Support for reading TILE-interleaved COG

[kylebarron]

The GDAL COG driver supports three interleaving strategies: Band, pixel and tile.

• Pixel: Stores a contiguous chunk for all data of the tile, ordered as height, width, bands
• Band: stores every band separately in the COG. This means that in order to fetch all bands, you need to make one fetch per band.
• Tile: Stores a contiguous chunk for all data of the tile, but ordered bands, height, width

We currently support Pixel and Band interleaving, but should also support Tile interleaving.

Todo:

• Create a new file in geotiff-test-data with tile interleaving
• Create a new test case here for reading that file.
• Update data fetching code to support reading an entire chunk for tile interleaved.
• Update docs for downstream code to interpret the data in correct band order

[weiji14]

Additional notes (mostly for myself). Illustrations from here:

Interleave	Description	PlanarConfiguration	Illustration
Pixel	BIP (Band Interleaved Per Pixel)	1 (Chunky)
Band	BSQ (Band SeQuential)	2 (Planar)
Tile	BIL (Band Interleaved per Line)1	2 (Planar)

How does one determine whether the interleave is BAND or TILE if they are both stored as PlanarConfiguration=2(Planar) in the TIFF tag? Edit: I just needed to scroll down - we need to parse the GDAL header ghost area

Footnotes

1. when block height = 1 ↩

[weiji14]

How does one determine whether the interleave is BAND or TILE if they are both stored as PlanarConfiguration=2(Planar) in the TIFF tag? Edit: I just needed to scroll down - we need to parse the GDAL header ghost area

Maybe we should move this issue to async-geotiff? But open a new issue in async-tiff to support parsing such ghost areas.

[kylebarron]

Thanks for the notes @weiji14!

Good to know that the effective interleaving is stored in the ghost area. So I suppose this depends on #201 being implemented first.

I figure maybe it would be possible to infer TILE or BAND interleaved just based on PlanarConfiguration=2 and the length of the TileByteOffsets array, but better to do it explicitly based on the ghost area.