[DONE] Getting list of COGs for a given quadkey

[mackdelany]

Howdy,

As far as I'm aware, there is no way to ask Titiler to query a MosaicJSON file and return a list of COGs that overlap a given quadkey. This would be helpful for our use case at CarbonCrop.

If this is correct (I may have missed something) and the community is happy, I will submit a PR to expose this functionality.

My initial inclination would probably be something like:

• Add a mosaicjson/cogs endpoint
• Have the endpoint require a quadkey query param
• Have the endpoint return all valid COG paths for the given quadkey

So a request like:

http://<titiler-host>/mosaicjson/cogs/?url=<path-to-mosaic-file>/mosaic.json&quadkey=311330301132

Might return something like:

[
      "s3://super-awesome-cog-1.tif",
      "s3://super-awesome-cog-2.tif",
      "s3://super-awesome-cog-3.tif"
]

Definitely keen to hear if there are other preferences / or reasons why this isn't a thing / this does exist and I've missed it.

Thanks

[mackdelany]

After thinking about this a little more I think it's probably better to use a bounding box or lat long, something like:

http://<titiler-host>/mosaicjson/cogs/{minx},{miny},{maxx},{maxy}

http://<titiler-host>/mosaicjson/cogs/{lon},{lat}

With Titiler returniing lists of COGs which encompass the bbox or lat long.

[vincentsarago]

We could add all those 3 endpoints

http://<titiler-host>/mosaicjson/{minx},{miny},{maxx},{maxy}/assets

http://<titiler-host>/mosaicjson/{lon},{lat}/assets

http://<titiler-host>/mosaicjson/{quadkey}/assets

[geospatial-jeff]

These would be really useful, would most of this code live in cogeo-mosaic?

[vincentsarago]

Yes you'll need to use {Backend}.asset_for_tile and {Backend}.asset_for_point methods
https://github.com/developmentseed/cogeo-mosaic/blob/master/cogeo_mosaic/backends/base.py#L119-L126

Note: for bbox search you'll need to add a bit more code to get a list of quadkey for the given bbox for the mosaic quadkey_zoom.

[vincentsarago]

Also Side note: we can get the list of assets used per tile/point in the response headers https://github.com/developmentseed/titiler/blob/master/src/titiler/mosaic/titiler/mosaic/factory.py#L250-L251

[mackdelany]

Cool, this would be great. I'll send a PR across tomorrow. Thanks!

[vincentsarago]

work done in #351 by @mackdelany 🙏

[vincentsarago]

@mackdelany I merged your PR but now I'm wondering if using /{quadkey}/assets is a good approach. What do you think about using /{z}/{x}/{y}/assets ?

[mackdelany]

Yeah I think that's a better approach. Thanks for updating so quickly!