Add provider type for GeoVolumes (e.g. 3D Tiles, I3S etc.)

[KatKatKateryna]

Is your feature request related to a problem? Please describe.
There seems to be no straightforward opportunity right now to create a provider for 3d tiles, as the format doesn't align with existing implemented provider types (e.g. Features, Tiles, etc). There seems to be a draft specification for 3D GeoVolumes, which is meant to cover most types of 3d geospatial data. There is also a technical document describing server behavior when dealing with 3d GeoVolumes. Both of these documents are drafts and I am not sure what's the current status of the standard.

Describe the solution you'd like
I would suggest the pygeoapi implementation can follow this proposed schema: https://docs.ogc.org/per/20-030.html#_a_3d_client with only minimum required responses from the server that are unlikely to be ever changed: Container and Tileset.json. Container provides spatial extent of the dataset, and Tileset.json provides 3DTiles-compliant description of the dataset (folder with GLTF / B3DM / etc. files). Pygeoapi server response doesn't need to provide the files itself as a response (at least for now), as most of 3DTiles loaders (e.g. DeckGL, CesiumJS) can handle it on their own with only Tileset.json.

Describe alternatives you've considered
No real alternatives, 3d tile format cannot be provided using existing pygeoapi provider types.

Additional context
Happy to chat about possible options if this is something you envision on the roadmap, or postpone until the standard solidifies.

[doublebyte1]

@KatKatKateryna thank you for bringing up this topic - I also think it would be great to have 3D capabilities on pygeoapi, and I am supportive of any of these approaches. Some observations:

• 3D tiles: Although it does not align with the OGC APIs, that does not mean it cannot be implemented in pygeoapi. I think it will need its own API class, and it will certainly different from the other APIS. The STAC API is a good example of this: https://github.com/geopython/pygeoapi/blob/master/pygeoapi/api/stac.py
• 3D GeoVolumes: The WG does not seem to be very active, but that should not stop us to implement at least the core, which as you noted is quite simple and should not change very much. The thing that worries me most about 3D GeoVolumes is the lack of client implementations and public servers deploying the Standard, which could be a challenge for developing a server. However, maybe some engagement with the WG could sort that out, and even revive the SWG a bit, as a potential side effect (:

[doublebyte1]

I am adding @photonbit and @PascalLike to this discussion!