User Guide - Digimap

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This chapter has discussed the themes of OS MasterMap Topography Layer and outlined the contents of each theme. It explained how Ordnance Survey allocates a feature to one or more themes. This helps the customer to understand which theme a feature is likely to be found in and also why some features may appear in a theme that may not seem logical on first appearance. The next chapter discusses the types of geometry used to represent features and the attributes that come with each feature type. OS MasterMap Topography Layer user guide chapter 4 v1.3 – 07/2007 © Crown copyright Page 40 of 140
Chapter 5 OS MasterMap Topography Layer feature types and attribution Each OS MasterMap Topography Layer feature is represented as either a point, line or a polygon. These four types are further divided into six feature types to give a further refinement to reflect the different types of geographic or non-geographic function the line, point polygon or text represents. Point features There are three types of point feature: • Topographic point features that represent topographic detail and spot heights. • Cartographic symbol point features that store information about the location and type of symbology used when rendering OS MasterMap graphically. • Cartographic text point features that define the content and placement of text when rendering OS MasterMap graphically. Line features There are two types of line feature: • Topographic line features representing topographic information and inferred topographic area boundaries such as polygon closing links. • Boundary line features representing the boundaries of administrative areas. Polygon features There is one polygon feature type: • Topographic area features representing topographic information. The value of assigning features to data types Assigning each feature to data feature type creates a logical way for GIS to handle the data and reflects how GIS typically like to handle geometric data by having separate tables for each geometric type. There can be six separate, smaller tables rather than one large table. As there are different types of geometry and different types of features, having different data types allows each type to have its own particular set of attribution. It would not make any sense, for example, to have an attribution of a calculated area value for a line or point feature as these by their very nature do not have areas to measure. By having this particular structure, Ordnance Survey can provide more meaningful and more detailed attribution. Attribution Each feature comes with a set of attribution. Attribution provides additional information about the feature. This information could relate to the real-world object the feature represents or it could relate to the properties of the feature itself. For example, the theme the feature belongs to is an attribute, as is the TOID. The descriptive group is a property of the real-world object; the TOID is a property assigned to the feature. This chapter explains each attribute provided with OS MasterMap Topography Layer features and its purpose or value to the customer. The ranges of values that are associated with the attribute are listed in the technical specification. Each feature type has a different combination of attributes. Some are optional and some may occur multiple times on the same feature. Table 4 shows the attribution available with each feature type. Many attributes are common to all features but some are specific to a particular type. OS MasterMap Topography Layer user guide chapter 5 v1.3 – 07/2007 © Crown copyright Page 41 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 10 and 11: Currently, national cover is availa
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 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
Page 64 and 65: Symbols ...........................
Page 66 and 67: Chapter 1 Key concepts This section
Page 68 and 69: Chapter 3 Theme definitions This ch
Page 70 and 71: Chapter 4 Feature attribution In OS
Page 72 and 73: CartographicSymbol Attribute Occurr
Page 74 and 75: Simple attribute name Type Descript
Page 76 and 77: Simple attribute name Type Descript
Page 78 and 79: Chapter 6 Attribute values Attribut
Page 80 and 81: The following table clarifies the u
Page 82 and 83: Descriptive group Feature type Desc
Page 84 and 85: Make Descriptive group Feature type
Page 86 and 87: Chapter 7 Geometry and topology Int
Page 88 and 89: 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
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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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