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Author Topic: The 3-D Effect  (Read 12818 times)

jing q

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The 3-D Effect
« Reply #40 on: November 12, 2007, 02:58:12 am »

The illusion of 3-dimensionality can be created without the need of creating differences in sharpness/blurring between objects of varying distances.
If you take a look at hyperrealistic paintings (I believe there was a period in the 80s where this was the rage..) and op-art (art based on optical illusions), a sense of dimensionality was created on flat surfaces through various methods (depth of field just being one of them)

regarding your points about large prints losing their shallowness, interestingly as I had mentioned before, one of the big prints I made really took on a very dimensional feel only when printed big, and I noticed the effect wasn't due to the depth of field (yes it was shallower...but not extremely), but the detailed tonalities between colours on the people's faces and clothing that created a sense of volume in each object.

I'm of the personal belief that if you have an image that is uniformly sharp (due to a small aperture perhaps) your brain can perceived dimensionality through the sense of volume of the objects.

I'm sure depth of field is one method but from what I've experienced I find that there are other issues involved too like enhanced details such as the amount of transitions between tonalities (especially with something like skin) and fine details which create a sense of objects being more "alive"

Take a look at some hyperrealistic sculptures (which are 3 dimensional in the first place...and yet they can seem more "dimensional" than reality)


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How can that be? As I mentioned before, the two most obvious clues that tell the brain it is perceiving a 3-dimensional image when in reality the image is 2-dimensional are (1) distant objects are smaller than near objects, (2) objects that are partially obscured by other objects can only be obscured by objects that are closer. Those are basic concepts we begin to learn as babies.

There is some story I recall related by Michael R, about a remote tribe of natives who had spent all their lives in dense jungle and who had never seen anything further away than a few metres. When they were led out of the jungle by some anthropologist who was studying their culture, and saw for the first time a vast open vista, a plain below the cliff's edge stretching for miles, and what appeared to be in the distance grazing cattle, these natives assumed that the cattle were ants because they were so small. It was difficult to convince them that these tiny creatures were actually huge wildebeeste, presumably because that would have introduced an entirely new concept to their hard-wired brains, namely that there existed vast areas without trees stretching for great distances.

In this sense, great (or extensive) DoF is required for a good 3-D effect. If you can't recognise to some degree those small objects that denote distance, because they are out of focus, then it's difficult to understand how one could get an impression of great 3-dimensionality.

On the other hand, as photographers, we know that those things in that 2-dimensional image that are out of focus are out of focus precisely because they are at a greater or lesser distance than what's in focus.

In the other thread where some photographers posted examples of MFDB images that exhibited, in their opinion, a heightened sense of 3-dimensionality, I recall most of those images had a fairly shallow DoF. For example, a model sitting in the middle of a road with the foregrounf and background clearly OoF, or a close-up of a face with the eyeball and eye lashes razor sharp but the cheek surrounding the eye slightly OoF.

I would suggest what's happening here is, we know from experience that the distance between an eye and the surrounding cheek is very small, in fact so small that it could be in the same plane depending on the angle of the shot. But we also know that areas that are OoF must be at a different distance. If the surrounding skin were as sharp as the eyeball, it would not be so clear as to whether or not that area of skin was in the same plane as the eyeball. The fact that the surrounding skin is OoF gives the brain the clues it needs for a heightened sense of 3-D.

In the 2 photos of the charcoal drawings in the beginning of this thread, the hands in the foreground are noticeably OoF as well as the back of the head and parts of the clothing, although these differences between what's in focus and what's not in focus have been diminished as a result of downsizing and jpeg compression, which is why these photographic reproductions do not have quite the same feel of heightened 3-D as the original drawings.

You must all be familiar with the phenomenon of a large print that has a discernible shallowness of DoF ceasing to have that same shallowness when reduced to postcard size.

If we get back to this concept of the primitive native who has never witnessed large distances, we might speculate that a similarly remote tribe who was not familiar with the photograph, would not appreciate any heightened sense of 3-D from images with OoF foregrounds and backgrounds.

Hope this is now as clear to you as it is to me   .
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« Last Edit: November 12, 2007, 03:04:27 am by jing q »
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tomholland

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The 3-D Effect
« Reply #41 on: November 12, 2007, 03:08:22 am »

Please take your tech weenie and the meaning of life argument off-line or to someplace that welcomes it -- there are many places that love this sort of crap. This is a place to discuss medium format digital backs and nothing else.
« Last Edit: November 12, 2007, 03:13:27 am by tomholland »
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Ray

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The 3-D Effect
« Reply #42 on: November 12, 2007, 07:52:51 am »

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Please take your tech weenie and the meaning of life argument off-line or to someplace that welcomes it -- there are many places that love this sort of crap. This is a place to discuss medium format digital backs and nothing else.
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Well, that's simply not true. Did you ever take the trouble to read the heading for this section of the forum. I'll spell it out for you.

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Medium Format Digital Backs and Photography

This forum is intended exclusively for the discussion of medium format digital backs and related topics. Users of all brands and models are welcome, as are all photographers interested in learning more about this equipment.

This thread I started is related to two other recent threads in this section which you will find at [a href=\"http://luminous-landscape.com/forum/index.php?showtopic=19964]http://luminous-landscape.com/forum/index....showtopic=19964[/url] and http://luminous-landscape.com/forum/index....showtopic=19198 .

The subject being discussed relates a certain quality of 3-dimensionality that digital backs can produce, in the opinion of owners of MFDBs, which smaller formats can't. But there seems to be some uncertainty as to the reasons for this perception. Does it really result from the larger sensor of the MFDB or is it entirely due lighting, shade and DoF etc?

Now I happen to be interested in such topics and I suspect a few others who read this forum are too. The fact that you are not, greatly surprises me. And since you are not interested, why spoil it for others and be obnoxious?
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Jonathan Wienke

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The 3-D Effect
« Reply #43 on: November 12, 2007, 08:10:02 am »

Add me to the list of people interested in the ways 3-dimensionality is conveyed through 2-dimensional renderings.
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Ray

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The 3-D Effect
« Reply #44 on: November 12, 2007, 08:38:51 am »

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regarding your points about large prints losing their shallowness, interestingly as I had mentioned before, one of the big prints I made really took on a very dimensional feel only when printed big, and I noticed the effect wasn't due to the depth of field (yes it was shallower...but not extremely), but the detailed tonalities between colours on the people's faces and clothing that created a sense of volume in each object.
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Isn't the reason for this greater detail of tonality on faces and clothing on the large print due to the fact you have not thrown information away by downsizing the image for a smaller print. (Well, perhaps that's putting it backwards. The reason may also be you used a high resolution MFDB). You say there was a slight shallowness of DoF but not extreme. A slight shallowness of DoF is exactly the sort of thing that disappears when you downsize. If the shallowness is significant, it's probably still noticeable even on a postcard size print, but not as great of course as on a large print.

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Take a look at some hyperrealistic sculptures (which are 3 dimensional in the first place...and yet they can seem more "dimensional" than reality)

Yes, I believe you. And those two charcoal drawings I copied looked like photos but with an extra sense of 3-dimensionality which unfortunately hasn't come through in the copying and downscaling.
« Last Edit: November 12, 2007, 09:02:36 am by Ray »
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jjj

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The 3-D Effect
« Reply #45 on: November 12, 2007, 01:02:44 pm »

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That's a good question. Why do people often prefer the original to a copy? If the copy is indistinguishable from the original, why would some people still prefer the original? Is it just the money factor? If a lady wears a diamond necklace which is a good copy of the real necklace which is kept in the safe, and if the copy is so good that no-one but a jewelery expert with magnifying glass can tell the difference, would the lady feel or notice any change if she accidentally wore the real necklace thinking that she was wearing the copy?
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This reminds me of a B+W print I saw in a gallery, that I had seen reproduced in several photography magazines. I liked the picture, but when I saw the print in the flesh it was not just a good image, but a very moving image. It was a war photograph BTW. There was a flattening in the quality of the image during reproduction which caused it to lose something vital.
Same goes for Gregory Crewdson's work, I'd seen it in books but seeing the large prints was quite different.  No different I guess to seeing an A4 print of a 15' painting or watching an epic movie on the small screen. And not even big TV's are not a patch on the cinema screen for impact.
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Tradition is the Backbone of the Spinele
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