D3.js geoStereographic() Function

Last Updated : 14 Oct, 2020

The JavaScript D3.js library provides interactive data visualizations for web page using HTML5, Scalable Vector Graphics, and Cascading Style Sheets.
The geoStereographic() function in d3.js is used to draw the stereographic projection.

Syntax:

d3.geoStereographic()

Parameters: This method does not accept any parameters.

Return Value: This method creates the Stereographic projection from given JSON data.

Example 1: The following example creates Stereographic projection of world with center at (0, 0) and without rotation.

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8" /> 
    <meta name="viewport" content="width=device-width,  
                initial-scale=1.0" /> 
</head> 
  
<body> 
    <div style="width: 700px; 
                    height: 500px;"> 
        <center> 
            <h3 style="color: black;"></h3> 
        </center> 
  
        <svg width="600" height="450"></svg> 
    </div> 
    <script src="https://d3js.org/d3.v4.js"> 
    </script> 
    <script src= 
    "https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Stereographic projection 
        // Center(0, 0) with 0 rotation 
        var gfg = d3 
            .geoStereographic() 
            .scale(width / 1.5 / Math.PI) 
            .rotate([0, 0]) 
            .center([0, 0]) 
            .translate([width / 2, height / 2]); 
  
        // Loading the json data 
        /* Used json file stored at  
        https://raw.githubusercontent.com/janasayantan 
         /datageojson/master/world.json*/ 
  
        d3.json("https://raw.githubusercontent.com/" 
            + "janasayantan/datageojson/master/world.json", 
            function (data) { 
                // Drawing the map 
                svg.append("g").selectAll("path") 
                    .data(data.features).enter() 
                    .append("path") 
                    .attr("fill", "DarkSlateBlue") 
                    .attr("d", d3.geoPath().projection(gfg)) 
                    .style("stroke", "#ffff"); 
            }); 
    </script> 
</body> 
  
</html> 

Output:

Example 2: In following example we will create Stereographicprojection of world with center at (-10, 20) and rotating 30 degree with respect to Y axis.

<!DOCTYPE html> 
<html lang="en"> 
  
<head> 
    <meta charset="UTF-8" /> 
    <meta name="viewport" content="width=device-width,  
                initial-scale=1.0" /> 
</head> 
  
<body> 
    <div style="width: 700px; 
                    height: 600px;"> 
        <center> 
            <h3 style="color: black;"> 
            </h3> 
        </center> 
  
        <svg width="500" height="450"></svg> 
    </div> 
    <script src="https://d3js.org/d3.v4.js"> 
    </script> 
    <script src= 
    "https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // Stereographic  projection 
        // Center(-10, 20) and 30 degree 
        // rotation w.r.t Y axis 
        var gfg = d3 
            .geoStereographic() 
            .scale(width / 1.5 / Math.PI) 
            .rotate([30, 0]) 
            .center([-10, 20]) 
            .translate([width / 2, height / 2]); 
  
        // Loading the json data 
        // Used json file stored at  
        /*https://raw.githubusercontent.com/janasayantan 
                     /datageojson/master/world.json*/ 
        d3.json("https://raw.githubusercontent.com/" 
            + "janasayantan/datageojson/master/world.json", 
            function (data) { 
                // Draw the map 
                svg.append("g").selectAll("path") 
                    .data(data.features).enter() 
                    .append("path") 
                    .attr("fill", "DarkSlategrey") 
                    .attr("d", d3.geoPath().projection(gfg)) 
                    .style("stroke", "#ffff"); 
            }); 
    </script> 
</body> 
  
</html> 