cih-y2k/go-bbox

This package calculates and returns one or more bounding boxes using a coordinate point and radius in kilometers.

go-bbox

This package is an implementation of a geospatial bounding box algorithm located here.

go get -u github.com/umpc/go-bbox

• Earth's equatorial radius of 6,378,137 meters is used for compatibility with online mapping services such as:
  • Google Maps
  • Bing Maps
  • Mapbox
• Bounds that cross the antimeridian are represented using two bounding boxes.
• Bounds that cross the poles are represented using a single bounding box that has:
  • a min longitude of -180 degrees
  • a max longitude of 180 degrees

Example usage

package main

import (
  "fmt"

  "github.com/umpc/go-bbox"
)

func main() {
  // Finds the min/max points for a rectangular area, which will be 276.49km
  // southwest and northeast of the center point.
  bboxes := bbox.New(276.494742, bbox.Point{
    Latitude:  -14.2436432,
    Longitude: -178.1795257,
  })
  for _, bbox := range bboxes {
    fmt.Printf("%+v\n", bbox)
  }
}

Example output

{Min:{Latitude:-16.727437727172838 Longitude:179.2578499517392} Max:{Latitude:-11.759848672827163 Longitude:180}}
{Min:{Latitude:-16.727437727172838 Longitude:-180} Max:{Latitude:-11.759848672827163 Longitude:-175.61690135173924}}

This example shows how bounds that cross the antimeridian are represented.

Benchmark results

$ go test -bench=.
goos: linux
goarch: amd64
pkg: github.com/umpc/go-bbox
BenchmarkNewEmpty-8             10000000               181 ns/op
BenchmarkNYC-8                   5000000               263 ns/op
BenchmarkLondon-8                5000000               267 ns/op
BenchmarkMontevideo-8            5000000               268 ns/op
BenchmarkToloke-8                5000000               320 ns/op
BenchmarkSuva-8                  5000000               322 ns/op
BenchmarkNorthPole-8            10000000               200 ns/op
BenchmarkSouthPole-8            10000000               202 ns/op
PASS
ok      github.com/umpc/go-bbox 15.109s

• CPU: Intel Core i7-4790k
• Memory: DDR3-1600
• Go: 1.10.2

References:

• Bronshtein, Semendyayev, Musiol, Mühlig: Handbook of Mathematics. Springer, Berlin. ISBN-13: 978-3817120079.