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radiantearth / stac-spec

SpatioTemporal Asset Catalog specification - making geospatial assets openly searchable and crawlable
https://stacspec.org
Apache License 2.0
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Difference between "assets" and "item_assets" properties #1044

Closed l0b0 closed 3 years ago

l0b0 commented 3 years ago

What is the semantic difference between these two in a collection? The collection spec documents assets as

Dictionary of asset objects that can be downloaded, each with a unique key.

Item assets look very similar, and I'm not sure which one I'm meant to be using. I'm a software developer completely new to geospatial dataset jargon.

m-mohr commented 3 years ago

The main distinction is that "Item Assets Definition" can't define an href and they basically give an overview over what assets a STAC Item contains. It is a bit like a schema for the assets in items.

Collection assets are collection-level assets that are not specific to an Item. E.g. a collection-wide preview, collection-wide metadata or processing details that have been used across all collection etc. It doesn't make much sense to repeat them in all Items.

The difference has not really anything to do with geospatial.

We are happy to accept PRs that improve the language and make the distinction more clear.

Let me know if this explanation is not clear enough and then I'm happy to re-open this issue.