Best practices for creating STAC items with L2A single-band COGs vs stacked GeoTIF

[dimplejaiin]

Hi STAC team,

I'm working on organizing and exposing a dataset using STAC and wanted to get your thoughts on the best practices for structuring collections and items in a case where I have:

1. L2A-level processed single-band rasters stored as COGs, with each band (e.g., B02, B03, B04...) in a separate file.
2. The same tile at L2A level also exists as a stacked composite raster (not in COG format) where all bands are combined into a single file.

In addition:

• The directory structure differs for each version — the COG files are stored in one directory structure, while the stacked raster is in a separate path.

I’d like to understand:

• Should these be represented as two separate STAC collections (one for each representation), or as a single item with multiple assets (e.g., B02.tif, B03.tif, ..., composite.tif)?
• If using a single item, what is the best way to annotate the assets to clearly distinguish COG single-band vs stacked raster, especially given the storage locations differ?
• Would it make sense to represent the composite as a separate asset with a role like "overview" or "composite"?
• Are there existing examples or conventions in the STAC ecosystem for handling this type of dual-representation?

Thanks in advance for your guidance.

[gadomski]

Should these be represented as two separate STAC collections (one for each representation), or as a single item with multiple assets (e.g., B02.tif, B03.tif, ..., composite.tif)?

The most common pattern is a single item with multiple assets. Here's an example from USGS's Landsat STAC catalog: https://radiantearth.github.io/stac-browser/#/external/landsatlook.usgs.gov/stac-server/collections/landsat-c2l2-sr/items/LC09_L2SP_084068_20250706_20250707_02_T2_SR

If using a single item, what is the best way to annotate the assets to clearly distinguish COG single-band vs stacked raster, especially given the storage locations differ?

Storage location shouldn't matter, that's specified by the asset href, which can be anywhere. You can use bands to identify what bands are available on each asset.

Would it make sense to represent the composite as a separate asset with a role like "overview" or "composite"?

Sure!

Are there existing examples or conventions in the STAC ecosystem for handling this type of dual-representation?

Many L2 catalogs include a "visual" or "true color" asset which has RGB information, e.g. https://radiantearth.github.io/stac-browser/#/external/earth-search.aws.element84.com/v1/collections/sentinel-2-l2a/items/S2B_26ELC_20250708_0_L2A.

[dimplejaiin]

Thank You for the response 🙏 I’d like to clarify one more thing:

When representing both COG single-band and non-COG stacked GeoTIFF within a single item, what’s the best practice to annotate the assets to clearly distinguish between them?
Would explicitly setting the type field — for example, "type": "image/tiff; application=geotiff; profile=cloud-optimized" - be the recommended way to indicate COG compliance in such cases and "type": "image/tiff; application=geotiff" for GeoTIFF ?