PROJ4 Transformer

Description

A Transformer class contains all projections necessary for converting coordinates from one projection to another. This is a modular class that can be extended to add new projections as needed to reduce code size and improve performance. Both forward and inverse projections are default set to wgs84.

Extends the NadGridStore class to support grid lookups

Usage

Full Example

import { Transformer, injectAllDefinitions, injectAllEPSGCodes } from 'gis-tools-ts';

// Create a transform using a source and destination projection
const transform = new Transformer();
// inject all default definition projections. This is not memory efficient but ensures all
// projections are available
injectAllDefinitions(transform);
// Or add a specific projection
transform.insertDefinition(HotineObliqueMercator);
// inject all common EPSG codes. This is not memory efficient but ensures all EPSG codes are available
injectAllEPSGCodes(transform);
// Or add a specific EPSG code
transform.insertEPSGCode('EPSG_4326', EPSG_4326);
// If the transform requires a grid, this is how you add it.
transform.addGridFromReader(
  'BETA2007.gsb',
  new MMapReader(`${__dirname}/fixtures/BETA2007.gsb`),
);
// Set the source and destination projections
transform.setSource('EPSG_31466');
transform.setDestination('EPSG_25832');
// example forward projection
const forward = transform.forward({ x: 2559552, y: 5670982 });
// example inverse projection
const inverse = transform.inverse({ x: 349757.381712518, y: 5671004.06504954 });
Copy

Minimal Example only adding the Hotine Oblique Mercator

import { Transformer, HotineObliqueMercator, EPSG_8803 } from 'gis-tools-ts';

const transform = new Transformer(undefined, 'EPSG_8803', [HotineObliqueMercator], { EPSG_8803 });
// example moving from WGS84 to EPSG:8803
const forward = transform.forward({ x: 60.8, y: -132.2 });
Copy