cf. city flows — Streams and Traces

cf. city flows

A three-screen installation in which thousands of animated bike-sharing trips condense into comparative portraits of New York, Berlin, and London.

Year
2015
Type
Installation
Exhibited
Streams and Traces · IEEE VISAP · The Art of Networks III · +4 more
Role
Visualization design · Code
With
Till Nagel · Marian Dörk
Tech
Processing · Unfolding Maps

cf. city flows is a comparative visualization environment of urban bike mobility: three high-resolution screens, side by side in a public exhibition space, each showing the bike-sharing system of one city — New York, Berlin, London — as thousands of animated journeys flowing through the night.

Every trip leaves a trail of light; together the trails condense into a portrait of a city defined by its transient dynamics rather than its buildings. Because the three cities run in parallel under the same visual language, visitors start comparing casually — and read the pulse of urban mobility without ever seeing a chart.

The piece moves between two modes — evocative, flowing views for ambience and staged, comparative views for analysis — a strategy we wrote up as “Staged Analysis” for IEEE VISAP. It traveled from Streams and Traces in Berlin to the IEEE VIS Arts Program in Baltimore and The Art of Networks in Boston, and was covered by The Guardian, Vox, and the Processing.org exhibition.

In a separate study I pushed the approach further and designed a set of tools for the space-time geography of flow data — early experiments visualizing origin/destination movement with edge bundling in 3D (screenshots).

Developed with Till Nagel and Marian Dörk at the Urban Complexity Lab, FH Potsdam.

A tall black wall in a white room with three screens set side by side, showing New York, Berlin and London at night from above, and a low black plinth in front with a tablet set into its top
London seen at an angle on a dark building map, threaded with thin cyan paths and short glowing white trails for the bike trips underway at 20:55, the Thames winding dark through the middle
Citywide view
Manhattan at 08:07 on Wednesday, 3 June 2015, dark except for the trips to and from the station Pershing Square North: orange and cyan paths running down the avenues
Station view
Close view of the three screens: New York in front shows six stations as pairs of trip-trail glyphs, cyan above and orange below with the station name between them, while Berlin and London recede into the dark
Small-multiple view
The tablet dashboard in three columns for New York, Berlin and London, with totals for stations, bikes and trips, morning and evening trips, a horizon chart of trips per minute, round buttons to switch views and a time slider set to 08:20
Tablet dashboard in the plinth
Isometric line drawing of a gallery corner: three framed screens on the wall with dark city maps labeled New York City, Berlin and Chicago, each with a small cyan area chart, two gray human figures standing before them, and a small box-shaped device high on the side wall
Exhibition concept drawing
A city’s bike stations as small dots on a gray street network, with a handful of calculated routes picked out in orange, cyan and green as they run in from the edges toward the center, the words »cf. city flows« in the lower right corner
Experiment with calculated routes
A 3D study on black: bike trips lifted off the street map as curves in pink, magenta, orange, yellow, green, cyan and blue, bundling into vertical strands, with the clock reading 11:35 and a time-range slider below
3D edge-bundling study
A 3D edge-bundling study at 13:35 on dark gray: the bike trips rendered as white curved surfaces, like a cluster of sails or blades rising from cyan street outlines, above a time-range slider
Trips rendered as surfaces
Two visitors seen from behind, a man with a hand to his chin and a woman with glasses and a red scarf, studying the three screens, where London’s trails glow cyan over the gray city map

Credits
Christopher Pietsch — visualization design · code · with Till Nagel · Marian Dörk
Published
Staged Analysis: From Evocative to Comparative Visualizations of Urban Mobility — Proceedings of the IEEE VIS 2016 Arts Program (VISAP'16), Baltimore, pp. 23–30
IEEE VIS 2016 and 2017 Arts Program Gallery — Leonardo 53(1): 6–24 (entry: cf. city flows), 2020
Exhibitions
Streams and Traces, Galerie erstererster, Berlin — 2015 · IEEE VISAP, Baltimore — 2016 · The Art of Networks III, Northeastern University, Boston — 2018 · Existência Numérica, Oi Futuro Flamengo, Rio de Janeiro — 2018 · Politiken des Designs, Kunstraum Potsdam — 2018 · .Futuro, Rio de Janeiro — 2019 · CityLAB Berlin — 2019
Recognition
Kantar Information is Beautiful Awards, Dataviz Project (Longlist) — 2016
Press
The Guardian: Bike share mapping creates beautiful portraits of London, NYC and Berlin (2016) · Vox: Bike-share trips become mesmerizing droplets of light in these animated maps (2016) · The Architect's Newspaper: An interactive bike share map finds beauty in the chaos of commuting (2016) · World Economic Forum: Mapping of bike-sharing data will change the way you see these cities (2016) · designboom: urban bike share mapping installation shows london, berlin + NYC in a new light (2016) · Süddeutsche Zeitung: Die bewegliche Stadt (2016) · Die bemerkenswerte Karte (DGfK): Urbane Mobilitätsmuster entdecken (2016) · Anita Graser: City flows unfolding with the other Processing (2016) · Progrss: cf. city flows: Portraits Of Cities In Flux (2016) · Cycling Weekly: German researchers turn GPS bike share data into visualisations of cities (video) (2016) · Processing.org Exhibition: cf.city flows (2016)
Link
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