User Guide - Digimap

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Currently, national cover is available for the Topography, Address and ITN Layers. The format for most of the data is Geography Mark-up Language (GML). Address Layer 2 is available in GML and in Comma Separated Values (CSV) formats. The data is supplied in the zipped format, indicated by the suffix ‘GZ’ at the end of the file name. Table 1 below gives the approximate data volumes in the zipped GZ format for national cover. Due to the way different systems may store the unzipped data, it is not possible to provide file sizes for national cover in the unzipped format. Table 1: OS MasterMap data volumes Layer Size Topography 32 Gb Address Layer 1 and 2 2 Gb (GML) 1.4 Gb (CSV) ITN 440 Mb National cover for the Imagery Layer is due to be available in 2006. The current estimated sizes for the images only are: • 11 300 Gb for TIFF • 360 Gb for Mr SID or ECW • 660 Gb for JPEG Additional space should be allowed for metadata and registration files. The minimum system requirements to use the OS MasterMap online service are detailed on the Ordnance Survey website. For further information on the technical implications of implementing OS MasterMap please see Information sheet 3 – Technical implications from the implementing OS MasterMap series of documents from the Ordnance Survey website. Gaelic or Welsh names are also supported. A character set is available. The data model OS MasterMap vector products have a hierarchical structure. The highest level of the structure is the layer. Within each layer can be a series of themes. Within each theme there will be features deemed to belong to that theme. A feature can belong to more than one theme. This model is extensible at all levels. New layers can be added to OS MasterMap. New themes can be added to layers. New features can be added to themes. Each feature will have one or more versions of itself that demonstrate change to that feature over time. New versions of features replace existing features. Features that no longer exist can be deleted. The rest of this chapter discusses the main features of the first level of the model, the layer, and introduces the concepts of themes, features and attributes. OS MasterMap Topography Layer user guide chapter 1 v1.3 – 07/2007 © Crown copyright Page 10 of 140
Layers OS MasterMap is currently supplied in four layers. Each layer can be used independently of the others, although they are designed to integrate and complement each other. Topography Layer The Topography Layer was the first layer to be produced, in November 2001. The features within this layer are mainly features that appear in the landscape, such as buildings, land, water and roads (figure 4). It also includes administrative boundaries. These are not physically present in the landscape but are often important in relation to the physical features that are present in the real world. It is the most detailed layer, containing over 425 million features as of May 2006. Figure 4: OS MasterMap Topography Layer OS MasterMap Topography Layer user guide chapter 1 v1.3 – 07/2007 © Crown copyright Page 11 of 140
Page 2 and 3: OS MasterMap Topography Layer User
Page 4 and 5: Preface This user guide (hereafter
Page 6 and 7: Chapter 1 Introduction to OS Master
Page 8 and 9: The vector and raster data models T
Page 12 and 13: Address Layers OS MasterMap Address
Page 14 and 15: Imagery Layer The Imagery Layer com
Page 16 and 17: Chapter 2 Introduction to OS Master
Page 18 and 19: It is important for many applicatio
Page 20 and 21: Chapter 3 Feature life cycles and t
Page 22 and 23: One of the key differences between
Page 24 and 25: Joining of polygon features When tw
Page 26 and 27: The other type is a polygon closing
Page 28 and 29: Chapter 4 OS MasterMap Topography L
Page 30 and 31: A textual description is used for c
Page 32 and 33: Rail These are defined as features
Page 34 and 35: There are two situations where cons
Page 36 and 37: Figure 17 shows a sample of real-wo
Page 38 and 39: Table 3 Value of descriptive group
Page 40 and 41: This chapter has discussed the them
Page 42 and 43: Table 4: Attribution by feature typ
Page 44 and 45: Physical level The physical level a
Page 46 and 47: Text string Cartographic text that
Page 48 and 49: The advantages of supplying COU rat
Page 50 and 51: Supply of OS MasterMap Topography L
Page 52 and 53: Departed features are supplied in C
Page 54 and 55: Chapter 7 Change management and dat
Page 56 and 57: This is a more efficient way of sto
Page 58 and 59: Figure 28: Styling options with OS
Page 60 and 61:
Annexe A Administrative boundary al
Page 62 and 63:
OS MasterMap Topography Layer Techn
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Symbols ...........................
Page 66 and 67:
Chapter 1 Key concepts This section
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Chapter 3 Theme definitions This ch
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Chapter 4 Feature attribution In OS
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CartographicSymbol Attribute Occurr
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Simple attribute name Type Descript
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Simple attribute name Type Descript
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Chapter 6 Attribute values Attribut
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The following table clarifies the u
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Descriptive group Feature type Desc
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Make Descriptive group Feature type
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Chapter 7 Geometry and topology Int
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Example class model Rectangle A rec
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Polygon boundary duplication A brea
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Chapter 9 GML output format The OS
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For geographically chunked data, if
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For example: 12365.563,8975.676
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Schema descriptions The W3C-provide
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descriptiveGroup descriptiveTerm ma
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Property application logic This sec
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Chapter 11 Data supply service The
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Annexe A Glossary The purpose of th
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georectified imagery The georectifi
Page 110 and 111:
orthorectified imagery The Imagery
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Annexe B GML examples 1 A typical T
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Annexe C Cartographic style definit
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Fonts The gml2svg.xsl declares the
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Geometry: boundaryMereingChangeSy
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triangulationStationSymbol Style: s
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multiVegetationFillSymbol Style: st
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screeFillSymbol Style: stroke:#6666
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smallNonconiferousTreeFillSymbol St
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Definitions Transformation 1 Symbol
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Name: roughGrassAndMarshFillSymbol
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Name: roughGrassScatteredRocksAndHe
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nonconiferousTreesAndScrubPattern r
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Water bold Name - waterBoldLine str
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Parliamentary Name - parliamentaryL
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Acute accent on the following (for
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User Guide - Digimap

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