Bland.Basemaps (Elixir Technical Drawing v0.2.0)

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Static base-layer data for geographic figures.

BLAND ships a hand-curated, low-resolution set of cartographic outlines suitable for schematic maps in the tradition of 1960s–80s technical reports. The data is embedded in the library — no downloads, no external assets, no runtime dependencies.

Fidelity

The shipped outlines are schematic, not cartographic. They have enough points to be recognizable at world scale but deliberately trade fidelity for small file size. For precise maps, import a simplified Natural Earth GeoJSON and pass the polylines to Bland.line/4 or Bland.polygon/4 directly.

Available layers

Earth (longitude ± 180°, latitude ± 90°)

  • :earth_coastlines — continental outlines and major islands
  • :earth_borders — simplified outlines of major countries
  • :earth_tropics — Tropic of Cancer, equator, Tropic of Capricorn, Arctic / Antarctic circles as labelled horizontal reference lines

Moon (selenographic longitude ± 180°, latitude ± 90°)

  • :moon_maria — simplified outlines of the major lunar maria (Imbrium, Serenitatis, Tranquillitatis, Crisium, Fecunditatis, Nectaris, Nubium, Humorum, Frigoris, Procellarum, Cognitum, Vaporum)

Use via Bland.basemap/3

fig
|> Bland.basemap(:earth_coastlines)
|> Bland.basemap(:earth_borders, stroke: :dashed)

fig
|> Bland.basemap(:moon_maria, hatch: :dots_sparse)

Programmatic access

features/1 returns the raw feature list for a layer, which you can feed directly into your own series calls for full control:

for %{name: n, points: pts} <- Bland.Basemaps.features(:earth_coastlines) do
  IO.puts("#{n}: #{length(pts)} points")
end

Each feature is %{name: String.t(), points: [{lon, lat}], closed?: bool}.

Summary

Types

feature()
layer()
resolution()

Functions

features(layer, resolution \\ :low)

Returns the list of features for a basemap layer.

layers()

All available layer names.

unzip(map)

Returns {xs, ys} for a feature, suitable for piping into Bland.line/4 or Bland.polygon/4.

Types

feature()

@type feature() :: %{
  name: String.t(),
  points: [{float(), float()}],
  closed?: boolean()
}

layer()

@type layer() :: :earth_coastlines | :earth_borders | :earth_tropics | :moon_maria

resolution()

@type resolution() :: :low | :high | :schematic

Functions

features(layer, resolution \\ :low)

@spec features(layer(), resolution()) :: [feature()]

Returns the list of features for a basemap layer.

For Earth layers (:earth_coastlines, :earth_borders), the optional resolution selects between the vendored Natural Earth datasets:

  • :low — 1:110m (default). Fast, small, recognizable at world scale.
  • :high — 1:50m. Detailed enough for regional views; ~2.8 MB of compiled data.
  • :schematic — BLAND's hand-curated schematic outlines.

:earth_tropics and :moon_maria ignore the resolution argument — their data isn't resolution-scaled.

Each feature is a map with :name, :points, and :closed? fields.

Raises ArgumentError for unknown layers.

layers()

@spec layers() :: [layer()]

All available layer names.

unzip(map)

@spec unzip(feature()) :: {[float()], [float()]}

Returns {xs, ys} for a feature, suitable for piping into Bland.line/4 or Bland.polygon/4.