These instructions are based on QGIS version 3.22.4 and assume you have set the default coordinate reference system to British National Grid (EPSG 27700).

Loading and displaying the GML supply

There are two ways to load the GML supply into QGIS: You can use drag and drop or the Data Source Manager.

Using drag and drop

To load the GML supply using drag and drop:

1. Open an existing QGIS project or create a new one.

2. In the file system on your computer system (for example, in Windows Explorer), select the GML data (.gz file).

3. Drag and drop the file directly into the QGIS UI.

4. In the Select Items to Add dialog:

If you use multiple screens, this dialog may open on another screen.

• Select each required layer or click Select All to select all layers.

• Check the Add layers to a group option.

This groups the layers by OSMM Topography Layer tile reference.

• Click Add Layers.

The GML data will now display in both the Layers panel and the map area.

Using Data Source Manager

To load the GML supply into QGIS using Data Source Manager:

1. Open an existing project or create a new one.

2. In the Layer menu, click Data Source Manager.
3. In the Data Source Manager dialog:

   • Select Vector from the data menu on the left.

   • In Source > Vector Dataset(s), click ‘…’, navigate to and select the GML on your computer.

   • Click Add.

1. In the Select Items to Add dialog:

If you use multiple screens, this dialog may open on another screen.

• Select each required layer or click Select All to select all layers.

• Check the Add layers to a group option.

This groups the layers by OSMM Topography Layer tile reference.

• Click Add Layers.

The data will now display in both the Layers panel and the map area.

Layer order and rendering

Data is typically grouped by tile reference in the Layers panel. If you open two or more OSMM Topography Layer layers simultaneously (for example, TopographicArea and BoundaryLine), you may need to reorder the layers to see the data correctly.

You can reorder layers using drag and drop. We recommend the following layer order: CartographicText, CartographicSymbol, TopographicPoint, BoundaryLine, TopographicLine and TopographicArea.

GML data limitations

Using GML data in QGIS is not always the best option. You should consider converting your data to another format (for example, shapefile) for the following reasons:

• When working with multiple tiles of 5km2 OSMM Topography Layer data, GML data does not always merge seamlessly.

• Rendering performance of GML data in QGIS is not as good as other formats, because GML data cannot be spatially indexed.

The sections that follow show you how to convert GML data to shapefile and how to apply a spatial index to shapefiles.

Converting GML to shapefile

To convert GML to shapefile in QGIS:

1. In the Layers panel, right-click on the layer you want to convert and click Export > Save Features As....

1. In the Save Vector Layer as… dialog:

   • Format: Select ESRI Shapefile.

   • File name: Click …, navigate to the folder in which you want to store the shapefile, name the file, and click Save.

   • Check the Add saved file to map option.

   • Click OK.

You can watch the export progress in the blue progress bar at the bottom of the QGIS UI. When the process is complete, the shapefile layers will display in the Layers panel and the map area.

1. Repeat steps 1 - 2 above for each layer (for example, TopographicLine, CartographicText…) that you want to convert.

Applying a spatial index to shapefiles

When working with shapefiles, we recommend you apply a spatial index to the data, particularly when loading large or national sets of data. This significantly improves performance when rendering and panning the data.

To apply a spatial index to a shapefile in QGIS:

1. In the Layers panel, right-click on the shapefile layer you want to index and click Properties in the context menu.

1. In the Layer Properties dialog:

   • Select Source in the navigation menu on the left.

   • In Geometry click Create Spatial Index.

   • Click OK to close the confirmation dialog.

   • Click Apply and then OK.

Your shapefile layer will now be spatially indexed; this improves rendering and querying performance.

1. Repeat steps 1 and 2 above for each layer you want to create an index for (for example, TopographicLine, CartographicText…).

You can use the Astun Technology Loader to convert GML 2.1.2 data to other geospatial and non- geospatial formats.

This is a free, open-source loader for geographic data in GML and KML formats. It is written in Python and uses OGR 1.9. source data to output to any format supported by OGR, for example, shapefile and MapInfo TAB.

The loader was last updated in September 2022. Installation files and guides for the loader, including configuration examples, are available from the AstunTechnology/Loader GitHub repository.

These instructions are based on ArcMap version 10.8.1. and assume you have set the default coordinate reference system to British National Grid (EPSG 27700).

Loading and displaying the GML supply using the Quick Import tool

You can import GML data into ArcMap using the Quick Import tool that converts the GML into file geodatabase (.gdb).

To load GML data into ArcMap:

1. Open ArcCatalog and click and (ArcToolbox icon) in top toolbar to open the ArcToolbox.

1. In ArcToolbox, expand Data Interoperability Tools and click Quick Import.

1. In the Quick Import dialog, click … (next to the Input Dataset field), and navigate to and select your OS MasterMap Topography GML data.

1. In the Specify Data Source dialog:

   • Format: GML SF-0 (Geography Markup Language Simple Features Level SF-0 Profile) will be detected automatically.

   • Coord. System: Enter British_National_Grid or click … and select it in the dialog.

   • Click OK.

1. In the Quick Import dialog:

   • Output Staging Geodatabase field: Click (file browser icon), navigate to and name the file geodatabase (.gdb) folder, and click Save.

   • Click OK to start the Quick Import.

When the import process is complete, a message will display in ArcCatalog. To display the GML data in ArcMap:

1. Open an existing project or create a new one.

1. In the Add Data dialog:

   • Select the layers you want to load. You can select multiple layers at the same time to save repeating these steps for each layer in the file geodatabase.

   • Click Add.

Your geodatabase layers will now display in both the Table of Contents panel and the map area.

Loading and displaying shapefiles

As an alternative to using ArcMap’s Quick Import tool (previous section), you can convert your GML data to shapefile using FME and QGIS, and then add the shapefiles directly to ArcMap.

To load shapefiles into ArcMap

1. Open an existing project or create a new one.

1. In the Add Data dialog:

   • Navigate to the shapefiles you want to load. If the relevant folder does not display, click (Connect to Folder icon) and navigate to the file geodatabase folder from there.

   • Select the shapefiles that you want to load. You can select multiple layers at the same time to save repeating these steps for each shapefile.

   • Click Add.

Your shapefiles will now appear in both the Table of Contents panel and the map area.

You may need to reorder the layers to see the data correctly. You can reorder layers using drag and drop. We recommend the following layer order: CartographicText, CartographicSymbol, TopographicPoint, BoundaryLine, TopographicLine and TopographicArea.

These instructions are based on Cadcorp SIS Desktop Express 9.0.2511 and assume you have set the default coordinate reference system to British National Grid (EPSG 27700). These instructions also work for the fully licenced version of Cadcorp SIS Desktop.

Loading and displaying the GML supply

There are two ways to load the GML supply into Cadcorp SIS Desktop: You can use drag and drop or add and overlay.

Using drag and drop

To load and display the GML supply using drag and drop:

1. Open an existing project or create a new one.

2. In the file system on your computer system (for example, in Windows Explorer), select the GML data (.gz file).

3. Drag and drop the file directly into the Map area in Cadcorp SIS Desktop.

Data processing will begin automatically. You can monitor the progress by watching the spinning blue circle in the bottom left of the UI.

When processing is complete, the data will display in the Maps panel and Map area.

Cadcorp produces their own OS MasterMap Topography styling, which automatically styles your OMMM Topography data. If you cannot see your data, zoom to > 1:4,000 scale and it should become visible.

Adding an overlay

To load and display the GML supply by adding an overlay:

1. Open an existing project or create a new one.

2. From the Home tab, click Add Overlay.
3. In the Overlay Types dialog:

   • Click Files in the left navigation menu.

   • Click File in the options on the right.

   • Click Next>.

1. In the File Browser dialog:

   1. Navigate to and select the GML data (.gz file) you want to load.

   2. Click Finish.

Data processing will begin automatically. You can monitor the progress by watching the spinning blue circle in the bottom left of the UI.

When processing is complete, the data will display in the Maps panel and Map area.

Cadcorp produces their own OS MasterMap Topography styling, which automatically styles your OMMM Topography data. If you cannot see your data, zoom to > 1:4,000 scale and it should become visible.

The following instructions are based on ArcGIS Pro version 2.8.1 and assume that you have access to and knowledge of the UK Data Loader and the Data Interoperability Extension to convert the supplied GML into a suitable ArcGIS Pro format.

Loading and displaying the GML supply using UK Data Loader

The UK Data Loader is an ArcGIS toolbox. It contains a set of tools that primarily allow loading of Ordnance Survey data into an ArcGIS workspace.

If the UK Data Loader is not already installed, we recommend you add the folder containing the toolbox into your documents. More information on installing the UK Data Loader is available in ESRI’s UK Data Loader User Guide. This guide also provides instructions for processing Change Only Updates (COU) for OSMM Topography Layer.

Using the UK Data Loader involves two steps: Converting the GML supply and loading the converted file geodatabase into ArcGIS Pro.

Converting the GML supply to file geodatabase

To load the GML data into ArcGIS Pro using the UK Data Loader:

1. Open an existing project or create a new one.

You may want to select a basemap for backdrop context.

1. From the View tab, select Catalog View.

1. In the Catalog view, navigate to the location in which your UK Data Loader toolbox is saved.

You may need to connect to the relevant folder using the Add Folder option in the Insert tab.

1. Open the toolbox, navigate to OS MasterMap Topography Layer > Load OSMM Topography Data, right- click on the script, and click Open in the context menu.

1. This will open the Geoprocessing panel in which you can set the parameters for running the script:

   • Source Data Folder: Navigate to and select the GML file(s) required.

   • Existing Destination Workspace: Navigate to and select the pre-existing file geodatabase (.gdb) folder to load the data into.

   • Logging File Folder: Navigate to and select a folder into which to save the log that will be created during data processing. This is important because any error messages will be captured here. These may help identify issues.

   • Feature Class / Table Prefix: Enter a prefix for your tables (for example, Topo_).

   • Create Annotation Line Features: Check this option if it is available and required. This checkbox option is only available in older versions of ArcGIS Pro/UK Data Loader.

This may take some time, depending on the number of 5km OSMM Topography Layer tiles being processed.

On completion, the OSMM Topography Layer data will be saved to the destination file geodatabase, which can then be loaded into the workspace by following the instructions in the next section.

Loading and displaying data from the file geodatabase

Having converted your GML data to file geodatabase using the UK Data Loader (or other tools listed in this guide), you can now load the OSMM Topography Layer GDB into your ArcGIS Pro workspace.

To load and display the file geodatabase in an ArcGIS Pro workspace:

1. Open an existing project or create a new one.

You may want to select a basemap for backdrop context.

1. From the Map tab, select Add Data.

1. In the Add Data dialog, navigate to and select the file geodatabase (.gdb) containing the OSMM Topography Layer data, and then click OK.

1. In the selected file geodatabase (.gdb) select the feature classes that you want to load and then click OK.

You can select multiple feature classes at once to save repeating these steps for all the OSMM Topographic Layer features.

Your OSMM Topography Layer feature classes will now appear in both the Contents panel and map area.

You may need to reorder the layers to see the data correctly. You can reorder layers using drag and drop. We recommend the following layer order: CartographicText, CartographicSymbol, TopographicPoint, BoundaryLine, TopographicLine and TopographicArea.

Loading and displaying shapefiles

As an alternative to using the UK Data Loader, you can load OSMM Topography Layer shapefiles directly into your ArcGIS Pro workspace. You need to first convert your GML data to shapefile.

Translation tools available in FME and QGIS to convert the GML data to shapefiles.

To load and display shapefiles in an ArcGIS Pro workspace:

1. Open an existing project or create a new one.

You may want to select a basemap for backdrop context.

1. From the Map tab, select Add Data.

1. In the Add Data window, navigate to and select the shapefiles (.shp) containing the OSMM Topography Layer data, and then click OK.

You can select multiple shapefiles at once to save repeating these steps for all the OSMM Topographic Layer features.

Your OSMM Topography Layer shapefiles will now display in both the Contents panel and map area.

You may need to reorder the layers to see the data correctly. You can reorder layers using drag and drop. We recommend the following layer order: CartographicText, CartographicSymbol, TopographicPoint, BoundaryLine, TopographicLine and TopographicArea.

These instructions are based on MapInfo Professional 2019 and assume you have set the default coordinate reference system to British National Grid (EPSG 27700).

The sections below provide instructions for both working with GML data and converting to MapInfo TAB.

Loading and displaying the GML supply

To load and display the GML supply directly in MapInfo Professional:

1. Open an existing workspace or create a new one.

2. From the Home tab, click Open > Universal Data.

1. In the Specify Data Source dialog:

   • Format: Select GML (Geography Markup Language).

   • Dataset: Click …, and navigate to and select the GML file (.gz) in the file browser.

   • Click OK.

1. In the Select Layers dialog, select the layers you want to load and click OK.

Your GML data will now display in the Maps panel and map area.

Converting GML to MapInfo TAB

To convert the GML supply to MapInfo TAB in MapInfo Professional:

1. Open an existing workspace or create a new one.

2. In the Home tab, click Open > Universal Data.
3. In FME Quick Translator, click Translate.
4. In the Set Translation Parameter dialog:

   • Reader Format: Select GML (Geography Markup Language).

   • Reader Dataset: Click …, and navigate to and select the GML file in the file browser.

   • Format: Select MapInfo TAB (MAPINFO).

   • Dataset: Click …, and navigate to and select the folder you want the translated data saved to.

   • Click OK.

You can watch the translation progress log in the FME Quick Translator. It will take some time; a single 5km tile of OSMM Topography Layer in GML format takes approximately 30 seconds. When the process is complete, a message similar to the example below will display.

1. You can now close the FME Quick Translator.

You can now load the translated data into MapInfo Professional as TAB format using the instructions provided in the following section.

Loading the converted MapInfo TAB files

To load the converted MapInfo TAB files in MapInfo Professional:

1. Open an existing workspace or create a new one.

2. From the Home tab click Open > Table.
3. In the file browser:

   • Files of type: Select MapInfo (*.tab).

   • Navigate to the folder in which you stored the converted MapInfo TAB files and select the layers you want to open.

   • Click Open.

Your MapInfo TAB data (.tab) will now display in the Maps panel and map window.

Merging multiple Tab files

In MapInfo Professional it is possible to merge the elements of two TAB files into one new table using the append function.

To merge two TAB tables:

1. Follow the steps in Converting GML to MapInfo TAB above for both files.

2. Select one of your tables in the Explorer panel.

3. In the Home tab click Append Rows.

1. In the Append Rows to Table dialog:

   • Append Table: Select the table that will be appended.

   • to Table: Select the table to append to

   • Click OK.

The data from one table will now have been appended into the other. You will need to save the table to retain the appended data. See below for instructions on how to do this.

To verify which table contains the appended data:

1. Right-click a table in the explorer and click Browse Table in the context menu.

The total number of rows in the table displays in the bottom bar; this value of will be considerably larger for the table that included the appended rows.

To save the table:

1. Select the table containing the appended rows in the explorer.

2. From the Table tab click Save > Save Table.

As an alternative, you can use the Save Copy As action to additionally retain the original, unmerged table.

1. In the Save Table confirmation dialog click Save to confirm your action.

Your table will now contain the data for both original TAB files; you can verify this by opening the table to check the contents.

Deleting duplicate entries from tables

There are several ways to delete duplicate entries from tables MapInfo Professional. Please refer to the MapInfo Professional documentation for guidance:

• How to find All Records With Duplicate Values in a Column in MapInfo Pro (precisely.com). This article describes how to use SQL queries.

• User Guide: Search for the Delete Duplicates Tool.

These instructions are based on FME Desktop 2022.1.1.

Loading and displaying the GML supply

To load and display the GML supply in FME Desktop 2022.1.1.

1. Open an existing workspace or create a new one.

2. From the Reader tab click Add Reader…

1. In the Add Reader dialog:

   • Format: Select OGC GML (Geography Markup Language).

   • Dataset: Click …, and navigate to and select the GML file (.gz) in the file browser.

   • Coord. System: Select ESPG: 27700 (British National Grid).

   • Click OK.
2. In the Select Feature Types dialog select the required layers and click OK.

This dialog may take a while to load. You can watch the progress in the green bar at the bottom left of the FME window.

Figure 53:FME Desktop Select Feature Types dialog

When processing is complete, your features will appear as readers in the FME workspace.

1. Right-click one of the feature readers and click Connect Inspector in the context menu.

The Inspector will automatically connect to the reader.

The Inspector will automatically connect to the reader.

1. Click the Inspector and then click the Run to this icon (green triangle above the inspector).

2. In the Translation Parameter Values dialog click Run.

You can watch the loading progress in the Translation Log below the main workspace.

When the run command has completed, the GML table and features will display in the Visual Preview area below the main workspace.

1. Repeat steps 5 to 7 above for each layer (feature type) you want to view.

Converting GML to shapefile

You can use FME to convert GML data to other geospatial and non-spatial formats. The instructions below demonstrate how to convert GML data to shapefile, but you can adapt them for different formats.

To convert GML to shapefile in FME Desktop:

1. Repeat Steps 1 to 4 of the previous section (Loading and displaying the GML supply).

2. From the Writers tab click Add Writer…

1. In the Add Writer dialog:

   • Format: Select ESRI Shapefile.

   • Dataset: Click …, and navigate to and select the folder in which to save your translated data.

   • Coord. System: Select ESPG: 27700 (British National Grid).

   • Click OK.

1. In the Select Feature Type dialog select the layers you want to convert and click OK.

This dialog may take a while to load. You can watch the progress in the green bar at the bottom left of the FME UI.

1. Connect each reader to its matching writer by dragging the grey triangle on the reader to the red triangle on the writer.

1. In the main toolbar click (Run icon) to start the translation.

1. In the Translation Parameter Values dialog, check that the source and destination file locations are correct and click Run.

You can watch the conversion progress in the Translation Log below the main work area. When the conversion is complete (indicated by a message similar to the one below), both the GML files and Shapefiles will be available in your chosen folders and in the navigator.

Obtaining OS MasterMap Topography Layer data

This getting started guide shows you how to load OS MasterMap Topography Layer into several commonly used geographical information system (GIS) applications.

Product formats

OS MasterMap Topography Layer is available the following formats:

• GeoPackage (area of interest – AOI – only)

• Vector tiles (MBTiles)

• Geography Markup Language (GML) 2.1.2

The GML download ZIP package contains a GZ (.gz) file, which does not require extraction and contains multiple GML (.gml) files.

The GML data is supplied in 5km2 tiles, but features are not clipped at the tile edges, resulting in what is called “hairy” tiles. All tiles contain six elements:

• Cartographic Symbol

• Cartographic Text

• Boundary Line

• Topographic Point

• Topographic Line

• Topographic Area

OS MasterMap Topygraphy Layer can be downloaded from the OS Data Hub.

Media

OS MasterMap Topygraphy Layer is not available via hard media supply.

Using GeoPackage and vector tile formats

This getting started guide focuses on using the product in GML and shapefile format.

For guidance on using the product in GeoPackage or vector tiles formats, please see the following generic getting started guides:

• Getting Started with GeoPackage.

• Getting Started with Vector Tiles.

This guide contains instrictions for the following GIS applications:

• QGIS

• ArcGIS Pro

• ArcMap

• Cadcorp SIS Desktop Express

• MapInfo Professional

• FME Desktop

• Astun Technology GML/KML Loader