GeoPackage guidance

Contributed by: 
OGC Architecture Board (OAB)

The OGC Architecture Board (OAB) – comprised of elected OGC member experts – is tasked to ensure that candidate standards 1) align with the OGC Standards Baseline, 2) are compliant with the OGC Modular Specification policy (where appropriate), and 3) have considered the intersection with and dependencies related to other OGC standards and with partner international standards organizations such as ISO/TC 211.

In a recent OAB meeting, the GeoPackage 1.2 candidate standard was reviewed against the criteria above. The OAB reached a consensus that the candidate base standard is ready to be released to proceed to an approval vote in the OGC, but that the Elevation Extension does not yet meet the criteria. The OAB requested that the Elevation Extension include normative and informative references to one or more standard methods of encoding elevation, specifically methods that are consistent with coverages as defined in the OGC Coverages standard (also published as ISO 19123) and the ongoing harmonization of OGC and ISO coverage standards. This is not a repudiation of the work done to date. Rather, the OAB recognizes that elevation content is of general interest to OGC and ISO standards and thus the work should be as broadly applicable as possible. The expectation is that an updated Elevation Extension will be based on the work already drafted as part of GeoPackage 1.2 and will proceed in a rapid fashion through the OGC process. OGC encourages the participation of the developer community in finalizing this extension. Meanwhile, separation into two documents will allow the core standard to move forward without further delay while providing opportunity for the issues identified above to be addressed.

The GeoPackage Standards Working Group (SWG) began its first work in an environment that was somewhat unique in the OGC in that the implementer community was deeply involved in the development of the standard from the very beginning and the standard evolved in parallel with software testing. Now other OGC standards are following a similar model, much to the benefit of the geospatial community. While separation of the GeoPackage core from the Elevation Extension and revision of the latter specification is inconvenient for early implementers of the draft extension, the longer-term benefits of additional work on the extension will benefit not only the GeoPackage software community in terms of improved modularity, but also the OGC standards community as a whole by leading to a more consistent model for “elevation” across different formats and encodings.