Time-based mappings of wireless networks in urban environments
Ali Sant's Tracemap.net maps the digital signals that overlay urban landscapes. Holding wirelessly-enabled PDAs, people walking around a city move through overlapping wireless networks, both public and private. Stamen's visualizations reveal a different kind of space, by measuring and displaying the relative strength and density of these networks over time.
As a participant walks through the city, wireless networks are sensed by the PDA. Each time a new network is encountered, a new vertical bar is drawn. As each new network is encountered, its marker moves along the color spectrum. The first network is always red and on the left hand side, the last one is always purple and on the right side, and networks along the way get new colors as they come within range. The height of each bar represents the combined strength of the wireless networks currently in range.
In the image above, the walker quickly moves out of range of the first (red) network encountered on the walk, and into a new set of orange, yellow and green networks. In the image below, by contrast, the first (red) network remains within sensing distance all the way through the walk, while yellow, orange, green and blue networks all come and go. Interestingly, the yellow networks encountered early in the walk fade out of sensing range midway through and come back later, possibly indicating that the walker looped back around to within range of networks that had been sensed earlier in the walk.
The images below work in the same way, but with the addition of an extra variable: privacy settings. Open networks are above the center white line, whereas closed (private) networks are indicated darker and in the bottom half of each diagram.
Shawn Allen built these mappings in 2006.