OS MasterMap Topography Layer Getting Started with Styling Guide
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OS MasterMap Topography Layer contains features that represent objects in the physical environment, such as buildings, fields, fences, and letter boxes. It also includes intangible objects, such as county boundaries and the lines of mean high or low waters. There are over 500 million features in the product.
Ordnance Survey has developed a post-processing styling method that creates a cartographic styling utilizing discrete style attributes (style_code, colour_code, font_code and more) to ensure that users get the most out of the rich content available OS MasterMap Topography Layer. This guide describes this styling method and the related resources provided by Ordnance Survey, and shows you how to use the resources in various geographical information systems (GIS).
A number of methods have been developed to style OS MasterMap Topography Layer over time:
featurecode: This is the easiest method, but it provides only a limited number of styles and can result in mis-styled features when the same featurecode is used for multiple feature types.
featurecode and make: This method makes it possible to distinguish between features that share the same featurecode but have different values for ‘make’. A good example of this is Rail:
featurecode = 10167 AND make = ‘Manmade’
featurecode = 10167 AND make = ‘Natural’
This method is used in the open source stylesheets on the QGIS-UK/Styles GitHub repository.
descriptiveGroup, descriptiveTerm and make: How to use these three descriptive attributes is outlined in the OSMM Topography Layer - Standard Styling Specification.
descriptiveGroup, descriptiveTerm, make and physicalPresence: Using these four descriptive attributes provides access to the richness of the OS MasterMap Topography Layer data but is the most difficult method to implement.
Custom style attribute: A few Partners have implemented the creation of a new style attribute during the loading/processing of OS MasterMap Topography Layer. This gives features a discrete attribute on which to style that is far more efficient.
OS discrete styling attribute: Several years ago, we released Styled Layer Descriptors (SLDs) for OS MasterMap Topography Layer that used a discrete style attribute called os_cat. This attribute is a textual description (for example, buildingFill) that is created by post processing the data.
Multiple available styling methods made it difficult to provide uniform guidance for OS MasterMap Topography Layer, because the stylesheets look for a particular attribute field, which may not exist in the translated data. For example, descriptiveGroup can become descgroup or desc_group or DESCRIPTIVEGROUP.
The following resources provide additional information about the concepts in this guide:
Oracle INSTR Function - https://docs.oracle.com/cd/B28359_01/olap.111/b28126/dml_functions_1103.htm#OLADM564
PostgreSQL MVCC - http://www.postgresql.org/docs/current/static/mvcc-intro.html
PostgreSQL Pattern Matching - http://www.postgresql.org/docs/9.4/static/functions-matching.html
PostgreSQL Array Operators - http://www.postgresql.org/docs/9.4/static/functions-array.html
OGC Style Layer Descriptor - http://www.opengeospatial.org/standards/sld
