Styled Layer Descriptor (SLD) stylesheets are used by a number of desktop applications and geographic servers for styling both vector and raster data. SLDs are an OGC standard.

Note: The SLDs released by OS were written and tested in GeoServer; you may need to adapt them to work with your software.

The following steps guide you through the process of loading the SLDs in GeoServer and associating them with OS MasterMap Topography Layer.

The instructions assume that you have already setup a workspace and store, and added the OS MasterMap Topography Layer data.

To use the SLD stylesheets:

1. Login to the GeoServer admin panel.
2. Click Open Layers in the Data menu in the left panel to view the OSMM topography layers: “boundaryline”, “cartographicsymbol”, “cartographictext”, “topographicarea”, “topgraphicline” and “topographicpoint”.
3. To upload the new SLD style files:

   • Click Styles in the Data menu in the left panel.

• Click Add a new style.

• Click Choose File in the Style file field at the bottom of the page, select one of the SLD files on your computer, and click Upload.

• The page will refresh to display the uploaded SLD file.

• Click Submit.

• Repeat this procedure (steps b. to e. above) for the other SLD files.

1. To associate the uploaded SLD files with their respective data layers:

   • Click Layers in the Data menu in the left panel.

• Click a layer (for example, “topographicarea”) to open the Edit Layer view.

• Select the Publishing tab, scroll to the Default Style field, and select the SLD (uploaded in the previous step) that matches the selected data layer in drop-down menu.

• Repeat this procedure (steps a. to c. above) for the other layers.

1. Once all the SLDs have been associated with layers you can view the data.

• The SLDs have a minimum viewing scale of 1:4000.

• We recommend adding a background colour layer of RGB (228, 244, 247).

The following steps guide you through the process of loading the LYR (Esri Layer) stylesheets in ArcMap and associating them with OS MasterMap Topography Layer.

To use the LYR (Esri Layer) stylesheets:

1. Install the OSMasterMap font on your computer:

This gives you the OS MasterMap symbology.

• Navigate to the “OSMM-Topography-Layer-stylesheets/Schema version 9/Stylesheets/ESRI stylesheets (LYR)” folder and double-click “OSMasterMap.ttf”.

• Click Install in the OSMasterMap (True Type) dialog.

• You may need Administrator privileges to install a new font.

1. In ArcMap, open a new blank map.

2. Use the Catalog to navigate to “OSMM-Topography-Layer-v9.lyr” and load it into your project.

The red exclamation marks next to the layer names means you need to repair the data source.

1. Connect the LYR stylesheets to the OS MasterMap Topography Layer data layers:

   • Double-click a layer, for example “TopographicArea”.

   • In the Layer Properties dialog, select the Source tab and click Set Data Source.

   • In the Data Source dialog, navigate to the database containing OS MasterMap Topography Layer, select the matching layer, and click Add.
   • Repeat this procedure (the three steps above) for the other data layers.

• We recommend setting a reference scale of 1:2000 and viewing the map between 1:500 and 1:4000 for maximum legibility. The minimum viewing scale is set at 1:4000.

• We also recommend adding a background colour layer of RGB (228, 244, 247).

• Your map should now look similar to this:

The following steps guide you through the process of loading the LYRX stylesheets into ArcGIS Pro and associating them with OS MasterMap Topography Layer.

To use the LYRX stylesheets:

1. Install the OSMasterMap font on your computer: This gives you the OS MasterMap symbology.

   • Navigate to the “OSMM-Topography-Layer-stylesheets/Schema version 9/Stylesheets/ArcGIS Pro stylesheets (LYRX)” folder and double-click “OSMasterMap.ttf”.

   • Click Install in the OSMasterMap (True Type) dialog.

You may need Administrator privileges to install a new font.

1. In ArcGIS Pro, open a new blank map.

2. Use the Catalog to navigate to “OSMM Topography Layer (Preferred style).lyrx” and load it into your project.

The red exclamation marks next to the layer names means you need to repair the data source.

• To fix the broken data links, connect the LYRX stylesheets to the OS MasterMap Topography Layer data layers:

  • Double-click a layer, for example “TopographicArea”.

  • In the Change data source dialog, navigate to the database containing OS MasterMap Topography Layer, select the matching layer, and click Add.
• Repeat this procedure (steps a. and b. above) for the other data layers.

• We recommend setting a reference scale of 1:2000 and viewing the map between 1:500 and 1:4000 for maximum legibility. The minimum viewing scale is set at 1:4000.

• We also recommend adding a background colour layer of RGB (228, 244, 247).

• Your map should now look similar to this:

The following steps guide you through the process of loading the QML stylesheets in QGIS and associating them with OS MasterMap Topography Layer.

To use QML (QGIS) stylesheets:

1. Navigate to the “OSMM-Topography-Layer-stylesheets/Schema version 9/Stylesheets/QGIS stylesheets (OML)” folder and double-click “OSMasterMap.ttf”.

2. Click Install in the OSMasterMap (True Type) dialog.

You may need Administrator privileges to install a new font.

1. Copy the “osmmsymbols” folder into the QGIS “svg” folder on your computer.

The “osmmsymbols” folder is in “OSMM-Topography-Layer-stylesheets/Schema version 9/Stylesheets/QGIS stylesheets (QML)” folder of the extracted GitHub files.

The “svg” folder is typically in “C:\<program folder>\QGIS <version>\apps\qgis-ltr\svg”, for example, “C:\Program Files\QGIS 3.22.4\apps\qgis-ltr\svg”.

You may need to re-open QGIS if you had it open during this step.

1. Load in the OS MasterMap Topography Layer data from your database.

2. To load the stylesheets:

   • Double-click a layer to open the Layer Properties dialog:

   • In the Layer Rendering section (bottom left), click Style > Load Style.

   • In the Database Styles Manager dialog, click “…” next to the File field, select the QML file (.qml) that matches the selected layer, and then click Load Style.

The QML files are in the “/OSMM-Topography-Layer-stylesheets-master/Schema version 9/Stylesheets/QGIS stylesheets (QML)” folder of the extracted GitHub files.

Click OK to close the Layer Properties dialog.

1. Repeat this procedure (steps a. to d. above) for the other OS MasterMap Topography Layer layers

For the best visibility, we recommend you order the layers as follows: “cartographictext”, “cartographicsymbol”, “topographicpoint”, “boundaryline”, “topographicline”, “topographicarea”. You can use drag and drop to reorder the layers.

• We recommend viewing the map at a scale of between 1:500 and 1:4000. For maximum legibility we have set the minimum viewing scale at 1:4000.

• We recommend adding a background colour of R:228,G:244,B:247

• Your map should now look similar to this:

This section is only relevant if you are using GML data. The data in the GeoPackage and Vector tiles (MBTiles) formats of the product already include a style_code column and other

As mentioned in the previous section, the structure of your database and data depends on how you load your data. You need to use the SQL query that correctly matches your data structure. Different operators are available to find the attribute values, depending on whether your data is loaded as a string or an array.

For example, in PostGIS:

• String: You can use the ~operator to find a value within the string of values, for example: WHEN descriptivegroup ~ ‘Building’ AND descriptiveterm IS NULL THEN ‘Building Fill’

• Array: You can use the @> (contains) operator to find a value within the array of values, for example: WHEN descriptivegroup @> ‘{Building}’ AND descriptiveterm IS NULL THEN ‘Building Fill’

Both types of SQL query create a new table using a CASE statement. This is more efficient than using an UPDATE SET statement, because the PostgreSQL MVCC model creates a new row for each row affected by the UPDATE. This means that the original rows then need to be deleted. Previous tests that compared the methods showed that the CASE method took seven hours for a GB OS MasterMap Topography Layer set, whereas the UPDATE method took several days.

Because the queries essentially create duplicate tables, you need to ensure that you have enough server hard drive space before running them.

The example below uses pgAdmin III.

To run either SQL query:

1. Open pgAdmin.

1. Click (Execute SQL Query) in the toolbar.

2. Copy the SQL code from the correct PostGIS SQL file and paste into the PostGIS SQL Query window.

See scripts above for guidance on how to choose the correct script.

1. Click (Execute Query) in the toolbar to run the script.

At Ordnance Survey we run all the SQL scripts (that is, for all feature types) simultaneously. Before attempting this, please check that your PostgreSQL configuration is set to handle this approach because it may consume a lot of server resources.

Post processing may take several hours, depending on the amount of OS MasterMap Topography Layer data you have loaded and your configuration settings.

1. After the SQL query has run, you will have both your original database table (for example “osmm. topo.topographicarea”) and a new table that includes the additional styling attributes (for example, “osmm_topo.topographicarea_styled”). You can manage these tables in one of two ways:

   • DROP/DELETE the original table and rename the new styled table the name of the original table. The advantage of this is that existing connections to that database table will continue to work.

   • DROP/DELETE the original table and leave the new styled table as it is. The disadvantage of this is that an existing database connection looking for your original table will fail; you will need to connect to the new styled database table.

The SQL scripts for Oracle work with descriptiveGroup and descriptiveTerm attributes that are strings and use the INSTR function to find attribute values within the string. We chose to use INSTR rather than LIKE because in our tests INSTR SQL queries ran faster. The Oracle scripts UPDATE and SET the new style_description and style_code attributes and you need to add extra columns to your database tables for these attributes before running the SQL scripts.

The example below adds the style_description attribute to the “topographicarea” table. We use SQL Developer to run the SQL script.

To run the Oracle SQL queries:

1. Open SQL Developer and navigate to the database in which your OS MasterMap Topography Layer is stored.

2. Add the extra attribute column/s:

Our example adds a “style_description” column to the “sw_topographicarea” table.

• In the Connections panel select the table to which you want to add a new attribute column/s. In the Worksheet area, enter an SQL query to add the a new attribute column.

Substitute the table name as necessary.

• Click (Run) to run the query.

If the SQL runs successfully, the message “table <table name> altered” for example “table SW_TOPOGRAPHICAREA altered” will display in the Script Output area (below the Worksheet area).

• Click in the Connections panel to refresh the list. This ensures that the new “style_description/style_code” column displays in the list.

• In the Connections panel, select the table (for example, “sw_topographicarea”) once again. A new tab showing the revised data structure of the table (including the new column) will open.

• Repeat this procedure (steps a. to d. above) for the other OS MasterMap Topography Layer database tables.

CartographicText requires additional attributes to be added before running the SQL below:

1. Run the styling SQL scripts using the same procedure as above:

   • Select the appropriate table in the Connections panel (for example, “sw_topographicarea”).

   • Copy and paste the content of the matching SQL script (for example, “topographicarea_update_string.sql”) into the Worksheet area.

   • Click (Run) to run the query.

   • Repeat this procedure (steps a. to c. above) for the other OS MasterMap Topography Layer database tables.

You can now go ahead and use the new stylesheets with the data.

The SQL scripts for SQL Server work with descriptiveGroup and descriptiveTerm attributes that are strings and use the CHARINDEX function to find attribute values within the string. The SQL Server scripts UPDATE and SET the new style_description and style_code attributes. Before running the SQL scripts, you need to add extra columns for these attributes to your database tables.

To run the SQL Server scripts:

1. Open SQL Server Management Studio and connect to your OS MasterMap Topography Layer database.

2. Add new attribute column/s:

   • Open the Query Editor and run the following SQL query.

Our example query adds “style_description” and “style_code” columns to a database table called “sw_topographicarea”. Substitute the table name as necessary.

• Repeat this procedure for the other OS MasterMap Topography Layer database tables.

CartographicText requires additional attributes to be added before running the SQL:

1. Next, run each of styling SQL scripts using the same procedure as above.

You can now go ahead and use the new stylesheets with the data.

Key SQL query principles

The SQL scripts were written to create the new style attributes as efficiently as possible. The SQL queries are based on the key principles detailed below:

• Rule order: The rule order is based on the descending total count of a discrete feature. This means that as each feature is assessed, fewer rules need to be parsed to get to a matching rule for the feature. The only exception is in the Topographic Area SQL queries where the rules for built environment features are blocked together above the rules for natural environment features.

• Minimal attributes: The rules try to examine as few attributes as possible. Consider, the following example rules:

  • WHEN descriptivegroup ~ ‘Building’ THEN ‘Building Fill’

  • WHEN descriptivegroup ~ ‘Building’ AND descriptiveterm = ‘Archway’ THEN ‘Archway Fill’

In this example, the second rule would never to be used, because every feature with “Building” in the descriptiveGroup would match the first rule and therefore be styled as “Building Fill”. To overcome this, we need to amend the first rule to take the descriptiveTerm into consideration.

• WHEN descriptivegroup ~ ‘Building’ AND descriptiveterm IS NULL THEN ‘Building Fill’

• WHEN descriptivegroup ~ ‘Building’ AND descriptiveterm = ‘Archway’ THEN ‘Archway Fill’

This change allows Archway features to pass the first rule and get styled by the second. However, this means that the first rule needs to examine both the descriptiveGroup and descriptiveTerm attributes, making it fractionally slower than the original rule. We have tried to keep the number of attributes that need to be checked as low as possible.

• Minimal rules: The greater the number of rules, the greater the time to process all the features. To minimize the number of rules, we used different database operators to make finding certain attribute values easier. Consider the following example descriptiveTerms:

  • Nonconiferous Trees (Scattered), Rough Grassland Scrub,Nonconiferous Trees Nonconiferous Trees,Rough Grassland,Scrub

If we would like all of these to be styled as “Nonconiferous Tree Fill”, one solution is to write three rules:

• WHEN descriptiveterm = ‘Nonconiferous Trees (Scattered),Rough Grassland’ THEN ‘Nonconiferous Tree Fill’

• WHEN descriptiveterm = ‘Scrub,Nonconiferous Trees’ THEN ‘Nonconiferous Tree Fill’

• WHEN descriptiveterm = ‘Nonconiferous Trees,Rough Grassland,Scrub’ THEN ‘Nonconiferous Tree Fill’

A better alternative is to use one rule that looks for “Nonconiferous Tree” or “Nonconiferous Tree (Scattered)” at any position of the descriptiveTerm.

• WHEN descriptiveterm ~ ‘Nonconiferous Trees’ OR descriptiveterm ~ ‘Nonconiferous Trees (Scattered)’ THEN ‘Nonconiferous Tree Fill’

If all of these features have a style_description of “Nonconiferous Tree Fill”, it does not matter at which position the “Nonconiferous Tree” is as it will always be styled as “Nonconiferous Tree Fill”.