D3.js geoAiry() Function

Last Updated : 18 Sep, 2020

The geoAiry() function in d3.js is used to draw the Airy’s minimum-error azimuthal projection from the given geojson data. This is a solution to the shape and area errors caused due to the minimization in a map projection.

Syntax:

d3.geoAiry()

Parameters: This method does not accept any parameters.

Return Value: This method returns the Airy’s minimum-error azimuthal projection.

Example 1: The following example draws the Airy’s minimum-error azimuthal projection of Asia.

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src="https://d3js.org/d3.v4.min.js"> 
    </script> 
    <script src= 
"https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
</head> 
  
<body> 
    <div style="width:1200px; height:1000px;"> 
        <center> 
            <h3 style="color:green"> 
                geoAiry Projection of Asia 
            </h3> 
        </center> 
        <svg width="800" height="500"> 
        </svg> 
    </div> 
    <svg width="400" height="300"></svg> 
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // geoAiry projection 
        var gfg = d3.geoAiry() 
            .scale(width / 1.5 / Math.PI) 
            .translate([width / 2, height / 2]); 
  
        // Loading the json data 
        d3.json("https://raw.githubusercontent.com/" + 
            "janasayantan/datageojson/master/" + 
            "geoasia.json", 
            function (data) { 
  
                // Draw the map 
                svg.append("g") 
                    .selectAll("path") 
                    .data(data.features) 
                    .enter().append("path") 
                    .attr("fill", "black") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff") 
            }); 
    </script> 
</body> 
  
</html> 

Output:

Example 2: The following example draws the Airy’s minimum-error azimuthal projection of the world.

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <script src="https://d3js.org/d3.v4.js"> 
    </script> 
    <script src= 
"https://d3js.org/d3-geo-projection.v2.min.js"> 
    </script> 
</head> 
  
<body> 
    <div style="width:700px; height:600px;"> 
        <center> 
            <h3 style="color:grey"> 
                azimuthal Projection of World 
            </h3> 
        </center> 
        <svg width="700" height="550"> 
        </svg> 
    </div> 
    <script> 
        var svg = d3.select("svg"), 
            width = +svg.attr("width"), 
            height = +svg.attr("height"); 
  
        // geoAiry projection 
        var gfg = d3.geoAiry() 
            .scale(width / 1.5 / Math.PI) 
            .translate([width / 2, height / 2]); 
  
        // Loading the json data 
        d3.json("https://raw.githubusercontent.com/" + 
            "janasayantan/datageojson/master/" + 
            "geoworld%20.json", 
            function (data) { 
  
                // Draw the map 
                svg.append("g") 
                    .selectAll("path") 
                    .data(data.features) 
                    .enter().append("path") 
                    .attr("fill", "green") 
                    .attr("d", d3.geoPath() 
                        .projection(gfg) 
                    ) 
                    .style("stroke", "#ffff"); 
            }); 
    </script> 
</body> 
  
</html> 