Graham McIntire
828814e767
- Replace deprecated xref:exclude with elixirc_options in vendor/oban_pro - Remove unused require Logger from 8 files - Pin bitstring size variables with ^ in simple_packing, wgrib2, complex_packing, section, nexrad_client, mqtt, and radar worker - Remove dead defp clauses (format/1 nil, depression/2 nil) - Rename Buildings.Parser type record/0 -> building_record/0 to avoid overriding built-in type - Remove redundant catch-all in candidate_detail.ex - Simplify contact_live/show.ex conditional based on type narrowing - Fix DateTime.from_iso8601 return pattern in vendor/oban_web - Upgrade phoenix_live_view to 1.1.31 - Drop --warnings-as-errors from precommit alias; known false positives from @after_verify-generated code in Elixir 1.20.0-rc.6 + PLV 1.1.x - Add credo --strict to precommit as replacement static-analysis gate
97 lines
3.1 KiB
Elixir
97 lines
3.1 KiB
Elixir
defmodule Microwaveprop.Canopy do
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@moduledoc """
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Tree-canopy heights from a 30 m global canopy-height grid (Potapov et al.
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2019, Lang et al. 2022, or any source able to produce 1° × 1° uint8
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per-pixel rasters).
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Tile format: `@samples × @samples` bytes, row 0 at the north edge,
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one byte per pixel = canopy height in meters (0–255). Filename
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`N{lat}W{lon}.canopy` mirrors the SRTM `.hgt` convention.
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Returns 0 m for points without a tile on disk so the lookup can be
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threaded through the path-clearance pipeline without raising on
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un-fetched areas (treat unknown as treeless).
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"""
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@samples 3600
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@spec tile_filename(float(), float()) :: String.t()
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def tile_filename(lat, lon) do
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lat_floor = floor(lat)
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lon_floor = floor(lon)
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lat_prefix = if lat_floor >= 0, do: "N", else: "S"
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lon_prefix = if lon_floor >= 0, do: "E", else: "W"
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lat_str = lat_floor |> abs() |> Integer.to_string() |> String.pad_leading(2, "0")
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lon_str = lon_floor |> abs() |> Integer.to_string() |> String.pad_leading(3, "0")
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"#{lat_prefix}#{lat_str}#{lon_prefix}#{lon_str}.canopy"
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end
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@doc """
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Returns the canopy height in meters at `lat, lon`, or 0 if no tile is
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on disk for that 1° square.
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"""
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@spec lookup(float(), float(), String.t(), keyword()) :: non_neg_integer()
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def lookup(lat, lon, tiles_dir \\ default_dir(), opts \\ []) do
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samples = Keyword.get(opts, :samples, @samples)
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path = Path.join(tiles_dir, tile_filename(lat, lon))
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case :file.open(path, [:read, :binary, :raw]) do
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{:ok, fd} ->
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result = read_height(fd, lat, lon, samples)
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_ = :file.close(fd)
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result
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{:error, _} ->
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0
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end
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end
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@doc """
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Batch lookup. Groups points by tile so each tile is opened once.
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Returns `%{ {lat, lon} => height_m }`. Missing tiles yield 0.
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"""
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@spec lookup_many([{float(), float()}], String.t(), keyword()) ::
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%{{float(), float()} => non_neg_integer()}
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def lookup_many(points, tiles_dir \\ default_dir(), opts \\ []) do
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samples = Keyword.get(opts, :samples, @samples)
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points
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|> Enum.group_by(fn {lat, lon} -> {floor(lat), floor(lon)} end)
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|> Enum.flat_map(fn {_tile_key, pts} -> read_tile_points(pts, tiles_dir, samples) end)
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|> Map.new()
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end
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defp read_tile_points([{lat0, lon0} | _] = pts, tiles_dir, samples) do
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path = Path.join(tiles_dir, tile_filename(lat0, lon0))
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case :file.open(path, [:read, :binary, :raw]) do
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{:ok, fd} ->
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result =
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Enum.map(pts, fn {lat, lon} = pt -> {pt, read_height(fd, lat, lon, samples)} end)
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_ = :file.close(fd)
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result
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{:error, _} ->
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Enum.map(pts, fn pt -> {pt, 0} end)
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end
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end
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defp read_height(fd, lat, lon, samples) do
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row = round((floor(lat) + 1 - lat) * (samples - 1))
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col = round((lon - floor(lon)) * (samples - 1))
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offset = row * samples + col
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case :file.pread(fd, offset, 1) do
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{:ok, <<h::unsigned-integer-size(8)>>} -> h
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_ -> 0
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end
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end
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defp default_dir do
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Application.get_env(:microwaveprop, :canopy_tiles_dir, "/data/canopy")
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end
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end
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