From my graphics 101 course, I recall some fundamental differences between additive (pigment) and subtractive (light) color theory that are driving me crazy.
The tower itself is noted to be painted in a gray (grey) - brown color, or a “bronze” as noted at same site (interestingly enough, it changes over the height of the tower to look the same against the sky as it does against the horizon). http://www.toureiffel.paris/en/everything-about-the-tower/themed-files/97.html
To me “Bronze” means an orange hue with a heavy level of gray and a slight sheen.
So here’s my question.
How can applying external illuminating light to reflect off of something that is gray-brown (bronze) end up making it look white? Have you ever in your life been able to take something brownish or of an orange hue, and by applying external light of any color made it appear white? I think it is impossible. A white object can be made to look any color other than black or gray by shining the correct light onto it, but as soon as a hue is added to the object then the possible reflected colors are limited and adding light cannot get it back to white.
So, either my assumption (the beams are reflective) is wrong, my understanding of the color (hue) of the tower is wrong, or my understanding of additive light is wrong… and somehow a brown object can be made to appear white by adding light.
Anyone have thoughts on how in the heck portions of the tower are made to appear white? (and…blue… which is complimentary to orange and again… cannot be created by adding any color of spotlight onto an orange object)
The paint reflects all colors, just not all equally well.
With enough light of the right color mix, you can get the reflected light to look like any shade you want.
The tower also has thousands of lights attached to the structure itself and, although I couldn’t find a cite that really explains it, they seem to be able to change the color of them.
I think that my assumption that the light is reflecting off of the tower structure is incorrect. From the images in your link, I think the lights are aimed outward and are “highlighting” the structure rather than “illuminating” it.
I cannot imagine flood-type lights that can reflect off of a brown/orange to be all of those colors.
I dunno, now that I look at it, I think they are lighting it differently. See this video. I don’t know what they’re called, but the tower is made of three “sections” and there are clearly white lights pointing up at the base of the second section to illuminate it and blue lights at the base of the third section and, as those lights fade out, more lights inside the tower pointing up to make the rest of it blue. The red base also doesn’t seem to be using red lights attached to the tower, but I assume are bathed in red light.
I guess your question still stands. I don’t know the answer, but there are black projection screens and even paint that can be painted on a wall and used as a projection screen.
Panache45 has it right. You see it as “white” even though it isn’t actually white, because the light levels around it are so low. See the classic chess board/shadow optical illusion.
My favorite example is projection screens. Take a look at a screen, and it looks white. Project an image of a chessboard on it, and you see white and black in the image. At best, the “black” that you see in the checkerboard is the exact same thing as the “white” you see when there’s nothing on the screen.
It’s similar to that stupid to-do about what color the dress was. If your brain makes different assumptions about the levels of ambient light, it sees colors differently.
It’s your understanding of how color vision works that’s wrong.
Start with the fact that color optical illusions exist. These illusions prove that color is a decision process by the brain. These illusions don’t trick your eyes, they trick your brain.
Think about the implications. In this illusion (X Illusion) the wavelength of light coming into your eyes from both X’s is exactly the same - exactly the same - yet you see them as different colors. Proof positive that there is more to color perception than “wavelengths.”
It turns out that a big part of color perception is based on the relative brightness of everything in your visual field. So to get the “brown” Eiffel tower to look “white” all you have to do flood the area you want with very bright white light and then give your eyes some red and blue for contrast an presto! There is no question that if you walked up to within a few feet of it, the “white” parts of the tower structure would look brown, as they should. It’s only the overall effect that gives you the white and part of that is because your brain knows it’s supposed to be white, regardless of the wavelengths.
The lighting on the Eiffel Tower is a lot more sophisticated than merely shining colored lights on it. I was close to the tower several years ago, on the evening of Bastille Day, when there’s a light show with fireworks. At one point the tower seemed to twist, and it appeared that it was going to fall onto us. But what we were actually seeing was an image (hologram?) of the tower superimposed onto the tower. It was the projected image, not the actual tower, that looked like it was twisting.
If they can do that, they can create the illusion of “white.”
Whatever it was, it definitely wasn’t a hologram. Holograms don’t work that way. Whenever you’re looking at any point on a holographic image, your line of sight must intersect a piece of glass. You can’t just “project” a hologram out into thin air, like R2D2 does. You could maybe do something like a window that, if you look through it, you see the Eiffel Tower twisted, but that would only work for anyone looking through that window.
Most likely, all they did was put strings of lights up in the shape of twisted girders, and then lit up those strings. Or possibly whole sheets of lights that they could control as a grid, to get the same effect or others they programmed in.
