The 12 core projections.
From D3 in Depth book by Peter Cook.
Last active
March 14, 2019 22:03
-
-
Save d3indepth/a0113244d43bea9f0f12e0d39675d56b to your computer and use it in GitHub Desktop.
D3 core projections
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| license: gpl-3.0 | |
| height: 6350 | |
| border: no |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <head> | |
| <title>Geo (projection distortion)</title> | |
| </head> | |
| <style> | |
| body { | |
| font-family: "Helvetica Neue", Helvetica, sans-serif; | |
| font-size: 14px; | |
| color: #333; | |
| } | |
| canvas { | |
| border: 1px solid #eee; | |
| margin: 5px; | |
| } | |
| .description { | |
| margin: 10px 0; | |
| } | |
| </style> | |
| <body> | |
| <h1>D3 core projections</h1> | |
| <div class="description">Here are the 12 <a href="https://github.com/d3/d3-geo/blob/master/README.md#projections" target="_blank">core geographic projections</a> in <a href="https://d3js.org" target="_blank">D3</a> (version 4.2). Equal radius circles are drawn to highlight area distortion (e.g. see Mercator).</div> | |
| <div class="description">From <a href="http://d3indepth.com">D3 in Depth</a>.</div> | |
| <div id="content"></div> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/4.2.2/d3.min.js"></script> | |
| <script src="https://cdnjs.cloudflare.com/ajax/libs/d3-geo-projection/2.1.2/d3-geo-projection.min.js"></script> | |
| <script> | |
| var geojson = {}; | |
| var projections = [ | |
| {type: 'AzimuthalEqualArea', scale: 100}, | |
| {type: 'AzimuthalEquidistant', scale: 80}, | |
| {type: 'Gnomonic', scale: 100}, | |
| {type: 'Orthographic', scale: 160}, | |
| {type: 'Stereographic', scale: 100}, | |
| {type: 'Albers', scale: 120}, | |
| {type: 'ConicConformal', scale: 100}, | |
| {type: 'ConicEqualArea', scale: 100}, | |
| {type: 'ConicEquidistant', scale: 100}, | |
| {type: 'Equirectangular', scale: 80}, | |
| {type: 'Mercator', scale: 70}, | |
| {type: 'TransverseMercator', scale: 70}, | |
| ]; | |
| var circles = [[0, 0], [-90, 0], [-45, 0], [45, 0], [90, 0], [0, -70], [0, -35], [0, 35], [0, 70]]; | |
| var geoCircle = d3.geoCircle().radius(10).precision(1); | |
| var geoGraticule = d3.geoGraticule(); | |
| var width = 500, height = 500, globalScale = 1.2, yaw = 1; | |
| var yawScale = d3.scaleLinear().domain([0, width]).range([-180, 180]); | |
| function updateCanvas(d) { | |
| var context = this.getContext('2d'); | |
| var projection = d3['geo' + d.type]() | |
| .scale(globalScale * d.scale) | |
| .center([0, 0]) | |
| .translate([0.5 * width, 0.5 * height]) | |
| .rotate([yaw, 0, 0]) | |
| var geoGenerator = d3.geoPath() | |
| .projection(projection) | |
| .context(context); | |
| context.lineWidth = 0.5; | |
| // Graticule | |
| context.strokeStyle = '#ccc'; | |
| context.fillStyle = 'none'; | |
| context.setLineDash([1,1]); | |
| context.beginPath(); | |
| geoGenerator(geoGraticule()); | |
| context.stroke(); | |
| // World | |
| context.fillStyle = '#eee'; | |
| context.setLineDash([]); | |
| context.beginPath(); | |
| geoGenerator({type: 'FeatureCollection', features: geojson.features}) | |
| context.fill(); | |
| context.stroke(); | |
| // Circles | |
| context.strokeStyle = '#888'; | |
| context.fillStyle = 'none'; | |
| circles.forEach(function(center) { | |
| geoCircle.center(center); | |
| context.beginPath(); | |
| geoGenerator(geoCircle()); | |
| context.stroke(); | |
| }); | |
| // Projection label | |
| context.fillStyle = '#333'; | |
| context.fillText(d.type, 10, 20); | |
| } | |
| function update() { | |
| var u = d3.select('#content') | |
| .selectAll('canvas') | |
| .data(projections); | |
| u.enter() | |
| .append('canvas') | |
| .attr('width', width + 'px') | |
| .attr('height', height + 'px') | |
| .merge(u) | |
| .each(updateCanvas); | |
| u.exit().remove(); | |
| } | |
| // REQUEST DATA | |
| d3.json('ne_110m_land.json', function(err, json) { | |
| geojson = json; | |
| update(); | |
| }) | |
| </script> | |
| </body> | |
| </html> |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment