"erasing" real shapes with a digital projection?

    Mar 05 2012 | 12:30 am
    Hi there, i have this idea of "erasing" some basic shapes with projection. For example a red square drawn on a white wall. Which color should be projected on the square to make it disappear? Somebody there knows psychology of color perception of color addition? i guess real colors don't add the same way as digital projected ones, so how to calculate this?

    • Mar 05 2012 | 12:42 am
      I'm guessing you'll have to deal a LOT with color calibration - the camera and your project will have to be very calibrated to each other for it to work at all.
      And I would guess that if you did manage to find a square that was exactly red, and only red, you could spit our blue and green. But that's probably wrong - partially because you'll never find a physical object that ONLY reflects red wavelengths, but you'll never find a projector that has the color range and depth to null it out.
      Plus, a red object won't reflect Blue and Yellow from the projector very well (because, well... it's red. that's how color works).
      Anyway, I think you might be able to get sorta close, but never to the point of making an object 'disappear.' And if your object isn't on a white wall, you not only have to be able to null out the object, but replace it with information that fits the space. Seems like a pretty big undertaking!
      Let me know how it goes!