GeoSpatial Affine Transformations for Humans
npm install geoaffinebash
npm install geoaffine
`basic usage
This library supports Geotransforms.
js
// or import Geotransform from "geoaffine/Geotransform.js";
import { Geotransform } from "geoaffine";const geotransform = [337934.4836350695, -0.14299987236417117, -0.5767759114507439, 7840518.464866471, -0.5767759114507457, 0.14299987236414916];
const { forward, inverse } = Geotransform(geotransform);
// convert pixel at origin (top-left corner) to coordinates in spatial reference system
forward([0, 0]);
[337934.4836350695, 7840518.464866471]
// convert point 200 pixels right and 100 pixels down
forward([200, 100]);
[337862.50605668797, 7840475.087262562]
// reverse above
inverse([337862.50605668797, 7840475.087262562], { floor: true })
[100, 100]
`advanced usage
$3
GeoTIFF ModelTransformationTag defines a 4x4 matrix of 16 parameters.
js
// or import ModelTransform from "geoaffine/ModelTransform.js";
import { ModelTransform } from "geoaffine";const matrix = [
-0.14299987236417117, -0.5767759114507439, 0, 337934.4836350695,
-0.5767759114507457, 0.14299987236414916, 0, 7840518.464866471,
0, 0, 0, 0,
0, 0, 0, 1
];
const { forward, inverse } = ModelTransform(matrix);
forward([2000, 2000]);
[336494.93206743966, 7839650.912788298]
inverse([336780.9318121680122, 7840804.46461119929832], { floor: true })
[0, 2000]
`$3
In order to avoid floating point arithmetic issues, you can use PreciseGeotransform and PreciseModelTransform,
which use preciso for mathematical calculations.
js
// or import PreciseGeotransform from "geoaffine/precise/Geotransform.js";
import { PreciseGeotransform } from "geoaffine";// or import PreciseModelTransform from "geoaffine/precise/ModelTransform.js";
import { PreciseModelTransform } from "geoaffine";
const geotransform = [337934.4836350695, -0.14299987236417117, -0.5767759114507439, 7840518.464866471, -0.5767759114507457, 0.14299987236414916];
const { forward, inverse } = PreciseGeotransform(geotransform);
forward([33.125, 67.825])
const xy = ["337890.62693810329012497625", "7840509.0581307472924654645"]
inverse(xy)
["33.125", "67.825"]
inverse(xy, { floor: true })
["33", "67"]
``