GrassrootsMapping
Map Warper
Once you have a set of aerial photographs, you can stitch them into a digital map with Map Warper. You’ll get something like the image below.
Very important!
In order to correlate points in your images with points in the reference map, you need to be able to see features like trees, street corners, manholes, or whatever, in both the image and the map. However, for many areas this is impossible because the reference map doesn’t have these features. In general, even for well-mapped areas, you need a satellite map for a good rectification.
Luckily, you can activate a Google Maps satellite layer with a simple hack. Drag the following bookmark into your browser bar, and when you’re warping your map, press the bookmarklet. Under the blue ‘plus’ menu to the top right, you’ll see a new layer appear as an option: Google Maps. Click it, and you’ll be able to see google satellite imagery to rectify your map.
Click the above link, and you’ll see a page with just one link on it. Drag that link into your bookmarks bar or right-click it and save it to your bookmarks bar. Clicking that bookmark will enable the Google satellite layer in Map Warper.
Read a blog post about our initial experiments with Balloon Aerial Photography and Map Warper here: Balloon Mapping on Unterbahn