August 2024

This release note provides information about the latest release of OS MasterMap (OSMM) Topography Layer, released to customers on 12 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 Layer	Count 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:

TOID	Location (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 23 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 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 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).