Overview
ISO 19117:2012 - Geographic information - Portrayal defines a conceptual schema for describing how geographic data are visually presented. The standard specifies the structure and relationships for symbols, portrayal functions (the mapping from geospatial features to symbols), and the organization of these elements into portrayal catalogues. Its intent is to separate feature data from portrayal data so geographic datasets can be rendered independently of their original styling.
Key topics and technical requirements
- Conceptual schema: classes, attributes, associations and operations that model symbols, portrayal functions and their relationships.
- Portrayal functions: formal mappings that associate features or feature catalogues with symbols. Includes conditional and parameterized variants (e.g., rules-based or attribute-driven symbolization).
- Symbols: defined as simple, compound, complex or parameterized symbols. Parameterized symbols accept dynamic inputs from feature attributes.
- Portrayal catalogue: collections of portrayal functions, symbols and optional portrayal context used to manage and reuse symbology across datasets.
- Portrayal context: external factors (scale, viewing conditions, orientation) that influence selection or construction of symbols.
- Extensions and conformance: core schema plus optional extensions (conditional function extension, context extension, compound/complex symbol extensions, reusable symbol component extension, symbol parameter extensions, etc.). Conformance classes and an abstract test suite (Annex A) are specified for validation.
- Scope exclusions: the standard is not a symbol graphics standard (e.g., SVG), not a portrayal service spec (e.g., WMS), and does not cover non-visual portrayal, dynamic rendering, finishing rules, or 3D symbolization.
Practical applications and users
ISO 19117 is intended for:
- GIS and cartography software developers designing flexible rendering engines and styling systems.
- Standards implementers aligning with profiles such as OGC Symbology Encoding and Styled Layer Descriptor.
- Map designers and data providers who need portable, dataset‑independent symbol libraries and portrayal catalogues.
- Organizations building centralized style registries to ensure consistent cartographic representation across services and products.
Typical uses include centralized style management, attribute-driven symbolization (parameterized symbology), reusable symbol libraries, conditional rendering based on feature properties, and documenting portrayal rules for interoperability.
Related standards
Normative and related references include ISO/TS 19103, ISO 19107, ISO 19109, ISO 19110, ISO 19111, ISO 19115, ISO/TS 19139, and ISO/IEC 19501 (UML). These help integrate portrayal with broader geospatial schema, metadata and feature modelling.
