Space and time cubes

[forman]

Is your feature request related to a problem? Please describe.

The following data cube data access use cases cannot run with best available runtime performance:

• Extraction of 1-D time series at given points or aggregated from given polygons
• Extraction of 2-D image data at given location and size (visualisation, WMTS tiles)
• Extraction of N-D sub cubes

This problem becomes obvious in xcube-viewer where we both request image RGB tiles and time series from same data cubes. One or the other lacks performance if dataset chunking is adjusted to either one of the use cases such as the (exaggerated) examples time=1,lat=512, lon=512 and time=512,lat=1, lon=1.

Describe the solution you'd like

We provide one or more cube instances that only differ in their chunking. Clients, such as xcube-server, will be configured to serve these cubes based on the identified use case.

Therefore we allow users to configure multiple cube instances per dataset identifier. A dedicated "space cube" could be a ZARR multi-resolution pyramid with chunking time=1,lat=<tile_height>, lon=<tile_width>. In addition there may be a dedicated "time cubes" and any other "space/time cubes".

Additional context

Problem became obvious and urgent by publishing global demo cubes produced by the EarthSystemDataLab (ESDL) project using xcube-server and xcube-viewer.

See also

• Rechunking tool Tool for cube rechunking and compression #15
• Pyramid levels tool Allow creating spatial pyramid levels #38
• Pyramids spec. Zarr spec for pyramid-type data #61