Update retiling workflow to reflect current best-in-space workflow

[dhardestylewis]

• Update retiling workflow to reflect current best-in-space workflow

Include table describing 3 issues GDAL commands must work to unify:

• pixeltype ➡️ will be dropped before initiating terrain_aggregator

• colorinterp ➡️ will be dropped before initiating terrain_aggregator

• srid 👉 characterize GDAL limitations as begun in NOAA semi-annual terrain_aggregator DB details #81 (comment)

• Also one-off exceptions for Palette tiles ➡️ will be dropped before initiating terrain_aggregator

[dhardestylewis]

Begin drafting here the workflows to produce

• web tiles 👉 **slated 👍 **
• XYZ tiles 👉 **slated 👍 **

Also, begin including improvements such as:

• Cloud-Optimized GeoTIFFs 👉 **slated 👍 **
• Compression (DEFLATE?) 👉 for web portal we will keep these uncompressed
• Interpolation method - bilinear 👉 this will remain nearest neighbor to reduce concerns about synthetic data
• all the other relevant GDAL COG/GeoTIFF options

[dhardestylewis]

• incorporate hillshading to workflow
  does @brentporter have this code written up somewhere?

[dhardestylewis]

• there is still no single working script uploaded to https://github.com/dhardestylewis/terrain_aggregator