[gdal-dev] How to wrap a zarr in a zip and read it with vsizip?

[Michael Sumner]

Agree with all this, unfortunately xarray was a bit late with PR 9543 that
provides a basis for implicit coordinates (and will hopefully feed down
into Zarr), and knowing the difference from the low basis NetCDF provided.

There's a lot to it, but my read is that xarray is the new and way better
NetCDF (and I mean really damn impressive and ambitious and general), but
because it's born in python it missed a lot of really key geospatial
foundations that we take for granted, and for various reasons don't flow
well from rasterio through xarray .

I have long seen a need for some pretty serious cross discipline reviews,
and many of those are happening but not always enough, especially with
generational overwork and "novelty" burnout.

Appreciate the discussion here a lot.
Cheers, Mike

On Thu, Feb 27, 2025, 19:53 Laurențiu Nicola <lnicola at dend.ro> wrote:

> Hi,
>
> While I agree with the sentiment, I'm not sure I agree about some of the
> details. It assumes that on ZARR ZIPs, you need to make twice as many
> reads, for the local file headers and for the data. But the information in
> the local header is already available in the central directory, so you can
> seek directly to the data. This assumption is then used throughout the
> analysis.
>
> But there are things I don't really like about the format, like the very
> flexible data model and physical organization, the implicit assumption that
> everything is lat/lon, and the lack of overviews. I'm also a bit skeptical
> about the Python ecosystem. My impression is that Zarr just tries (and
> manages) to be a better NetCDF.
>
> Laurentiu
>
>
> On Thu, Feb 27, 2025, at 06:06, Michael Sumner via gdal-dev wrote:
>
> Just clueing into why you might be working with this, have you seen this
> critique?  (was a bit shocked to see that this is apparently going forward
> for Sentinel 2, let alone that it was even considered!)
>
> https://github.com/csaybar/ESA-zar-zip-decision
>
> Also glad to see a working example outlined that I can follow, Thanks!
>
> Cheers, Mike
>
>
>
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