Like walking, but with paper
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Paperwalking is the codebase behind
Copyright (C) 2009-2010, Michal Migurski <>

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

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.

1. Site

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 "webmaster" account I use to host Walking Papers.

2. Decoder

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: