@millcrest/polygonize-wasm

WASM library for computing isolines, isobands, and GDAL-style polygon rasterization.

Installation

npm install @millcrest/polygonize-wasm

Functions

polygonize

Converts a raster grid to polygons where output boundaries align exactly with pixel edges (GDAL-style).

import { polygonize } from '@millcrest/polygonize-wasm';

const data = [
  1, 1, 2,
  1, 2, 2,
  3, 3, 2,
];

const result = polygonize(data, 3, 3);
// Returns GeoJSON FeatureCollection with one polygon per unique value

isobands

Computes filled contour polygons using marching squares interpolation.

import { isobands } from '@millcrest/polygonize-wasm';

const data = [
  0, 0, 0, 0,
  0, 2, 2, 0,
  0, 2, 2, 0,
  0, 0, 0, 0,
];

const result = isobands(data, 4, 4, [0, 1.5, 3]);

Options:

const options = {
  use_quad_tree: false, // default: true
  x_origin: 0,          // default: 0
  y_origin: 0,          // default: 0
  x_step: 1,            // default: 1
  y_step: 1,            // default: 1
};

const result = isobands(data, 4, 4, [0, 1.5, 3], options);

isolines

Computes contour lines using marching squares interpolation.

import { isolines } from '@millcrest/polygonize-wasm';

const result = isolines(data, 4, 4, [0, 1.5, 3]);

Same options as isobands.

Build

make build

Test

make test