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This is an unpopular opinion, but nobody knows how to make anything look real. The quicker you accept and internalize this, the easier it is to dive into graphi

This is an unpopular opinion, but nobody knows how to make anything look real. The quicker you accept and internalize this, the easier it is to dive into graphics programming. It reveals graphics programming for what it is: A bag of tricks that mostly look good in certain constrained circumstances. When I first started out, I chased book after book looking for knowledge. "Someone must know how to make things look real, right? Everyone is talking so authoritatively on the topic." No, no one knows. There's no source of knowledge that represents the cutting edge of the field, because the cutting edge is whatever happens to look pretty good today. And that's mostly thanks to very good art, not very good techniques. Just dive in and start doing geometric puzzles. Look at it like a game, not like a quest for knowledge. If you have fun with it you'll go further than any book will take you.

miketuritzin 9y ago
From my experience this is very much true of the current state of real-time rendering (and there's nothing really wrong with that, because it's just not possible to run anything resembling physically accurate algorithms in real-time). However, in the world of offline rendering and raytracing, there has been considerable work on doing physically accurate rendering. Of course a lot of approximations are still made due to memory/CPU constraints, but it is a different world. "Physically Based Rendering" by Pharr and Humphreys is a good intro to this way of doing things.
- sillysaurus3 9y ago
  If that were true, we'd see the evidence in Hollywood. But nobody knows how to make a realistic fully-simulated video. The reason everyone believes that it's just around the corner is because those academics talk with authority on the topic, and the still frames look pretty convincing. But still frames are completely different from video -- the human visual system processes video differently. I've written about this before: https://news.ycombinator.com/item?id=13892671 https://news.ycombinator.com/item?id=13892671 https://news.ycombinator.com/item?id=12461883 https://news.ycombinator.com/item?id=12461883 https://news.ycombinator.com/item?id=13893305 https://news.ycombinator.com/item?id=13893305 The only technique that we know produces realistic video is if you mix actual, real footage with simulated content. That's very effective, but it's unsatisfying for obvious reasons. I think it hints at a way toward fully simulated realistic video, though.
  - miketuritzin 9y ago
    To me the most interesting thing is not just a fully-simulated video but a fully-simulated interactive scene using VR or AR, and that is obviously an even bigger challenge. I don't personally think that either of these objectives are even close to being just around the corner, but I do think we are moving toward them. I have no idea how many additional orders of magnitude in computing power would be necessary to create a convincing simulation. The journey in that direction is a fun challenge though, right? I did just read your previous posts, and it sounds like you have a pretty interesting history of working on all of this stuff.
dahart 9y ago
I love the motivation and message of this comment - to not worry and just dive in. But a few people most definitely do know how to make some very realistic graphics. So much so, that I guarantee you've seen some in movies that you didn't know was fake. I used to make CG movies, and I can't spot the best CG anymore. The trend in film rendering is, across the board, graduating from "tricks" that work to physically based processes, to whatever degree it is feasible. The setups are getting simpler, not more complex. The surface modeling, material modeling, color processing, lighting and rendering have all moved by leaps and bounds in last 10 years. It is is the process of shifting from art to physics, and the job of CG lighting technicians is becoming closer to the job of stage lighting technicians, because the lighting and rendering is physically based now. It's possible there are developments you don't know about. It's also possible you're suffering from evidence of Sturgeon's law and not seeing the top 10% clearly; there is plenty of crappy CG that doesn't look real, the vast majority of it doesn't look real. But the best of it is realistic and getting better every single year, and the people studying it do know some ways (and are currently adding more) to improve the realism when the computational power arrives.
- sillysaurus3 9y ago
  As I mentioned below, the only technique that produces effective results is if you mix actual, real footage with CG. It's true that people can't spot the CG in that situation, but that's different from the discussion of how to create fully-simulated realistic video. I'll give you a simple way to defeat any question of whether we know how to make something look real: What does it mean to multiply two colors? If you chase down the logic, the true answer is "It's meaningless. It just happens to be an approximation that looks good in most cases." But it has nothing to do with how light works in real life. Yet every engine multiplies colors because the alternative is too computationally expensive -- and it still wouldn't produce realistic results because we don't source our art from real life. Artists typically control the content, and any art-driven pipeline is doomed to look pretty good but not real.
  - dahart 9y ago
    > the only technique that produces effective results is if you mix actual, real footage with CG This isn't true. > I'll give you a simple way to defeat any question of whether we know how to make something look real: What does it mean to multiply two colors? If you chase down the logic, the true answer is "It's meaningless." It's not meaningless at all, it's a close approximation of light absorption that happens to be measurably and perceptually indistinguishable from the physical spectral absorption process, save for a few corner cases that are being worked on. If the result is 99.9% accurate physically, and 100% perceptually indistinguishable to humans, then it's a valid predictive physical model. It has everything to do with the result of what light does in real life, and if it didn't, we wouldn't be using it to approximate light. Your thinking here seems to back up my suggestion that you might have missed out on some of the recent developments. Subsurface scattering, for example, is modeling absorption more phyically, and replacing the simple multiplication with a simulation process, because we now have the computational power to do so. Your argument is attacking the non-simulation aspects of rendering without addressing whether a simulation that is simpler than real life is acceptable. If I can't tell the difference, does it count? Because I'm 100% certain that color multiplication is not the problem when it comes to CG not looking real.
ChuckMcM 9y ago
I can't judge the popularity aspect of it but "nobody knows how to make anything look real." assumes obviously that the goal is to make it "look real". There are so many interesting aspects of modern computer graphics that have nothing to do with rendering realism. My favorite is visualization, or using graphics to create a visualization of a process that is not visible normally like fluid dynamics. But there are lots of others. I think that if you start from the most featured APIs you end up jumping in with a hugely steep learning curve that really hinders learning. Starting from the basics, very simple OpenGL or WebGL rendering, learning the algebra behind projections so you can think about what you want to see, and then the notions of texturing and shading, all help get from not knowing anything to knowing something much more efficiently.
fsloth 9y ago
"This is an unpopular opinion, but nobody knows how to make anything look real." Unpopular? By whom? Computer graphics is a crafty bag of tricks sprinkled on top of very concrete linear algebra and computational geometry. That said, it's actually hard to create appealing images just in plain old photography, so anyone thinking computer graphics would facilitate any artistic aspects is in for disappointment. The math needs to work, but you need artistic talents to make anything look good/real.
dividuum 9y ago
> A bag of tricks that mostly look good in certain constrained circumstances. Yeah. Computer graphics is all smoke and mirrors... except smoke and mirrors, because those are difficult :-)
cmurf 9y ago
What looks good, what looks real, is actually an active area of psychophysics research in high-dynamic range image capture and rendering. The real world is high dynamic range, but human vision is much more limited, but also spacially variant and adaptive. So we get multiple optimized "snap shots" of a scene rendered in real time and mapped into what our brain considers one scene. Look toward high key high brightness area of a scene, retina gain function clamps down the iris closes and you get properly rendered details in those areas, look toward a tree shaded bench at a rock under that bench and iris opens, gain function increases and again the shadow details are rendered. Cameras are just starting to do this. But that's capture. It's still HDR. Now you have to re-render all of that if you're going to reproduce it on a lower dynamic range device like a computer display. There aren't that many HDR screens on the market yet but those are also coming, and it means we don't have to do that next stage re-rendering which is a lot more subjective and still actively researched why some renderings look real and others look cartoonish. And the same would be true for computer generated graphics rather than captures.

miketuritzin 9y ago

From my experience this is very much true of the current state of real-time rendering (and there's nothing really wrong with that, because it's just not possible to run anything resembling physically accurate algorithms in real-time). However, in the world of offline rendering and raytracing, there has been considerable work on doing physically accurate rendering. Of course a lot of approximations are still made due to memory/CPU constraints, but it is a different world. "Physically Based Rendering" by Pharr and Humphreys is a good intro to this way of doing things.

sillysaurus3 9y ago
If that were true, we'd see the evidence in Hollywood. But nobody knows how to make a realistic fully-simulated video. The reason everyone believes that it's just around the corner is because those academics talk with authority on the topic, and the still frames look pretty convincing. But still frames are completely different from video -- the human visual system processes video differently. I've written about this before: https://news.ycombinator.com/item?id=13892671 https://news.ycombinator.com/item?id=13892671 https://news.ycombinator.com/item?id=12461883 https://news.ycombinator.com/item?id=12461883 https://news.ycombinator.com/item?id=13893305 https://news.ycombinator.com/item?id=13893305 The only technique that we know produces realistic video is if you mix actual, real footage with simulated content. That's very effective, but it's unsatisfying for obvious reasons. I think it hints at a way toward fully simulated realistic video, though.
- miketuritzin 9y ago
  To me the most interesting thing is not just a fully-simulated video but a fully-simulated interactive scene using VR or AR, and that is obviously an even bigger challenge. I don't personally think that either of these objectives are even close to being just around the corner, but I do think we are moving toward them. I have no idea how many additional orders of magnitude in computing power would be necessary to create a convincing simulation. The journey in that direction is a fun challenge though, right? I did just read your previous posts, and it sounds like you have a pretty interesting history of working on all of this stuff.

dahart 9y ago

I love the motivation and message of this comment - to not worry and just dive in. But a few people most definitely do know how to make some very realistic graphics. So much so, that I guarantee you've seen some in movies that you didn't know was fake. I used to make CG movies, and I can't spot the best CG anymore. The trend in film rendering is, across the board, graduating from "tricks" that work to physically based processes, to whatever degree it is feasible. The setups are getting simpler, not more complex. The surface modeling, material modeling, color processing, lighting and rendering have all moved by leaps and bounds in last 10 years. It is is the process of shifting from art to physics, and the job of CG lighting technicians is becoming closer to the job of stage lighting technicians, because the lighting and rendering is physically based now. It's possible there are developments you don't know about. It's also possible you're suffering from evidence of Sturgeon's law and not seeing the top 10% clearly; there is plenty of crappy CG that doesn't look real, the vast majority of it doesn't look real. But the best of it is realistic and getting better every single year, and the people studying it do know some ways (and are currently adding more) to improve the realism when the computational power arrives.

sillysaurus3 9y ago
As I mentioned below, the only technique that produces effective results is if you mix actual, real footage with CG. It's true that people can't spot the CG in that situation, but that's different from the discussion of how to create fully-simulated realistic video. I'll give you a simple way to defeat any question of whether we know how to make something look real: What does it mean to multiply two colors? If you chase down the logic, the true answer is "It's meaningless. It just happens to be an approximation that looks good in most cases." But it has nothing to do with how light works in real life. Yet every engine multiplies colors because the alternative is too computationally expensive -- and it still wouldn't produce realistic results because we don't source our art from real life. Artists typically control the content, and any art-driven pipeline is doomed to look pretty good but not real.
- dahart 9y ago
  > the only technique that produces effective results is if you mix actual, real footage with CG This isn't true. > I'll give you a simple way to defeat any question of whether we know how to make something look real: What does it mean to multiply two colors? If you chase down the logic, the true answer is "It's meaningless." It's not meaningless at all, it's a close approximation of light absorption that happens to be measurably and perceptually indistinguishable from the physical spectral absorption process, save for a few corner cases that are being worked on. If the result is 99.9% accurate physically, and 100% perceptually indistinguishable to humans, then it's a valid predictive physical model. It has everything to do with the result of what light does in real life, and if it didn't, we wouldn't be using it to approximate light. Your thinking here seems to back up my suggestion that you might have missed out on some of the recent developments. Subsurface scattering, for example, is modeling absorption more phyically, and replacing the simple multiplication with a simulation process, because we now have the computational power to do so. Your argument is attacking the non-simulation aspects of rendering without addressing whether a simulation that is simpler than real life is acceptable. If I can't tell the difference, does it count? Because I'm 100% certain that color multiplication is not the problem when it comes to CG not looking real.

ChuckMcM 9y ago

I can't judge the popularity aspect of it but "nobody knows how to make anything look real." assumes obviously that the goal is to make it "look real". There are so many interesting aspects of modern computer graphics that have nothing to do with rendering realism. My favorite is visualization, or using graphics to create a visualization of a process that is not visible normally like fluid dynamics. But there are lots of others. I think that if you start from the most featured APIs you end up jumping in with a hugely steep learning curve that really hinders learning. Starting from the basics, very simple OpenGL or WebGL rendering, learning the algebra behind projections so you can think about what you want to see, and then the notions of texturing and shading, all help get from not knowing anything to knowing something much more efficiently.

fsloth 9y ago

"This is an unpopular opinion, but nobody knows how to make anything look real." Unpopular? By whom? Computer graphics is a crafty bag of tricks sprinkled on top of very concrete linear algebra and computational geometry. That said, it's actually hard to create appealing images just in plain old photography, so anyone thinking computer graphics would facilitate any artistic aspects is in for disappointment. The math needs to work, but you need artistic talents to make anything look good/real.

dividuum 9y ago

> A bag of tricks that mostly look good in certain constrained circumstances. Yeah. Computer graphics is all smoke and mirrors... except smoke and mirrors, because those are difficult :-)

cmurf 9y ago

What looks good, what looks real, is actually an active area of psychophysics research in high-dynamic range image capture and rendering. The real world is high dynamic range, but human vision is much more limited, but also spacially variant and adaptive. So we get multiple optimized "snap shots" of a scene rendered in real time and mapped into what our brain considers one scene. Look toward high key high brightness area of a scene, retina gain function clamps down the iris closes and you get properly rendered details in those areas, look toward a tree shaded bench at a rock under that bench and iris opens, gain function increases and again the shadow details are rendered. Cameras are just starting to do this. But that's capture. It's still HDR. Now you have to re-render all of that if you're going to reproduce it on a lower dynamic range device like a computer display. There aren't that many HDR screens on the market yet but those are also coming, and it means we don't have to do that next stage re-rendering which is a lot more subjective and still actively researched why some renderings look real and others look cartoonish. And the same would be true for computer generated graphics rather than captures.