README

A PHP library that can be used to convert well-known text (WKT) projection information (like ones found in .prj files) to standard EPSG codes.

Prerequisites

• php >= 7.1
• ext-sqlite3:

Installation

Via Composer

This package can be installed easily with composer - just require the amestsantim/wkt2epsg package from the command line.

composer require amestsantim/wkt2epsg

Alternatively, you can manually add the voucherator package to your composer.json file and then run composer install from the command line as follows:

{
    "require": {
        "amestsantim/wkt2epsg": "^1.0"
    }
}

composer install

You can use it in your PHP code like this:

<?php
require __DIR__ . '/vendor/autoload.php';
use amestsantim\wkt2epsg\Translator;

$finder = new Translator();
echo "EPSG code is " . $finder->wktToEpsg('your wkt string');

If you are using it in Laravel, you can instantiate an object from the amestsantim\wkt2epsg\Translator class and access the conversion methods epsgToWkt() and wktToEpsg().

Usage

$finder = amestsantim\wkt2epsg\Translator();

$finder->epsgToWkt('epsg code');
// Equivalent WKT string or null (if not found)

$finder->wktToEpsg('wkt string');
// Equivalent EPSG code or null (if not found)

Documentation

The package works by querying the included SQLite database. The database has a table called 'epsg' which has mappings of Well-known Text strings to EPSG codeswhich. It has three columns:

• epsg
• name
• wkt

The the two conversion methods simply query the respective field and return the corresponding value from the other column (as per the method you are calling).

The sqlite database (epsg.db) is created by scrapping the Projected Coordinate Systems page (https://developers.arcgis.com/javascript/3/jshelp/pcs.html) from ESRI's arcgis website.

Since Projected Coordinate Systems page might get updated, I have included with this library, the python3 script that I used to scrape and generate the database. To do so, just run the script (esri_scrapper.py) from the esri directory.

I made this library because I had the need to identify the EPSG code of a shapefile (the CRS of the shapefile), especially when importing into PostGIS. I use the php-shapefile library which will read and return to you the raw WKT text from the .prj file but will not provide you with the EPSG SRID.

Contributing

Please feel free to submit a pull request, if you come up with any useful improvements.

Authors

• Nahom Tamerat

License

This project is licensed under the MIT License

Acknowledgments

• This package was inspired by sridentify