Overview
SIST EN ISO 19117:2015 (ISO 19117:2012), Geographic information - Portrayal is an international standard developed by CEN and ISO/TC 211 for geographic information and geomatics. It defines a conceptual schema for the portrayal of geographic information-specifically, the mapping of geospatial features to symbols, and the organization of those symbols and mapping functions into portrayal catalogues.
A primary benefit of this standard is the clear separation between geospatial feature data and its visual portrayal. This allows the same dataset to be depicted in multiple ways according to different user requirements or applications, without modifying the underlying data. This flexibility is crucial for interoperability in geographic information systems (GIS), cartographic product generation, and spatial data infrastructures.
Key Topics
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Conceptual Schema for Portrayal:
SIST EN ISO 19117:2015 specifies a comprehensive conceptual model using UML for describing how geographic features are mapped to visual or symbolic representations.
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Portrayal Functions:
Portrayal functions play a central role by associating geospatial features with symbols. The standard supports simple, conditional, and parameterized functions, accommodating various presentation needs.
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Symbol Definition and Structures:
The standard provides a framework for symbols, including simple, compound, complex, and parameterized symbols. Symbols can be reused and referenced externally, encouraging symbol consistency and resource sharing.
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Portrayal Catalogue:
A portrayal catalogue collates defined portrayal functions, symbols, and associated context. Multiple catalogues may exist to serve different datasets or user communities.
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Dataset Independence:
By keeping portrayal separate from feature data, datasets become more versatile and can be reused across multiple display or printing contexts.
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Contextual and Conditional Portrayal:
The model allows portrayal to adapt based on external context (e.g., display scale, viewing conditions like day or night) or specific feature attributes, enhancing presentation flexibility.
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Conformance and Extensions:
The standard defines core conformance classes for portrayal core, symbol, function, and catalogue, plus optional extensions for advanced symbol or function types.
Applications
SIST EN ISO 19117:2015 is widely applicable in the following areas:
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Geographic Information Systems (GIS):
Enables standardized map rendering, symbol management, and feature portrayal in GIS applications.
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Cartography:
Supports map design and production, allowing cartographers to consistently apply symbolization rules and easily exchange styling information.
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Spatial Data Infrastructures:
Facilitates data sharing and interoperability by ensuring portrayal definitions can be referenced independently from geospatial datasets.
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Web Mapping and Visualization:
Forms the conceptual foundation for web mapping services and systems (e.g., OGC Symbology Encoding, Styled Layer Descriptor in WMS), enabling dynamic and context-aware map rendering.
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Metadata and Cataloguing:
Works in conjunction with metadata standards (such as ISO 19115) to reference portrayal catalogues, enhancing dataset discoverability and usability.
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Custom Feature Visualization:
Empowers specialized domains and user communities to define and apply tailored symbolization and portrayal logic without data duplication.
Related Standards
For full implementation and integration, SIST EN ISO 19117:2015 is closely related to several other geographic information and metadata standards:
- ISO 19109: Rules for Application Schema
- ISO 19110: Methodology for Feature Cataloguing
- ISO 19115: Metadata
- ISO/TS 19103: Conceptual Schema Language
- ISO 19111: Spatial Referencing by Coordinates
- ISO/TS 19139: Metadata – XML Schema Implementation
- OGC Symbology Encoding & Styled Layer Descriptor (SLD): Web map styling protocols based on ISO 19117’s concepts
By adhering to SIST EN ISO 19117:2015, organizations and developers ensure their geographic information portrayal systems are robust, interoperable, future-proof, and suited for dynamic contexts across the geospatial domain.
