Geokit

Geokit is a PHP toolkit to solve geo-related tasks like:

• Distance calculations.
• Heading, midpoint and endpoint calculations.
• Rectangular bounding box calculations.

• Installation
• Reference
  • Distance
  • Position
  • BoundingBox
  • Polygon
  • Functions
    • Distance calculations
    • Transformations
    • Other calculations
• License
• Credits

Installation

Install the latest version with Composer.

composer require geokit/geokit

Check the Packagist page for all available versions.

Reference

Distance

A Distance instance allows for a convenient representation of a distance unit of measure.

use Geokit\Distance;

$distance = new Distance(1000); // Defaults to meters
// or
$distance = new Distance(1, Distance::UNIT_KILOMETERS);

$meters = $distance->meters();
$kilometers = $distance->kilometers();
$miles = $distance->miles();
$yards = $distance->yards();
$feet = $distance->feet();
$inches = $distance->inches();
$nauticalMiles = $distance->nautical();

A Distance can also be created from a string with an optional unit.

use Geokit\Distance;

$distance = Distance::fromString('1000'); // Defaults to meters
$distance = Distance::fromString('1000m');
$distance = Distance::fromString('1km');
$distance = Distance::fromString('100 miles');
$distance = Distance::fromString('100 yards');
$distance = Distance::fromString('1 foot');
$distance = Distance::fromString('1 inch');
$distance = Distance::fromString('234nm');

Position

A Position is a fundamental construct representing a geographical position in x (or longitude) and y (or latitude) coordinates.

Note, that x/y coordinates are kept as is, while longitude/latitude are normalized.

• Longitudes range between -180 and 180 degrees, inclusive. Longitudes above 180 or below -180 are normalized. For example, 480, 840 and 1200 will all be normalized to 120 degrees.
• Latitudes range between -90 and 90 degrees, inclusive. Latitudes above 90 or below -90 are normalized. For example, 100 will be normalized to 80 degrees.

use Geokit\Position;

$position = Position::fromXY(181, 91);

$x = $position->x(); // Returns -179.0, normalized
$y = $position->y(); // Returns 89.0, normalized

BoundingBox

A BoundingBox instance represents a rectangle in geographical coordinates, including one that crosses the 180 degrees longitudinal meridian.

It is constructed from its left-bottom (south-west) and right-top (north-east) corner points.

use Geokit\BoundingBox;
use Geokit\Position;

$southWest = Position::fromXY(2, 1);
$northEast = Position::fromXY(2, 1);

$boundingBox = BoundingBox::fromCornerPositions($southWest, $northEast);

$southWestPosition = $boundingBox->southWest();
$northEastPosition = $boundingBox->northEast();

$center = $boundingBox->center();

$span = $boundingBox->span();

$boolean = $boundingBox->contains($position);

$newBoundingBox = $boundingBox->extend($position);
$newBoundingBox = $boundingBox->union($otherBoundingBox);

With the expand() and shrink() methods, you can expand or shrink a BoundingBox instance by a distance.

use Geokit\Distance;

$expandedBoundingBox = $boundingBox->expand(
    Distance::fromString('10km')
);

$shrinkedBoundingBox = $boundingBox->shrink(
    Distance::fromString('10km')
);

The toPolygon() method converts the BoundingBox to an equivalent Polygon instance.

$polygon = $boundingBox->toPolygon();

Polygon

A Polygon instance represents a two-dimensional shape of connected line segments and may either be closed (the first and last point are the same) or open.

use Geokit\BoundingBox;
use Geokit\Polygon;
use Geokit\Position;

$polygon = Polygon::fromPositions(
    Position::fromXY(0, 0),
    Position::fromXY(1, 0),
    Position::fromXY(1, 1)
);

$closedPolygon = $polygon->close();

/** @var Position $position */
foreach ($polygon as $position) {
}

$polygon->contains(Position::fromXY(0.5, 0.5)); // true

/** @var BoundingBox $boundingBox */
$boundingBox = $polygon->toBoundingBox();

Functions

Geokit provides several functions to perform geographic calculations.

Distance calculations

• distanceHaversine(Position $from, Position $to): Calculates the approximate sea level great circle (Earth) distance between two points using the Haversine formula.
• distanceVincenty(Position $from, Position $to): Calculates the geodetic distance between two points using the Vincenty inverse formula for ellipsoids.

use function Geokit\distanceHaversine;
use function Geokit\distanceVincenty;

$distance1 = distanceHaversine($from, $to);
$distance2 = distanceVincenty($from, $to);

Both functions return a Distance instance.

Transformations

The circle() function calculates a closed circle Polygon given a center, radius and steps for precision.

use Geokit\Distance;
use Geokit\Position;
use function Geokit\circle;

$circlePolygon = circle(
    Position::fromXY(8.50207515, 49.50042565), 
    Distance::fromString('5km'),
    32
);

Other calculations

Other useful functions are:

• heading(Position $from, Position $to): Calculates the (initial) heading from the first point to the second point in degrees.
• midpoint(Position $from, Position $to): Calculates an intermediate point on the geodesic between the two given points.
• endpoint(Position $start, float $heading, Geokit\Distance $distance): Calculates the destination point along a geodesic, given an initial heading and distance, from the given start point.

License

Copyright (c) 2011-2020 Jan Sorgalla. Released under the MIT License.