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Old 04-15-2013, 12:10 PM   #1
feed3r
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Question Limitations of (photo-realistic) rendering

Hi guys!

I'm in need of your profound knowledge as I'm writing my thesis about photo-realistic still image creation right now. My question to you is rather simple yet needs a detailled explanation:

Is there any effect, we're not able to create due to the lack of features (rendering-/shading-wise) that we are given by today's state-of-the-art 3d packages? Or in other words: Is it possible to create any effect as long as you put enough (shading-)effort into it?

Right now I'm analysing different images and its use of rendering-techniques (Fresnel, SSS, MLT etc.) and I'm confronted with this question. I know, that most of our techniques are to some extend only faking real behaviour of light (as it would take an infinite time to calculate light). So my question kind of touches two topics:
1. Physically correct calculations of real life effects
2. Visually plausible representation (which is more important to me - imho users/viewers don't care much about 'physical correctness' as long as it looks realistic)

I need you to be questioning the term "photo-realistic". Imho there's only very few images that can be called (quite ) photo-realistic, yet everyone's considering every third image to be photo-realistic.

Thanks a lot!

Julian
 
Old 04-15-2013, 12:35 PM   #2
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Quote:
Originally Posted by feed3r
I need you to be questioning the term "photo-realistic". Imho there's only very few images that can be called (quite ) photo-realistic, yet everyone's considering every third image to be photo-realistic.



Theres a ton of Photoreal VFX work out there. You dont notice it...but thats kinda the point.

http://www.stargatestudios.net is one of the leaders, and honestly how they do half the stuff they do, I have no idea.

As for surfaces we cant do? Skin is always being worked on, but honestly I've seen some incredible stuff in recent years-but I think it will always be the 'benchmark' for realistic shaders.
 
Old 04-15-2013, 12:58 PM   #3
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Thanks for your answer pyke! I guess, i forgot to mention, that I focus my thesis on still images and visualisations. You are right, that there's a lot of realistic VFX stuff out there. I really don't want to start a discussion about VFX versus still images, but imho VFX benefits from its extensive use of post-work and motion blur, which makes it less suitable for me to compare shading-/rendering-features. (Though the VFX industry brings up tons of high-end shaders, I know.)
 
Old 04-15-2013, 01:05 PM   #4
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I dont think I've seen any totally realistic slime or viscera yet. Most creatures, monsters look too clean.
 
Old 04-15-2013, 01:18 PM   #5
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I imagine fluffy things would be hard to create. Sponge, cake, the middle of bread, you get the idea.
 
Old 04-15-2013, 01:30 PM   #6
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I've never tried it, but I would imagine a toilet paper roll simulation would be difficult.
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Old 04-15-2013, 02:12 PM   #7
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Nothing is impossible if you have the money to develop it. But then you would have to weight that off against filming something in camera.
 
Old 04-15-2013, 03:40 PM   #8
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Quote:
Originally Posted by feed3r
Thanks for your answer pyke! I guess, i forgot to mention, that I focus my thesis on still images and visualisations. You are right, that there's a lot of realistic VFX stuff out there. I really don't want to start a discussion about VFX versus still images, but imho VFX benefits from its extensive use of post-work and motion blur, which makes it less suitable for me to compare shading-/rendering-features. (Though the VFX industry brings up tons of high-end shaders, I know.)

Ironically the fact that something is a still image makes it a *hell* of a lot easier to 'fix' or at least aesthetically more pleasing with say Photoshop just because it doesn't need to move. You can render 80% of what you want and do the rest with paint if that is a preferred work-flow.

I've never done a lot of realistic rendering for print. But I have been increadibly impressed with some lookdev stills in pipelines I've worked on.
And the luster goes away as soon as I've seen the same thing animated.
It can be awesomely animated but never quite *real* once its in a sequence.

For stills I can only suggest an easy thing to get 'wrong' are eyes.
But I'm having a hard time finding something thats 'nearly impossible'
to get right without movement being *the* difference maker.
 
Old 04-15-2013, 04:42 PM   #9
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Quote:
Originally Posted by circusboy
ca
Ironically the fact that something is a still image makes it a *hell* of a lot easier to 'fix' or at least aesthetically more pleasing with say Photoshop just because it doesn't need to move. You can render 80% of what you want and do the rest with paint if that is a preferred work-flow.


You're right, circusboy. And of course: Most of the things that come with animation, humanoid or not, make it more challenging. But my question aims towards rendering/-shading-techniques only, "in-camera" - if you will.

A toilet paper roll I find quite challenging, too. Layering many "thin surfaces" (treated with e.g. the vray-2-sided-material) really close on top of each other feels different from the usual SSS-effect but are hard to achieve with the just mentioned 2-sided-material.
 
Old 04-15-2013, 04:50 PM   #10
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It's kind of in the middle if you ask me. Theres 2 parts to this really;

First I work mostly for print and photorealistic is a wavy term, "we want a glass perfume bottle, but please paint out all the refractions, even out the shadows, put in on a seamless white, and get rid of anything that dosent look clean..." So in the end it looks just like every other magazine shot you've ever seen. It's clean but not really photorealistic.

Secondly we often have to match a photo reference or backplate. After it's rendered out A LOT of post work and painting in photoshop goes into it, then in the end it looks "photo realistic". The thing is though, that nothing ever comes right out of a render engine with perfect photorealism. There is always compositing, and in my case painting. So then are we really capable of rendering something realistic? I think the answer is no, we rendering something that gives a good starting point, but a lot work work goes into from that point. If you want to consider compositing and painting part of rendering than Yes, but ultimately the computer is not spitting out a perfect image from your 3d package.
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Old 04-15-2013, 06:12 PM   #11
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Quote:
Originally Posted by Panupat
I imagine fluffy things would be hard to create. Sponge, cake, the middle of bread, you get the idea.


I agree. Foods can be very hard to render. Because they can require a variety of shaders that are needed to make them look convincing. Such as volumetric, scattering, and other raytracing effects. Soups are a good example of this.
 
Old 04-15-2013, 11:22 PM   #12
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Ooohhh scrambled eggs! Never seen it done! Even more difficult would be fried tomato and eggs.
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Old 04-15-2013, 11:49 PM   #13
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Quote:
Originally Posted by teruchan
Ooohhh scrambled eggs! Never seen it done! Even more difficult would be fried tomato and eggs.

I imagine a big part of not having seen it is that the moment all you need is a still, 5 bucks of ingredients and a half decent camera are a lot cheaper than doing it in 3D

I'm with mr Bob, doubly so if we talk stills. There is nothing I have ever seen that couldn't be done to complete photorealism, it's just a matter of money and time, and whether it was convenient or not, that you have or haven't seen some things done more than others.

BTW, Sponges are actually not that hard to do volumetrically. Rather easy in fact.
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Old 04-16-2013, 07:25 AM   #14
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Thumbs up

Thanks for your valuable response, guys. I'm exactly on your page.

In my thesis I'm especially looking at the technical side of today's (in-camera) rendering techniques. That's why it's totally fine to say, that non-post-images are not photorealistic at the time. Yet I'm wondering, what is missing then.

Let's bringt Maxwell Render to the table: They claim to be absolutely realistic, having features, that are usually done in post, such as lens effects, like chromatic abberation, bloom etc.

What's technically missing then (given the reasonable assumptions, that you can't spent unlimited time and money on a project and regardless of our artistic capabilities and the fact, that realistic is only subjective perception - I know, this will always be an effect, but as I said, I'm especially looking the technical side)?
 
Old 04-16-2013, 09:56 AM   #15
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Another vote for food, especially when you're working with substances that blend into each other. We had to work on animated closeups of dumplings in creamy soup a while ago. Displaying dumplings soaking up the soup to various degrees was quite challenging. Was probably due to the fact that we had no accurate enough way of controlling the changes in substance volumetrically. If it hadn't been for some compositing work I doubt the results would have looked as realistic.

As far as I know Maxwell offers some kind of material blending for meshed fluids, which probably helps to some degree. But I doubt that would be enough for some more complex food scenes.

Grüße aus Stuttgart!
 
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