Wednesday, June 9, 2010


Aluminium reflects light. Especially when it is IR.

IR cameras go crazy. They detect markers everywhere. "I don't know what all to track!", they seem to scream. A4 sheets of white paper help somewhat. Not much though. A piece of paper, torn from your notebook, stuck on the offending portion of aluminium does marginally better. It works not because it doesn't reflect, but because it "reflects" it in some other direction. Thank those imperfect sticky tapes and bad planning that prevent the paper from forming a flat surface.

"Aha!", you say. "Black is black because it doesn't reflect. Hence! Therefore! Cover with black." Sadly, a robotics lab is not the art department. Paper, is white, and meant to be stuff on which research descriptions and equations ought to be printed. The spare black trash bag is used to test the hypothesis. It's glossy. It reflects. Less. But not zero reflection.

Next brain wave - "glossy" was the problem. See discarded packaging boxes lying around. Pick up one box, go ninja on them. (Ninjas are Japanese. Do they practice origami when dealing with paper? If so, they are in trouble. Origami involves only folding paper, no tearing. Hence, to be safe --->) Go Samurai on them. (Shit! They are Japanese too. But at least we know they carry swords. OK, back to science.) Cover reflecty surfaces with 'packaging boxes paper'. Success!

Moral learnt: Visible color black means visible light is not reflected. Also, since it is infrared light, you must revise your entire notion of reflection of light. Remember the goddamn physics you learnt, fool.

Many days later, figuring out what to replace your crude packaging paper with, to make it more professional and tidy, gives you headaches. Black cloth seems to be a good bet. Dommage! C'est marche pas.  :(
If cloth won't work, what will? In the back of the mind, here is what goes on: The paper was sorta rough and thick. The cloth was sorta silky smooth and thin. Hmm, a pattern, Watson! Probably thick/ big sheet of chart paper will work.

Notice a shadow on the screen as seen in one of the cameras. A piece of foam is causing it. Aha! Is it causing a shadow (i.e blocking something), or is it genuinely absorbing the IR light? Move it over to cover that aluminium portion right next to IR emittors, and see how it performs when it receives a full blast of infrared love. It's. Still. Black! ZING! A clothed version of Eureka Eureka!

Research. It's not always about math equations and cool code.


  1. Last line ek number ahe !!! Wah mandar wah !!!

  2. Dude, whenever you get the time, please send me a long, detailed email about exactly what you are doing in France. I really, really, really want to read. And then maybe make a film about it. (I'm very obviously joking in the last sentence. :P But please do send me that email.)