Build a GML tag recorder, win 1200 euros

Evan Roth wants a Graffiti Markup Language tag recorder badly enough to pay 1200 euros for one.

GML Field Recorder Challenge
An easily reproducible DIY device that can unobtrusively record graffiti motion data during a graffiti writer’s normal practice in the city.

Project Description and Design Requirements: The GML Field Recorder Challenge is a DIY hardware and software solution for unobtrusively recording graffiti motion data during a graffiti writer’s normal practice in the city. The winning project will be an easy to follow instruction set that can be reproduced by graffiti writers and amateur technologists. The goal is to create a device that will document a night of graffiti bombing into an easily retrievable series of Graffiti Markup Language (.gml) files while not interfering with the normal process of writing graffiti. The solution should be easy to produce, lightweight, cheap, secure, and require little to no setup and calibration.