Question

I have some geojson data for Japan, which I managed to position properly on a mercator projection, but I’m a bit lost as to how to position it properly using an albers projection, other than trial and error.

Is there a good tool to use?

blocks example: http://bl.ocks.org/4043986

long, lat for japan (wikipedia):

• latitudes 24° – 46°N,
• longitudes 122° – 146°E.

geojson link: https://gist.github.com/raw/4043986/f53b85ab0af1585cd0461b4865ca4acd1fb79e9f/japan.json

Answer 1

I found the answer looking through the repository – the tool is right there!

1. clone d3.js from the github repository.
2. edit /d3/examples/albers.html line 53 to point at your GEOJSON file:
3. Put the origin long / lat sliders to the center of your country / region (for me, it was 134° / 25°)
4. Change the paralells to be as close to the edges of your country / region.
5. adjust scale & offset to a nice size & position.

There are similar tools for the other projections.

edit: The repository has changed (and is constantly changing), so I’ve created a gist to preserve the example: https://gist.github.com/4552802

The examples are no longer part of the github repository.