Make your own transit map with Google Maps

Google Maps continues to show what can be done with a few scripts, Photoshop and the satellite map view. Adrian Holovaty has created a how-to for people wanting to combine a city transit map with Google Maps.

Here's his "How I did it":

• Downloaded the CTA's official maps and combined them into a single image in Photoshop.
• Downloaded a bunch of Google map tile images for reference, noting the coordinates in their URLs (example), and spliced them together.
• Stretched and skewed the CTA map so that it was aligned as closely as possible to the Google map. This was the most time-consuming part of the process, and it didn't turn out as perfect as I'd have liked. I blame it on the CTA map designers for not being precise enough. :-)
• Chopped the aligned CTA map into 128-by-128-pixel tiles that matched their corresponding Google map tiles exactly -- by size, shape and coordinates.
• Wrote a server-side Python script that handles dispatching images. (Ideally a future version of the Greasemonkey script would embed the map images in itself directly.)
• Wrote the Greasemonkey script that brings it all together.
  

[via]