	176 713
Count of Topo Line inserts	624 246	526 812
Count of Topo Point inserts	16 055	15 012
Count of Topo Bline inserts	398	391
Count of Topo CartoSym inserts	21 829	18 520
Count of Topo CartoTxt inserts	37 633	29 968
Total Count of Modifications	681 711	515 536
Count of Topo Area Modifications	289 725	246 717
Count of Topo Line Modifications	369 012	254 055
Count of Topo Point Modifications	374	254
Count of Topo Bline Modifications	674	955
Count of Topo CartoSym Modifications	57	45
Count of Topo CartoTxt Modifications	21 869	13 510
COU Size (bytes)	402 922 509	347 863 984

New formats available

Alongside GML format, OSMM Topography Layer is also available in GeoPackage and vector tiles formats (from March 2023). Please see the Getting Started with GeoPackage and Getting Started with Vector Tiles guides for more information on using these new formats. The product is supplied as an online download. You can download data in its various formats from the OS Data Hub.

Discrepancies

In this release 6 minor errors were detected, which is 20 less than the 26 errors found in the last refresh. Of these errors, 2 have existed since the previous refresh – these are minor issues caused by conflict (where the geometry of adjacent feature has not been updated to match), but there are no visible issues.

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.

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)
osgb1000000168404255	328579.99, 958515.98
osgb5000005152517605	348374.945, 431019.423
osgb1000001824692637	541419.437, 101834.574
osgb1000000385134315	188967, 835637.5
osgb5000005299962750	416833.55, 444757.47
osgb1000000013827617	508743.536, 482017.503

Next release

The next release of OS MasterMap Topography Layer is scheduled for 19 February 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 area one:

5km Tile	OS Grid Reference	Coordinates (OSGB36)
NS4505	NS 47825 05240	247790.7, 605224.0

TOIDs for example area one:

• OSMM Topography Layer (July 2022): osgb1000000316775097

• OSMM Topography Layer (August 2022): osgb5000005297485451, osgb5000005297485455, osgb5000005297485456

Source imagery of example area one for comparative purposes:

Photo of imagery of an area in southern Scotland taken in January 2021 highlighting an area of rural land cover. Provided for comparative purposes to show how the rural land cover specification refinement has altered the data in example area 1.

Data before the rural land cover specification refinement update (OSMM Topography Layer – July 2022):

Screenshot of what the data in example area 1 looked like prior to the rural land cover specification refinement update (July 2022 OS MasterMap Topography Layer data).

Data after the rural land cover specification refinement update (OSMM Topography Layer – August 2022):

Screenshot of what the data in example area 1 looked like after the rural land cover specification refinement update (August 2022 OS MasterMap Topography Layer data).

Example two

Location of example area two:

5km Tile	OS Grid Reference	Coordinates (OSGB36)
NX3540	NX 37464 41871	237419, 541979

TOIDs for example area two:

• OSMM Topography Layer (July 2022): osgb1000000318639911

• OSMM Topography Layer (August 2022): osgb1000000318639911, osgb5000005298080383, osgb5000005298080465

Source imagery of example area two for comparative purposes:

Photo of imagery of an area in southern Scotland highlighting an area of rural land cover. Provided for comparative purposes to show how the rural land cover specification refinement has altered the data in example area 2.

Data before the rural land cover specification refinement update (OSMM Topography Layer – August 2022):

Screenshot of what the data in example area 2 looked like prior to the rural land cover specification refinement update (August 2022 OS MasterMap Topography Layer data).

Data after the rural land cover specification refinement update (OSMM Topography Layer – October 2022):

Screenshot of what the data in example area 2 looked like after the rural land cover specification refinement update (October 2022 OS MasterMap Topography Layer data).

Example three

Location of example area three:

5km Tile	OS Grid Reference	Coordinates (OSGB36)
NX6550	NX 68975 51146	268968, 551139

TOIDs for example area three:

• OSMM Topography Layer (July 2022): osgb1000000319079420

• OSMM Topography Layer (August 2022): osgb1000000319079420, osgb5000005298106224

Source imagery of example area three for comparative purposes:

Photo of imagery of an area in southern Scotland highlighting an area of rural land cover. Provided for comparative purposes to show how the rural land cover specification refinement has altered the data in example area 3.

Data before the rural land cover specification refinement update (OSMM Topography Layer – August 2022):

Screenshot of what the data in example area 3 looked like prior to the rural land cover specification refinement update (August 2022 OS MasterMap Topography Layer data).

Data after the rural land cover specification refinement update (OSMM Topography Layer – October 2022):

Screenshot of what the data in example area 3 looked like after the rural land cover specification refinement update (October 2022 OS MasterMap Topography Layer data).