Elevation Extension

Currently the GeoPackage Standards Working Group (SWG) is developing an extension to support the storing of elevation data in support of visualization and analysis operations[1]. We see this as a good thing because without it, there is no interoperable way to exchange elevation data in SQLite[2]. In the interest of simplicity, we are basing the design on the existing tile model. We use PNG files to store the elevation values as unsigned integers and there is an additional extension that supports the use of TIFF files to store floating point values.

So how does this extension stack up in my list of things that make a good extension?

• Clear use case? Check.
• Sound technical approach? We believe so.
• A commitment to implementation by multiple implementers? In progress...

Our next step is to conduct an interoperability experiment[3] to investigate the degree to which implementers are able to produce GeoPackages that conform to the extension and their software is able to use compliant GeoPackages effectively. We are in the planning stages now and are looking for participants. We plan to do the bulk of the work in January and February and present the results at the OGC Technical Committee Meeting in March 2016. 

If this experiment is successful, it proves both the technical approach and the commitment to implementation. At that point, the SWG will be ready to adopt the new extension.

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[1] The ongoing work is available at: https://github.com/opengeospatial/geopackage-elevation
[2] As with any other extension, if a client does not conform with it, it will not see the elevation data but it will be able to see the features and tiles as it always has.
[3] See the Activity Plan