“The complex technologies the networked city relies upon to produce its effects remain distressingly opaque, even to those exposed to them on a daily basis.” – Adam Greenfield (2009)

Immaterials: light painting WiFi film by Timo Arnall, Jørn Knutsen and Einar Sneve Martinussen.

This project explores the invisible terrain of WiFi networks in urban spaces by light painting signal strength in long-exposure photographs. A four-metre tall measuring rod with 80 points of light reveals cross-sections through WiFi networks using a photographic technique called light-painting.

This builds on a technique that was invented for the 2009 film ‘Immaterials: the Ghost in the Field’ which probed the edges of the invisible fields that surround RFID readers and tags in the world. It also began a series of investigations into what Matt Jones richly summarised as ‘Immaterials’.

While we were mapping out tiny RFID fields, we wondered what it would be like to apply the light painting process to larger-scale fields of Bluetooth, WiFi, GSM and 3G. What if we built huge light painting apparatus that could map out architectural and city-scale networks in the places and spaces they inhabited? We’re still very interested in understanding radio and wireless networks as one of the substrates essential to contemporary design practice.

We built the WiFi measuring rod, a 4-metre tall probe containing 80 lights that respond to the Received Signal Strength (RSSI) of a particular WiFi network. When we walk through architectural, urban spaces with this probe, while taking long-exposure photographs, we visualise the cross-sections, or strata, of WiFi signal strength, situated within photographic urban scenes. The cross-sections are an abstraction of WiFi signal strength, a line graph of RSSI across physical space. Although it can be used to determine actual signal strength at a given point, it is much more interesting as a way of seeing the overall pattern, the relative peaks and the troughs situated in the surrounding physical space.

After a week of walking through urban spaces holding and photographing this instrument, we have a much better sense of the qualities of WiFi in urban spaces, its random crackles, bright and dim spots, its reaction to the massing of buildings, and its broad reach through open areas. The resulting images show some of these qualities, and light painting is a brilliant medium for situating visualisations and data into physical world locations and situations.

Lots more visualisations and ‘making of’ pictures.

Einar writes more about this in an upcoming article called ‘Making material of the Networked City’ in Design Innovation for the Built Environment – Research by Design and the Renovation of Practice. There is also more detail on the project at the YOUrban weblog.

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This video is about exploring the spatial qualities of RFID, visualised through an RFID probe, long exposure photography and animation. It features Timo Arnall of the Touch project and Jack Schulze of BERG.

The problem and opportunity of invisibility

RFID is still badly understood as an interactive technology. Many aspects of RFID interaction are fundamentally invisible; as users we experience two objects communicating through the ‘magic’ of radio waves. This invisibility is also key to the controversial aspects of RFID technology; once RFID antennas are hidden inside products or in environments, they can be invoked or initiated without explicit knowledge or permission. (See here for more on the invisibility of radio.)

But invisibility also offers opportunities: the lack of touch is an enormous usability and efficiency leap for many systems we interact with everyday (hence the success of Oyster, Suica and Octopus cards). But there is also the ‘magic’ of nearness one of the most compelling experiential aspects of RFID.

As designers we took this invisibility as a challenge. We needed to know more about the way that RFID technology inhabits space so that we could better understand the kinds of interactions that can be built with it and the ways it can be used effectively and playfully inside physical products.

The experiments

In order to study the readable volume around an RFID reader, we built experimental probes that would flash an LED light when they successfully read an RFID tag. The readable volume is not the same as the radio field, instead it shows the space within the field in which an RFID tag and an RFID reader will interact with each other.

One version of our probe containing a tag and LED light connected to the RFID reader that is being studied.

In a dark room, the probes were moved around the various RFID tags and readers that we wanted to study, with a camera taking long-exposure photographs of the resulting patterns of light. In this way we could build up layers by slicing through the field in different ways, creating animations that clearly reveal the spatial properties of this interaction.

These experiments were carried out in order to help us flesh out our own models of the technology, and were not intended to be scientifically accurate. So although they accurately reflect the behaviour of the technologies in the situations that we work with, there were no controlled environments or settings for generalisable technical accuracy.

Innovations ID 20

The Innovations ID 20 RFID reader has become one of the standard components in a lot of our work, it is small, robust and relatively cheap. So it has been very important for us to gain an understanding of the readable volume it produces when we embed the reader inside products such as Sniff and Skål.

Details: Innovations ID20 low-frequency EM4102 reader, 20mm circular EM4102 tag.

The resulting visualisation shows the way in which we have mapped the boundary of the readable volume, although a tag will read anywhere inside this, we have only mapped the edge for the sake of clarity. From the animation (see the video) we start to clearly see that the readable volume is made up of a strong central sphere, accompanied by a smaller lobe that surrounds the edge of the reader.

Oyster card

Mifare cards are one of the largest public applications of RFID, used in many transit systems around the world such as the Oyster and Suica cards. It has become common to have to touch in and touch out of subway stations, and many people have become accustomed to this interaction. So what does the readable volume around an Oyster card look like?

Details: Standard Mifare Oyster card, probed with a Sonmicro high-frequency reader.

With a square antenna inside the Oyster and the Sonmicro reader, we get an elongated main volume, accompanied by long skinny lobes on each edge of the card. This looks very different from the ID 20 mapping.

Orientation

The first two mappings held the reader and the tag parallel to each other, but we predicted that there would be a higher degree of complexity in the relationship if the tag and the reader moved in different orientations. The rig below was built so that we could control the angle between the reader and the tag, which moved along the surface of the table.

Details: Innovations ID20 low-frequency EM4102 reader, 50mm circular EM4102 tag.

There is clearly enormous physical complexity in this relationship, in the animation we can see the volume growing and shrinking, lobes turning into spheres, and vice-versa. But the animation gives us a very clear picture of the ‘throw’ of the reader onto a single two-dimensional plane, almost like looking at it as a torch.

Parallel and perpendicular

To show the two extremes of the relationship between orientation and the readable volume, we created two mappings, one with the tag parallel to the reader, and the other with the tag perpendicular. We mapped them using two different colours of LED: green for parallel and red for perpendicular.

Details: Innovations ID20 low-frequency EM4102 reader, 20mm circular EM4102 tag.

This image is a composite of the two mappings (see the video for animations of the two mappings separately) and it is clear that the readable volume is significantly different. When the tag is perpendicular to the reader, there is a sizeable gap in the middle of the reader where the tag will not read, creating two readable volumes side by side.

Conclusions

We have been continually challenging the ways in which RFID technology has been framed. It is incredible how often RFID is seen as a long-range ‘detector’ or how little relevant information is contained in technical data-sheets. When this information is the primary material that we are working with as designers, this is highly problematic. By doing these kind of experiments we can re-frame the technology according to our experience of it, and generate our own material knowledge.

One of the early motivations in this project was the way in which the animations really captured our tacit, embodied knowledge of the readable volume in a visual way, it was almost as if you could wave your hand through the floating green LEDs and feel them. Of course we had felt it hundreds of times in experimenting with tags and readers, but we had never seen it captured in an image, in a way that was communicable to others without having them try an interactive demonstrator. With this visual material, we can communicate about RFID in ways that we couldn’t previously.

So we hope that this work goes some way towards building better spatial and gestural models of RFID, as material for designers to build better products and to take full advantage of the various ways in which spatial proximity can be used. And with this better understanding we hope to be able to discuss and design for privacy and the ‘leakage’ of data in a more rigorous way.

Field icon

Download a PDF file of the RFID icon.

This RFID icon is based on the shape of the ‘readable volume’. Created by Timo Arnall & Jack Schulze, it is licensed for use under a Creative Commons Attribution 3.0 Unported License.

Go ahead and use it!

Credits

The project was made by Timo Arnall and Einar Sneve Martinussen from AHO and Jack Schulze from BERG. Thanks to Jørn Knutsen for help in building the rigs.

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One of the aims of the Mediamatic workshop was to experiment with ubiquitous technology for social and playful purposes. Every participant in Picnic was issued with an RFID tag that could be used by various installations around the conference venue. As a controlled setting this was a very interesting environment to experiment with RFID technology in use, and in particular to experiment with physical interactions in online social networks.

One of the participants on the first day. Photo by Anne Helmond.

The photo booth team consisted of Timo Arnall, Anne Helmond, Jorn Knutsen and Einar Sneve Martinussen. We wanted to create something that brought people together both in a physical activity and in an online social network. Initially we described it like this:

A photo booth that encourages people to take photos of themselves with others. By waving multiple tags over a touchpoint inside the booth, a photo is taken, a connection is made and pictures are added to the Picnic website.

We built the booth in three days, with many design iterations, and ended up with a large white box with a picnic-themed grassy interior that allowed up to about 10 people to have their photo taken at once.

Inside there was an RFID reader, a camera and a screen that would show what was being recorded, as well as showing a countdown for picture taking. Outside a large LCD screen showed recent and random pictures from the booth, encouraging participation. By touching your tag to a reader outside, you could see pictures of yourself.

Over the course of the three-day event the photo-booth was extremely popular and resulted in literally thousands of pictures and social connections.

Physical interactions manipulate the network

Every attendee’s RFID tag contained a link to their profile within the Picnic network site (their tags were registered and connected at the registration desk). This profile contained their name and any descriptions or tags that they had decided to include, we also had access to their contact details and payment information if we had chosen to do so. When the photo booth detected their tag, it could look them up in the Picnic social network, get their details and manipulate their profiles.

Left: Inside the booth. Right: Tags on the RFID touchpoint.

The booth attracted curious attendees, who looked at the photos playing on the outside. When they walked into the booth, and touched their tag to a ‘touchpoint’ their name would appear on a screen and a countdown would start. If others then touched their tags within this countdown they would also have their names appear in the photo. People who had their photo taken together would have a connection created between them on the Picnic network site.

On the web the Picnic network showed the pictures from the booth with the names of all the people that had been photographed together. People’s profiles included the photos of them and their connections. This was a different and new way of exploring the network and seeing the connections that had been made.

Photos from the booth were also uploaded to Flickr and tagged with the people’s first name (see for example all the photos taken of me and the tag cloud of the names and IDs of people who used the booth most).

This realtime Flickr stream appeared on the outside of the booth, where people stood around watching their recent creations, as well as seeing random photos where they or their friends appeared.

Physical proximity

With around two thousand tagged attendees this was a great opportunity to design for and study the application of social networks in physical space, and to better understand the relationship between physical interactions and the resulting effects in online spaces. The way in which the photo booth took elements of a digital network and made it manipulable in a physical context was very interesting to us.

We were interested in the details of the interactions between people, their tags and readers. In practice RFID is a relatively mundane technology, it doesn’t flash or beep or cry out for attention when it’s encased in plastic packaging. It is also very limited technically: the read-ranges are typically so low that we require people to ‘touch’ their tags to the readers.

Without explicit instruction or ‘attractor loops’ the booth worked through certain ‘gestures’ that were socially learned; people observed and then participated. The activity of ‘touching’ actually brought people—who perhaps had only recently met—into very close physical proximity. This strangely intimate setting, combined with the activity of negotiating, framing and posing for a group photo provided a space for new connections to be formed, and existing relationships to be reinforced.

The attendees also became familiar with RFID interactions over time, and once they had experienced one kind of interaction, wanted to try more. Other RFID-based installations, in particular the free-beer-machine was a very low-threshold introduction to RFID interaction with a very high-degree of motivation… This benefited us all by lowering the threshold to participation.

Playing with controversial technology

With a single touch of a tag to a reader, we could have initiated many different actions within the Picnic network site; we had access to names, profiles, contact information including addresses and phone numbers and even perhaps payment information. But we chose fairly simple events: displaying people’s first name, updating the relationships between people, and relating photos to profiles.

However given that we had access to this data, we were very surprised that nobody questioned the fact that the booth knew their name. We expected there to be questions of privacy and security and perhaps some resentment towards the ease with which the booth accessed data. It seemed that the gesture and the resulting feedback was so natural that there didn’t seem to be anything scary about a name appearing on screen, in fact people assumed that somehow the RFID tag contained the information, the network wasn’t seen as part of the interaction. This shows how readily emerging technologies can be accepted without question, and how their implications remain obscure under the surface of an engaging experience.

Low-threshold interactions with social media

Conferences are a relatively constrained setting where there is an impetus to connect with people and social networks that expand, shift and change over the course of a few days. Social networks in this controlled space have many different qualities to the ones experienced in everyday life. So installations such as the photo booth must be designed to play with the existing social fabric and activities of the conference environment.

There are many different ways in which technology can intervene in these settings, something Clay Shirky has called situated software. Whereas most online social networks require users to explicitly state relationships to each other such as ‘friend’, ‘contact’ or ‘follower’ with these physically-based interactions the connection is much more implicit and less formal.

A simple physical gesture—touching some tags together at the same time—is all it takes to create a connection. Browsing through the Picnic network after having used the booth for a few days was an entirely new experience; the network was more random and chaotic, but because it had emerged from physical, social proximity there is a richer texture to the network than one built through explicit selection. Growing an online social network through these kinds of low-threshold physical interactions seems like a interesting pattern that we might see more of in the future.

More photos from the booth and of the booth.

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Physically it’s a large enclosure that takes pictures of participants, when they touch their RFID tags to a spot inside the booth. The photos get uploaded to Flickr and connections between the people being photographed are made within the Picnic website.

The photos are displayed on the outside, where participants can touch another point and see the photos that they have taken of themselves.

It’s interesting to see the development of the photos from the late-night hacking sessions through the elation of the first trial runs to the mass usage. Now we’re at 200 photos in 3 hours.

Come and see us, we’re running until Saturday.

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