convert from long/lat to google mercator (or EPSG:4326 to EPSG:900913)

degress2meters.js

// See https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames for more details.

var degrees2meters = function(lon,lat) {
        var x = lon * 20037508.34 / 180;
        var y = Math.log(Math.tan((90 + lat) * Math.PI / 360)) / (Math.PI / 180);
        y = y * 20037508.34 / 180;
        return [x, y]
}

x= -77.035974
y = 38.898717

console.log(degrees2meters(x,y))

// should result in: -8575605.398444, 4707174.018280

I m new in GIS. Result contain metric result like meters, but in google maps, latitude and longitude needs from me.

How does result convert to latitude longitude? Please, can you help this stituation?

Hi,

As would be the inverse function?
Convert EPSG:900913 to EPSG:4326
Anyone know the solution?

Thank you very much for your help.

for c/c++ lovers:

#define DEGREE_TO_METER(Y) (log(tan((90.0 + (Y)) * M_PI / 360.0)) / (M_PI / 180.0))*111319.490778
#define DEGREE_TO_METER_REVERSE(Y) (atan(pow(M_E, ((Y)/111319.490778)*M_PI/180.0))*360.0/M_PI-90.0)

@flinawer - see https://gist.github.com/onderaltintas/6649521

Hello how i can convert EPSG:3857 coordinate to EPSG:4326 ?

@marzochi

You may still find the way to convert EPSG:3857 to EPSG:4326, this gonna help you.
https://epsg.io/transform#s_srs=3857&t_srs=4326

how to convert from projection to lon/lat ?

are there ways to convert a geojson 3857 coords to 4326?
doing it with r and java but cant find a way that would solve the propblem
epsg.io is perfect for single data,
function trans2(){

   var test_x = document.getElementById("test_x").value;
   var test_y = document.getElementById("test_y").value;

   var ll2=new OpenLayers.LonLat(test_x, test_y).transform(
			new OpenLayers.Projection("EPSG:900913"), 
			new OpenLayers.Projection("EPSG:4326")
			);
   	      
   $("#test_ll_x").val(ll2.lon);
   $("#test_ll_y").val(ll2.lat);

}

is cool for java

but would like to know ways to do it in R

@MightyTedKim

Here's my general workflow for transforming a CRS in R.

With some GIS file (shp, gpkg, etc):

library(sf)
library(dplyr)
filepath <- system.file("shape/nc.shp", package="sf")
st_read(filepath) %>%
  st_set_crs(4326) %>% 
  st_transform(3857)

With a CSV:

df <- read.csv("some_csv.csv")
df %>% 
  st_as_sf(coords = c("lat_col", "lng_col")) %>% 
  st_set_crs(4326) %>% 
  st_transform(3857)

Thank you so much! It was really helpful.

console.log(degrees2meters(-180,-90)) //  [-20037508.34, -Infinity]

Can you please help with converting meters to lat long?

@Us77:

The C++ macro posted above works well for converting meters to lat/long degrees: #define DEGREE_TO_METER_REVERSE(Y) (atan(pow(M_E, ((Y)/111319.490778)*M_PI/180.0))*360.0/M_PI-90.0) (Thanks @jiangfeng79!)

Should be trivial to adapt to Python.