(Back from holidays). Ok, there’s a philosophical choice here that sort of goes to the heart of what problem data packages in general are trying to solve:
I think the goal of the Geo Data Package should to facilitate similar usage, in which case supporting non-EPSG:4326 projections is necessary. This adds complexity to associated tooling, but it doesn’t really add complexity to the spec itself. Tooling can always reproject into EPSG:4326 by default to keep things simple for non-experts.
So, in this view, a data package is a wrapper around messy data, and it’s up to the person consuming the data to use tools that can translate it into something clean. The value that Data Package is providing is allowing that process to be automated: the data itself is provided in its original format, but it’s relatively straight forward to build a tool (eg, the Data Retriever) that uses the Data Package metadata to transform the data.
But this particular use case seems a bit of an oddity:
- The developer of the tool creates the Data Package metadata
- The tool then uses that metadata to transform the data at runtime, invisibly to the end user.
In other words, the Data Package isn’t really serving any interoperability goal here. It could just as easily be a proprietary format (or code), because neither the provider of the data nor the consumer actually interacts with it at all. (I get that there is a benefit in being able to use other Data Package-supporting tools as part of the behind-the-scenes workflow. It’s hard to assess how important that is, in the general case.)
At its extreme, a Spatial Data Package could support everything. But then, nothing would support Spatial Data Package, except possibly one tool…whose job would be to convert the resources indicated, into something more directly consumable, probably GeoJSON.
So, on this point:
Tooling can always reproject into EPSG:4326 by default to keep things simple for non-experts.
I just don’t think this is a great approach, because you could make that statement now - tools exist to convert spatial formats into something more useful to a non-expert. But where is that tooling? How does the non-expert know what tool they need, or how to use it? To me, the value of something like Spatial Data Package is the promise that you’re guaranteed something that is immediately useful. All the work of converting and reprojecting should be done at the upstream end: a consumer should not be exposed to such complexities.