Showing posts with label LED. Show all posts
Showing posts with label LED. Show all posts

Friday, July 04, 2008

Ir Rays


A few posts before I mentioned our amazement at the strength and penetration of the infrared LED's that we are using as the beacon for our performance. I just took a screen grab of what the webcam was recording as proof that I was not seeing visions. You can clearly see the veins on the hand. I really like the shot. It reminds me of the photograms of László Moholy-Nagy

"The reality of our century is technology: the invention, construction and maintenance of machines. To be a user of machines is to be of the spirit of this century. Machines have replaced the transcendental spiritualism of past eras."
--László Moholy-Nagy

Saturday, June 28, 2008

Out of Sight

A few more days and we will be driving up the east coast to NY. I hate to think of all the gas we will burn, but I am sure it will be less than taking a plane, no to mention the cost. Nowadays it is impossible (and this is good) to do anything without minding the consequences in the bigger picture of life as we know it. I feel that finally a swell of inconformity is rising against the many tyrants that rule our world, including our inner one.

Back to business. The weight of the eyes proved too much for the tiny springs, so I decided to encase the spring inside a sturdier one and on top of that I put a couple of coats of latex to hold it together and still be flexible. That proved an overkill. The eyes became too stiff and did not respond to the movement as expected. So I carved them from an ultralight foam, and gave the a few coats of liquid gesso. After sanding them they had just the right look and weight to be supported by the tiny springs.

On the left the amputated wooden eye vs. the light foam eyeballs shown at the end of the spring. The toothpick became the optic nerve and it is passively string-controlled for the basic position and orientation of the eyes. They work beautifully and add a lot of expressiveness. The strings are connected to the end of the neck, so that when the Creator bows its head or kneels, the eyes "relax", and when he stands up they perk up very nicely. As everything puppetry and theatrical, their exaggerated irritation is understandable, given the great effort to see and make sense of an utterly absurd world.

The focal point of the entire universe of the Creator is ultimately its creature. Regardless of the external appearance, which only a parent would love, the important thing is that which radiates from it and communicates its presence. This electronic soul is extremely simple yet fascinating. We started creating the tracking beacon using standard IR (infrared) LED's. We were having problems achieving the necessary brightness to be detected at a long distance. On top of that, since the creature moves around the stage wildly shaking every part of its body and sometimes lowering its head it was important that the beacon be visible in all circumstances. Adding the half-pong ball (sanded to paper thin) helped the angle spread of the light but we thought that it would cut the light considerably.

And indeed our first tests confirmed that. So we bought the super-wide angle IR LED's in the hope of solving the angle problem and still retaining the strength of the light. (see the previous post on that here)


Now comes the ignoramus part, which if we had done a little more research would have been avoided. All the webcams we tested have an internal filter that blocks IR, not exactly sure why (have not had a minute to explore that). So we proceeded to dismantle the lenses to remove such filters. (unfortunately we were so engrossed in doing so that I forgot to take pictures of the process!) This tested every sense and the steadiness of our hands, not to mention memorizing the order and orientation of every microlens. In fact, in the case of our wide-angle camera shown previously, after removing the IR blocker, we had to rearrange all 9 lenses and spacers in any imaginable way until we hit on the right one. Philip which has much better eyesight ended doing the final assemblies and it was nerve wracking to watch, almost like a brain surgeon removing a micro tumor.

The original beacon, which we will use as a backup since it is even brighter because it has more LED's to begin with.

Well, then we were up for a big surprise, in fact we are still amazed at what we saw. First of all, the camera with the exposed film in place (to filter most of the visible light) not only saw the light, but it was as bright as pointing the camera to the sun! At this point we realized that both the standard LED's as well as the wide-angle ones work practically the same. You could turn the beacon even 180 degrees (in other words showing the back) and the camera would still see it very brightly.

But then we were in shock. By holding the IR device in our hand we observe something amazing. We could not only see the light going through our hand, we could see every vein as well! very much like x-rays, except we could not see the bones. Again, the surprise was such that I forgot to take pictures of this, but tomorrow I will. We even put the thing inside our mouth, but the cheeks were way to thin for the strength of the light. This immediately brought questions about the safety of this light which we had not considered.

So I have been reading papers and reports by organizations such as The International Commission on Non-Ionizing Radiation Protection, but have found little indication of danger at that level. However, although LED's are classified as IR-C are supposed to have a minimal penetration of the skin, while IR-A which is labeled as hazardous is said to penetrate the skin only a few millimeters. So something is odd here. More food for thought.

Saturday, June 14, 2008

The Cyclopean Eye

The tiniest springs I could find in my "this could be useful" parts bin

The eyes are an important means of expression of the "soul" of a person, animal or character. The only external organ that connects directly to the brain through the shortest possible path.
The eyes of the creator move nervously as he scans its surroundings. Its world. They are animated by a simple spring mechanism that responds to the smallest movement. I did not know it was going to be so challenging to do this, except that, as we have found out, scale matters. And the smaller the scale the more critical the elements become.

The springs proved to be too weak to support the weight of the eye,
so I added a coat of latex to strengthen and stiffen it a bit,
but it proved to be a little too much so I ended up burning the latex away.
The residue that it left iwas just the right amount.

Lorena irritating the eyes

Of course the real "eye" of the Creator is up in the sky, or rather the ceiling in this case. This cyclopean eye that sees and controls everything is more and more a pervasi and accepted fact of life, in our streets, our buildings and even our homes, not to mention the "real" and inaccessible eye in the sky who observes and analyzes our every move, both as a species as well as individually when the need arises.

A very wide angle camera (76 degrees) was the choice after a good deal of research, and it proved to be the right one. I like that it is flat and although the base actually sucks if you are going to use it on a desk or a monitor it is perfect to tape to the roof and adjust the angle precisely. I needed a wide angle because the ceiling at the venue is not very tall and the camera must cover at least a 10x10 mt performing area, the world of the Creator, its Tartarus.

HP 2 megapixel camera, 76 degrees FOV

Related to the eyes or rather vision system is the light. Not the infrared light that the camera detects and processes but the actual "stage lighting". For quite a while I thought I was going to have to finagle a small lighting system form the theatre department at my university but since that was not very promising I started looking around for solutions.

I must say I am very happy with the outcome. I bought some inexpensive 12 LED flashlights at the local supermarket and hacked them (literally) so as to keep only the front portion. The advantage, in this case, of a cheap Chinese product is that it was very easy to solder to it, unlike more sophisticated models. The beam is extremely bright and is easily controlled by the microcontroller. So I have 4 "spots" with different color lights (a color filter on the LED's) to dramatize the scene and automatically create different moods according to the moment.

I got the plastic flexible contraption to where I attached the light base from one of my many "possible useful things" boxes. I wish I knew what it is or where it came from, maybe someone does becasue it is extremely practical for this and I am sure, other, applications. I suspect that it might belong to some fluid dispensing system.

The following are the very first tests with my new lighting system. I love it! absolute and precise positional and intensity control.