No, sorry, the fact that you can’t touch and feel the reflection of a carving of a three-dimensional object does not make the reflection two-dimensional. It makes it a reflection. A mirror does not make a two-dimensional copy of three-dimensional object, nor does it make a three-dimensional copy of the object. You’re still seeing the same object, and it still has three dimensions.
Hmmm.
Remember those Viewmaster things? You’d put a disk in it and look through the eyepieces and see a stereoscopic picture. The disk itself had two slightly different pictures representing the same image.
The question is, is the image 3-D? A single one of the images is not, but is the whole Viewmaster system 3-D? Or is it merely the illusion of 3-D? After all, the images and the media they are printed on are quite flat.
I am still unclear as to where “interpretation” comes into play.
Are you asking me if the mirror is two-dimensional (implying the surface of the mirror itself) or if the image the mirror is reflecting is two-dimensional? The former: Yes. The latter: No.
You’re talking about two completely different things here.
The carving: Yes. The carving itself – the score marks in the stone or wood or whathave you – is three-dimensional. It has depth. The image it depicts does not. A photograph of this carving would be two dimensional in all aspects.
The mirror image: If you reach out and touch it, you’re touching a glass surface. Of course it’s two-dimensional. (If you really want to pick nits, it has texture at the microscopic level, so a technical argument on its dimensionality could be launched on those grounds – but I’m not that picky) The image it is reflecting however – not the mirror itself, not the reflective coating on the back of the mirror’s glass, not any other aspect of the mirror as an object – is in three dimensions because you are able to perceive depth therein. Depth is the third dimension, and unless you are unable to see width or height, that makes the image, by every conceivable definition, three dimensional. I can think of no conventional wisdom nor any scientific experiment that would come to a different result.
Where are you applying “three dimensional” where it means something other than “that which has width, height and depth?”
So is anything you look at out of only one eye. But if the image provides the necessary stereoscopic imagery to each eye for the brain to be able to triangulate distance then it becomes a three dimensional image.
And I think I’m beginning to understand the concept that Peter Morris is trying to get across – that of the idea that because the source of the image is two-dimensional, and because it is technically only a copy of a three-dimensional source, it still makes the image two dimensional regardless of its stereoscopy because the objects themselves do not exist beyond the image – you can’t break open the image somehow and extract the objects within. Their lack of a physical form outside of its two-dimensional representation makes them two-dimensional. If that’s the argument, I’m still not buying. If you can perceive depth in the image you are viewing, whether in a mirror or through some other stereoscopic simulation such as Viewmasters or anaglyphs, then the image is 3D.
Except that’s my point. An image in a mirror does not have depth. It has the appearance of depth, but not actual depth.
Once againwe aren’t disputing any facts here, just arguing about the meaning of words. And I’m not claiming that your definition is wrong, I’m claiming that mine is also right.
You do agree that an image in a mirror is flat, don’t you?
Right again. When you look in a flat mirror you are not seeing the surface of the mirror, except incidentally. You are seeing the light that is reflected from the surface to your eyes and that forms an image that is just as three-dimensional and just as “real” as the light that comes to your eyes from the real object.
I believe that the argument about two-dimensionality is a meaningless quibble. The source of the image is not the surface of the mirror. The source is the light that comes from the object.
Something in two dimensions has an area. Something in three dimesnsions has volume.
A mirror image covers an area, it does not fill a space, it has no volume, therefore is two dimensional.
As a physical manifestation of that which it represents, yes, it is flat – but an image is by definition not a physical manifestation. It is a physical representation, and as a physical representation it has three dimensions. (“it” in this case being a reflection in a mirror; a photograph is also a physical representation but because it is monoscopic it cannot convey depth and is therefore two-dimensional)
While discussing lightning once, a grown man informed me that a bicyclist doesn’t have to worry about lightning. When pressed for details he explained that as long as the cyclist has his feet off the ground, he is safe. But if a foot is touching the ground, he is then grounded & in danger.
I asked, “If I’m riding along on my bike & a lightning bolt nails me on top of the head, it will do no damage?” He swears I’d be safe.
I then asked, “What if I’m walking with rubber-souled footwear?” He says then I’m grounded & in danger, because my feet are touching the footwear.
I pointed out I’m also touching the bike, but he countered that I’m not touching the part that insulates me. I asked how the insulation is any good if it doesn’t protect me if I’m touching it, yet it will protect me from a direct hit if I’m not touching it. He didn’t know. “It just does.”
This mirror thing is giving me a headache. Any chance you guys can take it to a new thread? Pretty please?
This is beginning to get philosophical and like all philosophical question will never be resolved.
We never, ever see an object. What we see is a mental image constructed by our brains out of the light that comes from the object. Everything we see is imagery whether the light comes to us immediately or is mediated by a reflective surface.
However, if someone wants to believe that the image from a mirror is flat, that’s OK. The image from the mirror is still just as three dimensional as the direct image from the real object in spite of that belief.
Again, you’re approaching this on the grounds that for something to be three-dimensional it must physically exist in all three dimensions, and this is, to you, at odds with the concept of an image that is three-dimensional because the image does not physically occupy the same volume it depicts. Or, looked at another way, you’re trying to tackle a scientific principle with a metaphysical argument.
The fact that an image in a mirror reflects appearance of depth despite the fact that it has no physical presence to give depth in the way you’re thinking does not invalidate the fact that what you are seeing is still interpreted by your brain as a three-dimensional image. You can still see depth, you can still gauge distances, you can still experience parallax and all that wonderful stuff, regardless of the existence of these things in the physical realm. The fact that the image itself occupies no volume is a moot point.
But the medium is still two-dimensional. I would say that the image gives the illusion of three-dimensionality. If you want to argue that there’s no real distinction between the image and the illusion, then that’s a different matter.
I have seen some paintings in which objects are rendered as three-dimensional through clever use of perspective, logical shadows, and color. Would you consider that 3-D? If not, then what makes it different from the image in a mirror?
Annoying as hell, ain’t it? I think the worst thing is when people ask me something, I tell them I don’t know the answer, and they don’t believe me and think I’m holding out on them. My wife does this to me all the time, but at least she’s good-natured about it. I don’t know everything, dammit. Just a little bit about a few things.
Can we put the mirror thing to rest, please? Assuming a perfect mirror (and the one in your bathroom is perfect, as far as your eyes are acute enough to tell), there is absolutely no difference as far as depth perception goes between incident light received directly and reflected light. The image you see is left/right reversed, but otherwise no different.
In the alternative, just go look in a mirror and decide for yourself.
[QUOTE=Marley23]
Fuck, some people really believe in Jesus Horses?
I can’t believe this. Is this real?
I love optics.
As has properly been observed, you can easily fall into that “squirrel problem” trap in discussing this. But common sense definitions give a bit more edge to the “mirror image as 3 dimensional item” than to “2 dimensional” item. To begin with, a lot of the discussion positing it as a 2D item seems to talk as if the mirror were a 2-dimensional recording that the eye is looking at. It isn’t a 2D recording at all, of course. The “image” isn’t there any more when neither the object nor the mirror are. Nor is the mirror image like a TV screen. When I look at a TV screen at an oblique angle, the image is still visible, but begins to distort and “look flat”. You never see that with a mirror image.
In truth, the view you get through a perfectly flat mirror is almost indistinguishable from the view you get from looking through a glass window. Yet I doubt if anyone would say that the image through a glass window is two dimensional. The wavefront of the light coming from the mirror are indistinguishable from those coming from the object (or would be, if the object was reversed left-for-right). The fact that the mirror itself is flat is irrelevant.
If you don’t like that, imagine the reflection from a pair of mirrors set at 90 degrees from each other. This gives you an image that isn’t reversed left for right. And now the “mirror” isn’t flat anymore – it’s three dimensional.
A hologram is a flat medium that will, under the appropriate circumstances, return a wavefront identical to the original object as well. Even though the hologram is flat, I wouldn’t call the image two dimensional.
And it’s not just “in the brain” that these images occur. In both the case of the mirror and the hologram I can use lenses to project that image onto a piece of paper or film or a CCD.
By contrast, the view from a viewmaster does notreproduce the original wavefront, and I can’t image it in exactly the same way as I can the reflection from a mirror or the rays from a hologram. If I view the viewmaster slide from the side, it doesnt look 3D anymore. It looks like two pictures, distorted by the angle, while the mirror and hologram images still look as if I’m looking through a window. The apparent “3D” here does take place in the mind.
So the image from a mirror or a hologram is almost indistinguishable from looking through a window, because in both cases the wavefront is pretty faithfully transmitted. The image changes with orientation, and this also guarantees a three dimensional view.
I read once that when the ancient Egyptians invaded Mesopotamia, they were astonished to see the Tigris and Euphrates, “the rivers that in flowing north flow south.” The only river the Egyptians knew was the north-flowing Nile; to them, “north” = “downstream.”
[QUOTE=scott62]
No, it was a joke.
It’s no joke that CarlyJay’s friend’s mom thought dinosaur bones were just bg horses. But the SNL reference was a gag.
Well, the image that I see and you see projected on a sheet of paper is only in the brain isn’t it? And what is in a CCD isn’t an optical image but rather a set of electrical impulses.
But, as I said several times, and you know well, they all originate in the light that comes from the object and regadles of how many times they are reflected, it’s the same light and it results in our seeing a 3-D image…
There is a tiny basis in reality for that, although it’s obviously distorted to the point of dangerous misinformation.
When a woman climaxes, the cervix dips down into the vagina and sucks up whatever fluid happens to be there into the uterus. If the orgasm is simultaneous, the chances of conception are highest. (Although it’s almost as good if the woman climaxes after the man.)
Of course, strong swimmers can still made the whole journey under their own steam, but they have a much easier time of it if they’re helped along by a nice strong shegasm or six.
Doesn’t excuse a health teacher for leading young men and women to believe that male ineptitude is an effective means of birth control, of course.