Paperwalking is the codebase behind http://walking-papers.org. Copyright (C) 2009-2010, Michal Migurski mike@stamen.com
See INSTALL for a guide to installing Paperwalking.
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
There are two main components here.
The user-facing website is written in PHP and MySQL, and has been developed to work adequately well in a commodity shared hosting environment, such as the Pair.com "webmaster" account I use to host Walking Papers.
The ugly math bits are done in an offline process that consumes a queue of freshly-scanned images from the main site, runs them through the image-recognition algorithm, and posts back georectified image tiles for editing. You can run a bunch of these in parallel to make jobs go faster, and they should be perfectly fine on small EC2 instances or a box plugged into plain old residential DSL.
It's worth mentioning that the image recognition part of the work relies on a patented algorithm called SIFT: http://en.wikipedia.org/wiki/Scale-invariant_feature_transform