Slit-Scan Photography and Information Display

Exploring the relationship between the digital and physical has become a primary theme of my time at ITP. The digitization of our identities, environments, and selves is a strong force that we must either work with or against on a regular basis. Conversely, we still absorb experiences through our primary five senses, so machines and devices whose purpose is to physicalize still have great importance in our world. Speakers turn electric signals into sounds perceivable by our ears, screens turn data and interfaces into light that is absorbable by our eyes, and 3D printers turn digital models into physical objects.

As a means of exploring this relationship, I’ve proposed a drawing machine that provides a measure of this physicalizing capability. Screens now dominate our visual landscape through our constant use of phones, TV’s, computer monitors and even digital billboards. They provide the capacity to display two dimensions of information, x and y, while constantly refreshing (often 60 times per second) over time, t. Is it possible to create an alternative way of physicalizing information instead?

How might it be possible to create a “screen” that is physically drawn instead of displayed using light while also being refreshed continuously?

Screens, while continuing to progress in terms of resolution and even three-dimensionality, are still conventionally two dimensions with time as an additional dimension. A piece of paper is limited to two dimensions no matter what. If we allocate the x dimensions to time in order to preserve our ability to constantly refresh, we are limited to using the y dimension for information. Some examples of physicalizing data in this matter are electrocardiograms used to monitor heart rate, polygraphs also used measure biological indicators related to lying, and seismographs used to measure tremors and earthquakes.

If we wanted to feed information collected from a camera to our drawing device, we could collapse the x dimension and time and can create a kind of seismograph of the movements along one vertical line of information or in other words a conventional slit-scan camera.

What’s a slit-scan camera?

Slit-scan cameras have been used to primarily to record the order in which contestants pass through a finish line in a race. It is a perfect example of rearranging the priorities of information that is being displayed in order to produce a more accurate depiction of information.

This is an image taken by a conventional camera capturing Usain Bolt crossing the finish line at the 2012 Olympics. It has captured one moment and shows the areas in front of and behind the finish line. It fails to show what has happened before or after that moment in time.
This is a slit-scan image of the finish line showing the moment that Usain Bolt crossed it as well as when each of the other contestants did as well. It fails to show the areas in front of and behind the finish line.

The two images above provide a comparison of the two photography techniques and how they offer different kinds of information. We can see in the slit-scan image not only who won the race, but also what order the other runners passed the finish line. We can even tell which body parts passed in what order. We can see that Usain Bolt, despite his leaning posture, actually stepped on the finish line with his toe passing it first, his head second, and his knee third, followed by the rest of his body.

The Drawing Machine

Using the visual language of an electrocardiogram and the photography technique of a slit-scan camera, I propose a drawing machine that is fed by a live feed from a camera that draws in real time what it sees. A continuous roll of paper will be fed into it while a series of pens will draw on it without breaking the stream of data. The vertical resolution will be determined/limited by the number of pens while the temporal resolution will be determined by the refresh rate of the computer/device. Darkness will be depicted as wider swings of each pen, while straighter lines will show lighter areas. Shown below is a preliminary rendering of the device.

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