Map Tile Scraper

Scrapes tiles from a tileserver and stitches them into a full size map. Tested with OpenStreetMap and Google Maps tile servers.

Requirements

• Node.js

Usage

• Run npm install to install dependencies.
• Copy parameters.example.json to parameters.json
• Fill in parameters.json with your tiles and desired configuration options
• Run node scrapeTiles.js
• Run node stitchTiles.js
• Check out.png to see if a map was properly stitched
• Run node distortMap.js to convert the Mercator projection to Equirectangular (uv = lat/lng) projection

How to texture this around a sphere

Apply the distorted map to a sphere where the UVs are equally spaced.

Alternatively, you can use the Mercator projection out.png map, transforming the coordinates with the following shader code.
See the following link for more details about the Mercator projection used by OpenStreetMap and Google Maps.

float2 latlng2xy_d(float2 latlng)
{
  float x = (1.0 - log(tan(latlng.y * M_PI / 180.0) + 1.0 / cos(latlng.y * M_PI / 180.0)) / M_PI) / 2.0;
  float y = (latlng.x + 180.0) / 360.0;
  return float2(1.0 - x, y);
}

TODO:

• Fix aspect ratio of Equirectangular projection.