My objective here is to allow users to specify territories or regions given a background world-map overlay, which is an SVG generated from GeoJSON data using D3. I have done the part where the territories' points are pinpointed by the user, and an SVG is generated. This works well.
Now I would like to save the territory's coordinates, using the background map's projection, scale and translation. I saw a lot of documentation about translating GeoJSON data to SVG s, but nothing about the other way. Is it even possible ?
Thanks Ben Lyall, eventually I used the native SVG functions getTotalLength() and getPointAtLength() to convert my path to an array of top/left positions (in pixels), then d3's projection.invert() to translate them into coordinates.