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donSchoe/gist:f12fffb3584ee2b9042d

Created July 2, 2015 07:24
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epsg4326 latLonToPixels xy
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gistfile1.js
// JavaScript
// converts lat/lon to pixel x/y at zoom level 0 for 256*256 tile size , inverts y coord
function latLonToPixels(lat, lon) { // lat, lon: epsg:4326
var sinLat = Math.sin(lat * Math.PI / 180.0);
var pixelX = ((lon + 180) / 360) * 256;
var pixelY = (0.5 - Math.log((1 + sinLat) / (1 - sinLat)) / (Math.PI * 4)) * 256;
return { x: pixelX, y: pixelY }; // object with .x and .y
}
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donSchoe commented Jul 2, 2015

ps. multiplying with * 256 can be skipped, range [0,1] is good to work with, too.

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