Raster Reprojection

The NASA Blue Marble is reprojected using d3.geo.kavrayskiy7’s invert function. Jason Davies has since done some amazing work on reprojecting raster tiles.

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  background: #222;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/d3.geo.projection.v0.min.js"></script>
<script>

var width = 960,
    height = 500;

var projection = d3.geo.kavrayskiy7();

var path = d3.geo.path()
    .projection(projection);

var canvas = d3.select("body").append("canvas")
    .attr("width", width)
    .attr("height", height);

var context = canvas.node().getContext("2d");

var image = new Image;
image.onload = onload;
image.src = "readme-blue-marble.jpg";

function onload() {
  var dx = image.width,
      dy = image.height;

context.drawImage(image, 0, 0, dx, dy);

var sourceData = context.getImageData(0, 0, dx, dy).data,
      target = context.createImageData(width, height),
      targetData = target.data;

for (var y = 0, i = -1; y < height; ++y) {
    for (var x = 0; x < width; ++x) {
      var p = projection.invert([x, y]), λ = p[0], φ = p[1];
      if (λ > 180 || λ < -180 || φ > 90 || φ < -90) { i += 4; continue; }
      var q = ((90 - φ) / 180 * dy | 0) * dx + ((180 + λ) / 360 * dx | 0) << 2;
      targetData[++i] = sourceData[q];
      targetData[++i] = sourceData[++q];
      targetData[++i] = sourceData[++q];
      targetData[++i] = 255;
    }
  }

context.clearRect(0, 0, width, height);
  context.putImageData(target, 0, 0);
}

</script>

https://d3js.org/d3.v3.min.js

https://d3js.org/d3.geo.projection.v0.min.js