Overview
ISO 19123-2:2018 - Geographic information: Coverage Implementation Schema (CIS) - defines a concrete, implementable and conformance-testable structure for digital coverages based on the abstract coverage model in ISO 19123. The standard specifies an interoperable coverage information schema suitable for encoding in multiple formats (for example GML, JSON, GeoTIFF, NetCDF, GMLJP2) and for use with coverage-oriented services such as the Web Coverage Service (WCS). CIS enables consistent representation down to individual “pixels” or “voxels” and supports partitioning and multipart encodings.
Key topics and technical requirements
- Coverage model: A concrete instantiation of the abstract ISO 19123 coverage concept (a feature that maps positions in a spatial/temporal domain to values).
- CoverageFunction: Defines how coverage values are computed or retrieved for direct positions.
- RangeType and RangeSet coherence: Rules for representing the set of values (bands, channels, measurements) and ensuring internal consistency.
- Specific coverage types: Implementations for many coverage subtypes including Discrete Coverage, MultiPointCoverage, MultiCurveCoverage, MultiSurfaceCoverage, MultiSolidCoverage, GridCoverage, RectifiedGridCoverage and ReferenceableGridCoverage.
- Encoding and representation rules:
- GML representation requirements and a GML application schema for coverages (GMLCOV).
- Multipart representation: mechanisms for combining a GML coverage description with externally encoded range sets (e.g., large binary payloads).
- Special-format requirements: guidance for formats with particular needs (e.g., GeoTIFF, NetCDF).
- Conformance and testing:
- Defined conformance classes (including abstract class A.1: gml-coverage and concrete classes A.2–A.4) and an abstract test suite for conformance testing.
- Metadata: Structured metadata elements to describe domain, range, CRS, and other coverage properties.
Practical applications and users
ISO 19123-2 is used where interoperable, precise representation of spatial/temporal data is required:
- GIS and remote sensing data providers encoding imagery, rasters, multi-dimensional arrays, or voxel models.
- Developers of geospatial data formats and encoders (GMLCOV, GeoTIFF, NetCDF).
- Implementers of web services that deliver coverages (WCS, WCPS) and client software expecting standards-compliant coverages.
- Data integrators, quality assurance teams and test labs using the conformance test suite to validate coverage interoperability.
- Standardization bodies and domain experts harmonizing multi-domain geospatial data exchange.
Related standards
- ISO 19123:2005 / ISO 19123-1 - abstract schema for coverage geometry and functions
- ISO 19136 (GML) - Geography Markup Language
- ISO 19103 - Conceptual schema language
- OGC Coverage Implementation Schema (OGC 09-146r2) - functionally equivalent source used to derive CIS
Keywords: ISO 19123-2, Coverage Implementation Schema, CIS, coverage, GMLCOV, GridCoverage, RangeSet, GeoTIFF, NetCDF, conformance testing.