Category Archives: making invisible visible

Millennium Bridge Thermal Interactive

‘A Day in the Life of the Millennium Bridge’ by Joseph Giacomin was a collaboration between myself, Joseph and Kaveh Shirdel as part of the new exhibition in Arup Phase 2 called Bridge Stories.

bridges on the move

They say:

“The works in this exhibition celebrate the last half century of bridge projects and the engineering that has made them possible. They also show how the use of film and photography has changed since the first decades of Ove Arup and Partners – founded in 1946.”

In this guest posting Joseph describes the story behind the thermal imaging.

Millennium Bridge Story

Cold blue and hot red: can thermal photography help the Millennium Bridge to reveal itself? Does enhanced perception tell us a different story from the obvious, the everyday, the one which we already know?

A thermal journey across the Millennium Bridge reveals a strange new perceptual stage in which the “things in themselves” occupy unexpected places and exhibit unexpected shapes and colours. Parts of the bridge, parts of the city and parts of the people suddenly appear strange and unexpected. The metal supports of the bridge cool in the wind while the solid masonry foundations stubbornly retain their heat. People appear as bright glowing light bulbs, centres of heat, moving over and around the bridge in their living, unmechanical, way. Interaction occurs, with people imprinting their life force on the bridge through heat transfer from direct contact. The dome of St. Paul’s cathedral glows red as its lead covering heats in the afternoon sunlight. London’s masonry and glass glow.

To thermal eyes the Millennium Bridge reveals a new version of its story. This exhibition provides many views, and thus many stories, which are told through thermal photography. Often seen as technical tools, thermal imaging cameras can also act as translators between ourselves and our physical world, expressing sensations which cannot be stated in words, and capturing photographic insights which are lost in the visual spectrum due to clutter, confusion and overwhelming detail.

Thermal photography helps to reveal a secret life of Millennium Bridge, that of heat and energy. The choreography of sun, wind, materials, physics and living creatures is revealed to thermal eyes, and the many secret stories of everyday bridge life are told from a different perspective and a different point of view. Stability and motion, man and nature, routines of everyday life, all these plots and more are acted on the thermal stage which is Millennium Bridge.

Guide to the Thermal Images

The thermal images of this exhibition all 320X240 pixel JPEG images shot using a 60 Hz thermal imaging camera which was similar in appearance to a camcorder. Since such cameras measure a property, temperature, which is not part of the visible light spectrum, pseudo-colour was used to indicate the variations in temperature. The pseudo-colour scheme adopted was bright red-orange for the hottest temperature found in the individual image while dark blue was used for the coolest. Since the pseudo-colour scheme was normalised for each image individually, the same colour can indicate different temperatures when appearing in different images. For the current exhibition, therefore, colour should be considered to provide a measure of relative temperature rather than of absolute temperature.

Thermal imaging, or, more precisely, infrared thermography, consists of measuring the infrared radiation of the electromagnetic spectrum from approximately 900 to 14,000 nanometres of wavelength. Infrared radiation is one region of the electromagnetic spectrum, other regions being for example those of the gamma rays, x-rays, ultra violet light, visible light and radio waves. Infrared radiation is emitted by all objects and the amount of emitted radiation increases with increases in the temperature of the object. The temperatures which can be measured by means of a modern thermal imaging camera are normally from approximately -50 °C to 2,000 °C.

Infrared radiation is measured using a thermal camera in much the same way that visible light is measured using a digital camera. However, while digital cameras use a Charge Coupled Device (CCD) or a Complementary Metal Oxide Semiconductor (CMOS) sensor, thermal imaging is based on the use of focal plane array (FPA) sensors which respond to the longer wavelengths of the infrared region of the electromagnetic radiation. Given the complexity of the FPA sensors, the maximum resolution which can currently be achieved is lower than that of CCD or CMOS sensors. Most thermal imagining cameras have the relatively low resolutions of 160×120 pixels or 320×240 pixels, with the most expensive current models reaching 640×512 pixels.

While the amount of thermal radiation depends greatly on the surface temperature of the object which is being measured, the surface temperature is not the only factor involved. Other factors which effect the measurement include the emissivity of the object which is being captured, the amount of radiation arriving from the surrounding environment and the atmospheric absorption between the radiating object and the thermal imaging camera. Emissivity and atmospheric absorption thus affect the measured temperatures, and if not carefully compensated at the time of each measurement can lower the accuracy of the temperature values.

Of the factors effecting the accuracy of thermal images, the biggest is the emissivity, meaning the ability of the object’s material to emit thermal radiation. Every material has an emissivity value which is in the range from 0.0 (no ability to emit thermal energy) to 1.0 (complete emission of all thermal energy). In addition, the emissivity value is not a fixed value for most materials, but is actually a continuous function of the temperature. Given the complex physics, the maximum theoretical measurement accuracy of a thermal camera is achieved only when the emissivity value of the object which is being studied is known or when the camera can be calibrated on-sight against a known reference source of thermal radiation. In the case of the images found in this exhibition, the camera was set to run using a stored internal emissivity table, thus the camera was not calibrated for each shot so as to achieve the maximum possible accuracy.

Joseph Giacomin, Oct 2010

[If you like these images, you may also be interested in his new book "Seeing the World Through 21st Century Eyes"]

An online gallery of the photos is available and once the installation is complete more photos will be uploaded to the gallery.

And finally, it’s almost 10 years old, but still fascinating to watch, a video shot during testing of the Millennium Bridge where the footfall of 2000 members of the public was being monitored against the Synchronous Lateral Excitation of the bridge.

Millennium Bridge from Duncan Wilson on Vimeo.

And one from the local news on the opening day…

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Web of Light

Last week I attended a small gathering at Philips Design to workshop ideas for a public lighting scheme in Eindhoven.

Strijp S

The most important aspect of the Web of Light workshop for me was the focus on the motivation for installing any of the multitude of technology wizardry available. The question “Why?” took us beyond the functional aspects of safety and security or the aesthetic art installations, and forced us to think about the different community perspectives that “public light” could play in creating stimulating urban environments.

The discussions through the day meandered between different ideas but the three themes we presented at the end encapsulate the major themes of: creating interventions to encourage the digital natives to interact in public spaces (a positive take on hanging around on street corners); encouraging community interaction through creating desirable shared public spaces (a midnight urban farm was proposed as a vehicle for productive light and a beacon(s) of activity); and the idea of displaying the inputs and outputs of the creative community at Strijp S (the new smoke stacks).

Looking forward to seeing how these ideas develop both in terms of creating useful applications and in the technology backbone to be delivered (66 acres of individually addressable LEDs). [Note: one route to next steps will be through a design challenge for the Hot100 at PICNIC 2010]

Strijp S

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Arup Design School

Spent a really interesting morning at one of the Arup Design Schools – thanks to Richard and Richard for the invite! Notes from the event were tweeted but i only tagged the last one, photos are on flickr and the slides are on slideshare.

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Dopplr personal annual report

Another great piece of work by Dopplr and this time it is even more personal. Just received my dopplr2008report.pdf. 50,000km traveled, away from home for 55 days and the velocity of a duck (5.73 km/h). I love the timeline that links through to the flickr images – just need to figure out how to add one in for Ambleside…

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CO2 footprint from travel – dopplr

Great addition to the already great Dopplr tool. Am just about to expend the significant part of this years carbon footprint…


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I came across a link to this location on google maps in one of their forums and it made me smile – no other reason to post it here than that.

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Wattson 105 – measuring electrical usage

Received the Wattson from DIYKyoto last week and had a quick install at home to see how it works. It has been running for 10 days and no problems so far but have not downloaded any data yet – software is to be delivered. Install was extremely simple, just clamp the current transducer (or is it a transformer?) around one of the two wires between the house electricity meter and fuse box and then turn on the wattson. Was very interesting when we first turned it on to see how many *hidden* appliances were running. Managed to get from 600 watts down to 80 watts by turning things off standby, however notice that it seems to average 700-800 watts in the evening. Max to date has been about 2500 watts when the dishwasher was on… Next step is to install it in Arup to monitor office appliance use…

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Haringey interactive heat loss map

Nice project for Haringey Council by Hot Mapping and Horton Levi. The aerial survey measured heat loss from every property by taking thermal images. The council claim this piece of work was completed for under 21k GBP. My house is shown circled below – not bad considering our poor level of insulation – but i did not live here (in 2000) and cannot be sure if, for example, any heating was on when Horton-Levi conducted the aerial thermal survey of the whole of London. More info.


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RealCosts – visualising flight CO2 costs

Plugin for firefox that allows you to see the C02 impact of your journey WHILST you search for flights using you favorite website (US focus at mo so i had to use soon to come is a version for car directions… The calculations they are using are available on the project wiki


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visualising C0 from cars

Nice example of tangibly making the invisible visible. On the balloon it says: Drive one day less and look how much carbon monoxide you’ll keep out of the air we breath. [via infoaesthetics]

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