Propose to change name for tile_id field of ARD products

[Kirill888]

Current ARD products include a top-level property called tile_id, this maps to SceneId in case of Landsat imagery and to GranuleIdentifier (also referred as TILE_ID in some xml metadata files).

I think tile_id is a confusing name, my first guess was that it's a unique id for a spatial region that this dataset covers, like path,row in case of Landsat or MGRS code for Sentinel. It is not that however.

What this field contains is data provider supplied string describing a specific observation on a given day, it includes sensor information, location and time information, level of processing and any other information provider chose to include. The format is provider specific. For example Landsat Scene Id looks like this LT50970681987310ASA00, example for sentinel data: S2A_MSIL1C_20170105T013442_N0204_R031_T53NMJ_20170105T013443

This data is lineage related, essentially it's a unique identifier for a source dataset from which this ARD dataset was constructed. So I propose we put it somewhere under lineage subtree.

Two questions:

1. Do we need a unified name, or can we live with provider specific name

   • lineage.scene_id for Landasat
   • lineage.granule_id for Sentinel

2. If we need unified name, what should it be, some suggestions

   • lineage.provider_reference_code
   • lineage.provider_dataset_id

Names are really hard to change once they are backed in, tile_id has lot's of room for confusion and I would very much prefer we don't use that name.

Here is a definition from wikipedia:

A tessellation of a flat surface is the tiling of a plane using one or more geometric shapes, called tiles, with no overlaps and no gaps.

Is there notation from STAC that we can borrow?

@simonaoliver @jeremyh @omad @ASVincent @GypsyBojangles