light

Light Responsive Animation

Animation Still

Click here to see an extract of the animation: animation(s)

 

Before I came to the Metal Lab I had been working to create an animation that would connect light to duration and time and explore an idea of exposure in digital format.  The lab offerred a great site to try out the apparatus. The were some nice windows with a view out to the amazing estuarine vista, there was a buzz of activity in the space in front of the window so the opportunity was there.

The apparatus itself would monitor light levels coming through the window using a light dependant resistor. This went through  a micro-controller, into the software and would in turn control  the brightness and contrast of an image captured through a video camera and then the frequency at which the images were captured.  When the images were captured they were uploaded to a server where they could be captured and compiled into a stop-frame animation.

 

Here is the patch for people who like these things:

Screen shot of the Max patch I created

 

 

The apparatus created a space for me to have many conversations and reflect on the critical environment of the labs and begin to take apart and address the individual elements of the work and how they interact with this idea of software culture.

My conclusion is something like…. why am I trying to create a device to capture an image in response to light when I have a camera already?

 

 

Leave a comment

Prototype: Sensing the Sun through Vibration

I finished building the first prototype: a device that allows me to navigate the “lightscape” while feeling with my skin where the brightest direction is. This simple media system allows me to be affected by the Sun (and by light in general) through a different pathway. The idea is to experiment with the possibility of enabling a new sense, opening new channels of transmission between bodies.

(more…)

Leave a comment

Sun Gazing and GSR

I just went and did a quick experiment. I went out and stared at the sun for half an hour until it set behind the horizon. I was recording my galvanic skin response and drawing a graph with processing.

The measurements are very scattered, picking up and down… There is a quieter pattern in the middle, when I was on the phone, and it goes disperse again towards the end when I go back to the staring. Then came in a took some more readings. Pattern is much more regular.

It is impossible and definitely not my intention to make assumptions regarding the meaning of these. A human body is a very complex system and its oscillations are not direct effects of clear causes but rather aggregations of hundreds of quasi-causes. Yet how cool would it be to see our interactions with other bodies expressing at the level of bodily potentials, leaving traces in the form of microchanges.

Leave a comment

Measuring Light Wavelength

TEST: How can we sense light on a particular range of the visible spectrum?
Certainly one of the most accurate sensors for such a thing is the human eye. Equipped with highly refined photosensitive cells the eye is capable of discerning between frequencies which are just a few nanometers apart. That’s why we say we have colour vision.

One of the things I am interested in though is in being able to detect the presence of blue light in an environment. In the last years a lot of work has been put into finding the photoreceptors in the retina that mediate non-visual responses to light. Regulation of circadian rhythms, mood alteration, concentration capacity, all fall under the label of “non-visual responses to light”. It seems like this could be an interesting entry point for our process of experimentation.

The cells that are held responsible for such a task are Intrinsically Photosensitive Retinal Ganglion Cells and the photoreceptor with which they carry that task is Melanopsin. Apparently Melanopsin is sensitive to a light frequency of approximetely 480 nanometers. 480nm correspond to light in the blue range of the visible spectrum as shown in the diagram below.

Visible Spectrum

If these cells can be responsible for such a broad range of “responses” they are probably a good starting point to look into new modes of communication with the sun.

What I am trying to do is to use an LDR to sense blue light. But LDR have a spectral sensitivity very similar to the human eye (since they are build to respond to “visible light”). This means they are more sensitive to frequencies in the middle range of the visible spectrum and less sensitive towards the fringes of it.

All this requires some calculation and experimentation. So the first thing I did was to set up an LDR inside a box and light up a superbright led in front of it. I did this with a blue, green, red and yellow LEDs. Then I repeated the experiment with a blue filter covering the LDR and wrote down the measurements again. The results are:

BLUE LED WITHOUT FILTER: 400 ———— WITH FILTER: 151/180
GREEN LED WITHOUT FILTER: 720 ———— WITH FILTER: 15/20
YELLOW LED WITHOUT FILTER: 710 ———— WITH FILTER: 5
RED LED WITHOUT FILTER: 720/780 ———— WITH FILTER: 5/6

So, blue light gives us lower values from the start (which makes sense if we take into account the LDR’s spectrum sensitivity. And also blue light is the one that is decreased in a smaller percentage when passed through a blue filter.

Percentage of light intensity reduction with blue filter depending on colour light:
Blue light was reduced in: 62.5% – 55%
Green light: 98%
Red light: 91% – 99%
Yellow light: 99%

So clearly the light that was less reduced through the blue filter is blue light as we could expect. Now the second thing we tried is to set up two LDRs and read their values. They were both giving similar values (although never exact). See values below.

Then we covered one of them with the blue filter and tried moving it around different sources of light. This is the setup:

Circuits of LDRs with and without filters

I plugged it into processing to be able to quickly analyse the result as I was moving around the room with my computer and the arduino plugged in. The red line in the graph corresponds to the LDR without filter and the blue light corresponds to the LDR with the blue filter (and therefore more sensitive to blue light). What the graph shows is that the differences between indoors and outdoors are more extreme for the blue light sensor.

Leave a comment