3d street painting
- Thread starter PatrickL
- Start date
PatrickL said:
impressive
Bouncing Zabaglione Bros.
Legend
pax said:Awesome... I wonder if it looks 3d from more than one angle tho... Damn those talented French!
Must be from just the one angle - it's a perspective trick. They are darn clever though...
Bouncing Zabaglione Bros.
Legend
pcchen said:
No, it works in real life too. Although you do see it as a plane and binocular vision confirms it, the processing that goes on in your brain (ie, the actual perception) convinces you that you are looking at something that is three-dimensional. Your perception recongnises the pattern and your brain thinks it's 3D, even though your eyes are just seeing a plane. Basically there is a lot more to "perceiving" something than just the light coming in though your eyes - there's loads of processing between "seeing" and perceiving". For instance the image on the back of your eye has to be flipped upside down, combined with the image of the other eye, bits filled in they your eyes are no longer registering, and then matched to what you know about what you are looking at.
There's been some interesting tests on blind people that have regained their sight through modern surgery tehniques, and they don't experience this sort of thing in the same way. Because they never had sight, their visual processing doesn't instantly make assumptions about the shape of things based on the light that comes into your eyes in the same way as a normal sighted person does.
Bouncing Zabaglione Bros.
Legend
pcchen said:
Sure a photo is not 3D, but as I said above, what your brain percieves is not that same thing as light coming into your eyes.
How do you think optical illusions work? Your eyes see something, but your brain decides it is something else. It's not your eyes that are misled, it's your brain's processing of what is coming in through your eyes that gets the answer wrong.
Just go have a look around your local science museum - I'm sure they will have lots of 2D and 3D optical illusions that illustrate my point. Or look at those adverts on the sports field that are on the ground, but are made to look like they are standing up for the TV cameras. Or those signs painted on the roads that elongate the words to make them look like they are standing up, and so are more readable. Or get some graphics software out and play with perspective transforms.
When you render a scene, the view point (camera position) will be built in to the image. And if you display the image on a screen or a printout, that view point will still be there. It's one distinct point in front of the image.
We humans are very used to watching perspective projected images, but we usually don't look at them from the correct view point. So even if we're quite capable to see the perspective, it still looks quite flat.
But something interesting happens if you move your eye to the correct view point. The scene will get much more realistic, because the perspective is right. One problem is of course that there's only one view point and you've got two eyes. So you'll need to close one eye. (Or make a stereographic image that actually have one view point for each eye.)
If you want to try it with a game, then most of them have the view point located straight out from the center of the screen, with a 90º horizontal fov. This means that you have to move your eye to ~0.7x screen width from the screen. That's so close that you might have a hard time focusing even if you have a 21" monitor. But you'll probably still see that the image gets a bit extra "life". (With a big backprojected monitor it could look realy nice.)
This street paintings use the same effect. If you're viewing it from the right spot it can be very convincing, just because the perspective is better than in most images you view. The large size of the images means that the relative error from looking with both eyes is much smaller than on a computer monitor. Move away from that right spot though, and the effect is ruined.
Back when I was living in a dorm, I made a similar thing. I covered one wall with paper. Then drew a painting on it so that if you stood on the walkway outside and looked into my window, it looked like someone had thrashed the wall into the next room.
We humans are very used to watching perspective projected images, but we usually don't look at them from the correct view point. So even if we're quite capable to see the perspective, it still looks quite flat.
But something interesting happens if you move your eye to the correct view point. The scene will get much more realistic, because the perspective is right. One problem is of course that there's only one view point and you've got two eyes. So you'll need to close one eye. (Or make a stereographic image that actually have one view point for each eye.)
If you want to try it with a game, then most of them have the view point located straight out from the center of the screen, with a 90º horizontal fov. This means that you have to move your eye to ~0.7x screen width from the screen. That's so close that you might have a hard time focusing even if you have a 21" monitor. But you'll probably still see that the image gets a bit extra "life". (With a big backprojected monitor it could look realy nice.
)This street paintings use the same effect. If you're viewing it from the right spot it can be very convincing, just because the perspective is better than in most images you view. The large size of the images means that the relative error from looking with both eyes is much smaller than on a computer monitor. Move away from that right spot though, and the effect is ruined.
Back when I was living in a dorm, I made a similar thing. I covered one wall with paper. Then drew a painting on it so that if you stood on the walkway outside and looked into my window, it looked like someone had thrashed the wall into the next room.
Bouncing Zabaglione Bros. said:
The key point here is, when you are using both of your eyes.
For example, there is an example above which contains a uprising hand. Do you really think, when you are using both of your eyes, you will see a uprising hand? Maybe, if you are not paying attention, having too much caffeine (or other drugs), or drunk. Otherwise, you are likely to see a flat hand. That's because your brain know it's flat, by processing the two different images from your two eyes.
To my experience, the stereovision comes from two eyes is much stronger than most (if not all) types of optical illusion, when you are close to the object (several meters or closer). That's why people spend so much money trying to put different images to each eye, to create realistic stereovision. For far away objects, stereovision mainly comes from object size and fog. So if you have a very big poster designed to be viewed from a long distance (several hundered meters), you can make it pretty "3D", if the viewer looks it from a correct view point.
Otherwise, as Basic said, to fool one to think it's a 3D, you need to close one eye.
Bouncing Zabaglione Bros.
Legend
pcchen said:Otherwise, as Basic said, to fool one to think it's a 3D, you need to close one eye.
If it doesn't work in person, why do you think all these street artists are painting on the pavement where people are going to see it in person?
You severely underestimate the effect the brain has on what you perceive. You see something that looks like a hole in the ground, and your brain decides it *is* a hole in the ground, and that is what you "see". Sure if you move out of position so that the perspective trick no longer works, your brain won't be fooled.
Like I said, go to your local science museum, and you'll find loads of this stuff there to look at yourself.
Bouncing Zabaglione Bros. said:If it doesn't work in person, why do you think all these street artists are painting on the pavement where people are going to see it in person?
I have to say that I never see them in person. However, my experience (including seeing specially designed photos put on the ground) tell me that it may be surprising at first, but most people will realize it instantly.
No, I think you underestimate the power of the weight brain gives to two-eye stereovision.
Perhaps I didn't explain it clear enough. Actually, brain learned how to interpret 3D from a projected plane since we are just babies. This does not come natually, and have to be "learned". This brings the ability to understand the projection in pictures and photos, and estimates size and distance of far away objects. On the other hand, the ability to estimate distances from "binocular vision," is likely natural (brain does not "learn" this). This is probably because predators need to estimate short distances accurately. On the other hand, far away objects either are not worth pursuing, or are not possible threats.
Anyway, I'm not saying they are not impressive artworks. Actually they may work for many at first glance, but many people will realize it's flat in their second look, if they have good stereo vision. When they learned that it's flat, even goes back to the correct viewpoint will change nothing: it won't look like 3D anymore.
streetpainter
Newcomer
Bouncing Zabaglione Bros. said:If it doesn't work in person, why do you think all these street artists are painting on the pavement where people are going to see it in person?
You severely underestimate the effect the brain has on what you perceive. You see something that looks like a hole in the ground, and your brain decides it *is* a hole in the ground, and that is what you "see". Sure if you move out of position so that the perspective trick no longer works, your brain won't be fooled.
Like I said, go to your local science museum, and you'll find loads of this stuff there to look at yourself.
hi all...
)you are right. for most of untrained persons 3d-pictures are difficult to recognize. that's because they see it is painted with chalk and plane. for that reason we use a lens which is placed on a tripod at the right viewing position. the spectator looks through the lens with one eye closed. otherwise it is hard to tell people how to watch the picture.
http://www.european-street-painting.com/street%20art%20johnnie%20walker%20taipei.htm
have a look at the photos from beside. they look distorted - following the laws of perspective. i like these effect and confusing people this way...;o)
ciao, edgar
I love these. Check out the swimming pool one from a different angle. Wow.
http://www.rense.com/general67/street.htm
http://www.rense.com/general67/street.htm
Similar threads
- Poll