Generate a Map Tile from a GeoTIFF File.
npm install geotiff-tilebash
npm install geotiff-tile
`basic usage
js
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
$3
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
js
await createTile({
geotiff,
geotiff_no_data: -32767,
// rest is the same
})
`$3
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.
js
await createTile({
geotiff,
geotiff_srs: 3031,
// rest is the same
})
`$3
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.
js
await createTile({
bbox: [128, 656, 144, 672],
bbox_srs: "simple",
// rest is the same
})
`$3
You can cancel a request for tile data, by using an AbortSignal from an AbortController.
This signal is passed to geotiff-read-bbox, which then passes it to geotiff.js.
js
const controller = new AbortController();const promise = createTile({
signal: controller.signal
// rest is the same
})
// cancels the tile request above before the promise resolves
controller.abort();
``