DGGS.jl

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Remote data ​

access the remote DGGS pyramid Blue Marble:

julia
using DGGS
using Zarr
using GLMakie

store = zopen("https://raw.githubusercontent.com/danlooo/blue-marble.dggs.zarr/refs/heads/master")
p = open_dggs_pyramid(store)
┌ DGGSPyramid ┐
├─── branches ┤
  :dggs_s1 dims: dggs_i, dggs_j, dggs_n size: 4×2×5 layers: :Red, :Green, :Blue
  :dggs_s2 dims: dggs_i, dggs_j, dggs_n size: 8×4×5 layers: :Red, :Green, :Blue
  :dggs_s3 dims: dggs_i, dggs_j, dggs_n size: 16×8×5 layers: :Red, :Green, :Blue
  :dggs_s4 dims: dggs_i, dggs_j, dggs_n size: 32×16×5 layers: :Red, :Green, :Blue
  :dggs_s5 dims: dggs_i, dggs_j, dggs_n size: 64×32×5 layers: :Red, :Green, :Blue
  :dggs_s6 dims: dggs_i, dggs_j, dggs_n size: 128×64×5 layers: :Red, :Green, :Blue
  :dggs_s7 dims: dggs_i, dggs_j, dggs_n size: 256×128×5 layers: :Red, :Green, :Blue
  :dggs_s8 dims: dggs_i, dggs_j, dggs_n size: 512×256×5 layers: :Red, :Green, :Blue
  :dggs_s9 dims: dggs_i, dggs_j, dggs_n size: 1024×512×5 layers: :Red, :Green, :Blue
  :dggs_s10 dims: dggs_i, dggs_j, dggs_n size: 2048×1024×5 layers: :Red, :Green, :Blue
  :dggs_s11 dims: dggs_i, dggs_j, dggs_n size: 4096×2048×5 layers: :Red, :Green, :Blue
├─────── DGGS ┤ 
  DGGSRS:     ISEA4D.Penta
  Geo BBox:   Extent(X = (-180.0, 180.0), Y = (-90.0, 90.0))
└─────────────┘

Plot the pyramid:

julia
plot(p, :Red, :Green, :Blue; scale_factor=1/255)

A vertex of the icosahedron used for projection is near Gothenburg, Sweeden. This results into different oritentations of the DGGS zones, depending on which polyhedral face they belong to:

julia
using Extents
bbox = Extent(X = (10.5,12), Y=(57.5,59))
plot(p, :Red, :Green, :Blue; scale_factor=1/255, extent=bbox)

Subset a dataset with arrays at the same spatial resolution:

julia
ds = p[8]
┌ 512×256×5 DGGSDataset ┐
├───────────────────────┴──────────────────────────────────────────────── dims ┐
  ↓ dggs_i Sampled{Int64} 0:1:511 ForwardOrdered Regular Points,
  → dggs_j Sampled{Int64} 0:1:255 ForwardOrdered Regular Points,
  ↗ dggs_n Sampled{Int64} 0:1:4 ForwardOrdered Regular Points
├────────────────────────────────────────────────────────────────────── layers ┤
  :Red   eltype: Union{Missing, UInt8} dims: dggs_i, dggs_j, dggs_n size: 512×256×5
  :Green eltype: Union{Missing, UInt8} dims: dggs_i, dggs_j, dggs_n size: 512×256×5
  :Blue  eltype: Union{Missing, UInt8} dims: dggs_i, dggs_j, dggs_n size: 512×256×5
├──────────────────────────────────────────────────────────────────────── DGGS ┤ 
  DGGSRS:     ISEA4D.Penta
  Resolution: 8 (up to 6.55e+05 cells)
  Geo BBox:   Extent(X = (-180.0, 180.0), Y = (-90.0, 90.0))
└──────────────────────────────────────────────────────────────────────────────┘

Extract a band:

julia
a = ds.Blue
┌ 512×256×5 DGGSArray{Union{Missing, UInt8}, 3} Blue ┐
├────────────────────────────────────────────────────┴─────────────────── dims ┐
  ↓ dggs_i Sampled{Int64} 0:1:511 ForwardOrdered Regular Points,
  → dggs_j Sampled{Int64} 0:1:255 ForwardOrdered Regular Points,
  ↗ dggs_n Sampled{Int64} 0:1:4 ForwardOrdered Regular Points
├──────────────────────────────────────────────────────────────────── metadata ┤
  Dict{String, Any} with 7 entries:
  "missing_value" => 255
  "name"          => "Blue"
  "author"        => "NASA Earth Observatory"
  "source"        => "https://eoimages.gsfc.nasa.gov/images/imagerecords/73000/…
  "title"         => "October, Blue Marble Next Generation"
  "_FillValue"    => 0xff
  "published"     => "2004-10-1"
├──────────────────────────────────────────────────────────────────────── DGGS ┤ 
  DGGSRS:     ISEA4D.Penta
  Resolution: 8 (up to 6.55e+05 cells)
  Geo BBox:   Extent(X = (-180.0, 180.0), Y = (-90.0, 90.0))
└──────────────────────────────────────────────────────────────────────────────┘

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