Paraphrased from the wikipedia article on Mercator projection: Given a “mapping sphere” of radius R, the Mercator projection (x,y) of a given latitude and longitude is: x = R * longitude y = R * log( tan( (latitude + pi/2)/2 ) ) and the inverse mapping of a given map location (x,y) is: longitude = … Read more
Your US json is already projected, and to show it you use a null projection: var path = d3.geoPath() //.projection(projection) Without defining a projection, your topojson/geojson coordinates will be translated to straight pixel coordinates. It just so happens that this particular topojson file has pixel coordinates that are within [0,0] and [960,600], almost the same … Read more
Albers projections can be a bit tricky if you don’t know the underlying transformations. Unless showing the US (for which the parameters of d3.geoAlbers are defaulted to), you’ll likely need to modify the parallels, rotation, and center. Standard Parallels This is an albers projection with its parallels set to 10 and 15 .parallels([10,15]), as in … Read more