February 2024

This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 19 February 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 14/12/2023 (Previous Release)	Count on 01/02/2024 (Current Release)
Total Feature Count	506 917 679	507 375 850
Count of Topo Area	126 804 006	126 911 673
Count of Topo Line	349 295 187	349 600 457
Count of Topo Point	4 345 063	4 362 057
Count of Topo Bline	532 991	532 911
Count of Topo CartoSym	3 745 400	3 763 697
Count of Topo CartoTxt	22 195 032	22 205 055
Total Count of Deletes	333 884	352 971
Count of Topo Area deletions	70 410	72 340
Count of Topo Line deletions	231 489	246 393
Count of Topo Point deletions	3 420	4 698
Count of Topo Bline deletions	828	433
Count of Topo CartoSymcc deletions	7 670	11 208
Count of Topo CartoTxtcc deletions	20 067	17 899
Total Count of Inserts	767 416	811 142
Count of Topo Area inserts	176 713	180 007
Count of Topo Line inserts	526 812	551 663
Count of Topo Point inserts	15 012	21 692
Count of Topo Bline inserts	391	353
Count of Topo CartoSym inserts	18 520	29 505
Count of Topo CartoTxt inserts	29 968	27 922
Total Count of Modifications	515 536	600 677
Count of Topo Area Modifications	246 717	294 892
Count of Topo Line Modifications	254 055	291 597
Count of Topo Point Modifications	254	326
Count of Topo Bline Modifications	955	628
Count of Topo CartoSym Modifications	45	132
Count of Topo CartoTxt Modifications	13 510	13 102
COU Size (bytes)	347 863 984	386 470 897

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 7 minor errors were detected, which is 1 more than the 6 errors found in the last refresh. Of these errors, 1 has existed since the previous refresh. 6 of these are minor issues – these are minor issues with no visible issues, and there is 1 serious error of a double digitised line.

We aim to have all errors resolved prior to the next release as part of ongoing quality improvements.

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)
osgb1000000175416836	332000, 721912.22
osgb1000000230216079	335945.87, 440115.421
osgb5000005128685631	578813.895, 172187.251
osgb5000005327816366	265014.445, 842929.902
osgb5000005328747598	400486.093, 278819.54
osgb5000005154766496	617199.12, 165232.91

Next release

The next release of OS MasterMap Topography Layer is scheduled for 02 April 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).