geotiff-tile

Generate a Map Tile from a GeoTIFF File.

install

npm install geotiff-tile

basic usage

import { createTile } from "geotiff-tile";

await createTile({
  // bounding box of tile in format [xmin, ymin, xmax, ymax]
  bbox: [-122.49755859375, 38.8520508, -120.06958007812499, 40.697299008636755],

  // spatial reference system of the bounding box
  // as a EPSG Code number
  bbox_srs = 4326,

  // geometry to clip by in GeoJSON format
  cutline: geojson,

  // spatial reference system of cutline
  cutline_srs,

  // set to higher number to increase logging
  debug_level = 0,

  // how many points to add to each side of the bounding box if reprojecting
  // optional, default is 100
  density = 100,

  // instance of geotiff.js
  geotiff,

  // function that accepts a pixel array of values of type
  // ({ pixel }: { pixel: number[] }) => number[]
  expr,

  // layout using xdim layout syntax
  // https://github.com/danieljdufour/xdim
  layout = "[band][row,column]",

  // resampling method
  method,

  // round pixel values to integers
  round,

  // optional
  // override default nested tile array types
  tile_array_types: ["Array", "Uint8ClampedArray"],

  // optional
  // if tile_array_types is not specified, choose
  // the strategy for deciding which type of arrays
  // auto - safest and default option, only uses typed array if it's sure there won't be any clamping
  // geotiff - use the same array types that geotiff.js uses (good if not stretching min or max)
  // untyped - use only untyped arrays
  // undefined - same as auto
  tile_array_types_strategy: "untyped",

  // over-ride default "no data" value in output tile
  tile_no_data: 0,

  // projection of the tile
  // as an EPSG code
  tile_srs: 3857,

  // tile height in pixel
  tile_height: 512,

  // width of tile in pixels
  tile_width: 512,

  // resolution of the tile
  // from 0 (lowest) to 1 (highest)
  tile_resolution: 0.5,

  // whether to use overviews if available
  // default is true
  // setting to false will mean the usage of the highest resolution data
  use_overview: false,

  // optional, default is false
  // enable experimental turbocharging via proj-turbo
  turbo: false
})

advanced usage

over-riding geotiff no data value

If for some reason your geotiff has values that should be treated as no data, but this isn't properly set in the metadata, you can over-ride the no data value

await createTile({
  geotiff,
  geotiff_no_data: -32767,
  // rest is the same
})

over-riding geotiff srs

If for some reason geotiff-tile can't parse the correct projection from your geotiff, you can manually specify the projection via the geotiff_srs parameter.

await createTile({
  geotiff,
  geotiff_srs: 3031,
  // rest is the same
})

image pixel coordinates and simple srs

You can also select pixels using a "simple" spatial reference system where the bottom left of your data is the origin [0, 0] and the top-right corner is [width, height]. This is inspired by Leaflet's Simple CRS.

await createTile({
  bbox: [128, 656, 144, 672],
  bbox_srs: "simple",

  // rest is the same
})