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Map Warper

Mapwarper is an open source map geo-rectification, warping and georeferencing application. It enables a user to upload an image, a scanned map or aerial photo for example, and by placing control points on a reference map and the image, to warp it, to stretch it to fit.

Map Warper screenshot of main interface

The application can be seen in use at for public use and in library setting at

The application is a web based crowdsourced geospatial project that enables people and organisations to collaboratively publish images of maps online and digitize and extract vector information from them.

Users rectify, warp or stretch images of historical maps with a reference basemap, assigning locations on image and map that line up with each other. Often these historical maps were in big paper books, and so for the first time they can be stitched together and shown as a whole, in digital format.

Users can crop around the maps, and join them together into mosaics (previously called layers).

By georeferencing the images, they can be warped or georectified to match the locations in space, and used in GIS software and other services. One such use of these warped maps is an application that that helps people digitize, that is, trace over the maps to extract information from them. For example, buildings in 18th Century Manhattan, details changing land use, building type etc. This application is called the Digitizer.

The application runs as a Ruby on Rails application using a number of open source geospatial libraries and technologies, including PostGIS, Mapserver, Geoserver, and GDAL tools.

The resulting maps can be exported as a PNG, GeoTIFF, WMS, Tiles, and KML for use in many different applications.

Groups of maps can be made into "mosaics" that will stictch together the composite map images.


  • Upload image by file or by URL
  • Find and search maps by geography
  • Adding control points to maps side by side
  • Crop maps
  • User commenting on maps
  • Align maps from similar
  • Create mosaics from groups of maps
  • Login via Github / Twitter / OpenStreetMap / Wikimedia Commons
  • OR signup with email and password
  • Export as GeoTiff, PNG, WMS, Tile, KML etc
  • Preview in Google Earth and Google Maps
  • User Groups
  • Map Favourites
  • Social media sharing
  • Bibliographic metatadata creation and export support
  • Multiple georectfication options
  • Control point from files import
  • API
  • Admin tools include
    • User statistics
    • Activity monitoring
    • User administration, disabling
    • Roles management (editor, developer, admin etc)
    • Batch Imports

Note on code and branches

Unmaintained branches exist for older systems and setups

  • Rails 2.3 and Ruby 1.9.1 - See the ruby1.9.1 branch
  • Rails 2.3 and Ruby 1.8.4 - See the rails2 branch

Ruby & Rails

  • Rails 4.1.x
  • Ruby 1.9


  • Postgresql 8.4 (or 9.1)
  • Postgis 1.5 (may work with 2.0)

Installation Dependencies

Check out the Vagrant section lower down in the readme if you want to get started quickly.

on Ubuntu 14.04 LTS

apt-get install -y ruby ruby-dev postgresql-9.3-postgis-2.1 postgresql-server-dev-all postgresql-contrib build-essential git-core libxml2-dev libxslt-dev imagemagick libmapserver1 gdal-bin libgdal-dev ruby-mapscript nodejs

Due to a bug with the gdal gem, you may need to disable a few flags from your ruby rbconfig.rb see zhm/gdal-ruby#4 for more information

Then install the gem files using bundler

bundle install


Create and configure the following files

  • config/secrets.yml
  • config/database.yml
  • config/application.yml

In addition have a look in config/initializers/application_config.rb for some other paths and variables, and config/initializers/devise.rb for devise and omniauth

Database creation

Create a postgis database

psql mapwarper_dev -c "create extension postgis;"

Database initialization

Creating a new user

user =
user.login = "super" = ""
user.password = "your_password"
user.password_confirmation = "your_password"

role = Role.find_by_name('super user')
user = User.find_by_login('super')

permission  =
permission.role = role
permission.user = user

role = Role.find_by_name('administrator')
permission =
permission.role = role
permission.user = user


Via Vagrant - There is a vagrantfile you can use this uses a provision script in lib/vagrant. Type

vagrant up

to get and install the virtual machine - this will also install the libraries and depencies and ruby gems for mapwarper into the virtual machine. See the file in lib/vagrant/ for more details about this process

After that runs, type vagrant ssh to login and then you can

cd /vagrant
rails c

Create a user in the console, as shown above and then exit

rails s

to start the server, running on port 3000

Deployment instructions

The system can use capistrano for deployment


See for API details


Wikimedia Commons map georectifier and warper. See wikimaps_new branch.






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