To get the most from OS MasterMap data it is usually best to convert it from its supplied format, GML, to a format better suited to the software you are going to use it in. For our CAD users Digimap has been offering the DWG format for several months (see previous blog post); now we are offering a format that makes the data easier to use in GIS software.
Although Shapefile is still the most commonly requested GIS format it cannot handle the large file sizes (over 2GB) that could be requested from the Data Download service; an area of 100km2 in an urban centre would exceed this limit. We therefore turned to the File Geodatabase format that works in the two most commonly used GIS software applications, ArcGIS and QGIS. There is more information about Geodatabases on Wikipedia here: Wikipedia -ArcGIS Geodatabase
To select the File Geodatabase format, add some MasterMap to your basket in Data Download. Once in the basket you can click the down arrow in the Format column and change it from the default GML to File Geodatabase:
Geodatabase formats are the recommended formats for use in ArcGIS software, being the most efficient for data storage and analysis. The format supports the use of .lyr files for styling the data and EDINA has provided some for the MasterMap data downloaded from Digimap.
The data can be added to a map in ArcGIS and QGIS in the usual way, though in QGIS you need to use Add vector layer –> Directory rather than a Database as you may assume.
Styling information for both ArcGIS and QGIS has been provided by EDINA in .lyr and QML formats, these can be found at the bottom of Digimap’s help page for OS MasterMap. These representations give enough information to view the data in a style that OS MasterMap is commonly viewed in. The help page also contains a link to the official Ordnance Survey SLD styling information, please see the PDF that comes with the SLD files for information on how to use them.
There are help pages for adding styling information here:
If you require any help on using File Geodatabases from Digimap or any other dataset or format then please get in touch:
- Phone: 0131 650 3302
- Email: firstname.lastname@example.org