Mental note: shadowmap-space filters

A thought I often had (and chances are many people did and will) about shadows is that some processing in shadowmap space could help for a variety of effects. This goes from blurring ideas (variance shadow maps and variants) to the idea of augmenting shadowmaps (e.g. with distance to-nearest-occluder information).

I've always discarded these ideas though (in the back of my mind) because my experience with current-gen told me that often (cascaded) shadowmaps are bandwidth-bound. To a degree that even some caching schemes (rendering every other frame, or tiling a huge virtual shadowmap) fail because the cost of re-blitting the cache in the shadowmap can exceed the cost of re-rendering.

So you really don't want to do per-texel processing on them, and it's better instead to work in screenspace, either by splatting shadows in a deferred buffer and blurring, or by doing expensive PCF only in penumbra areas and so on (i.e. with min/max shadowmap mipmaps to compute trivial-in shadow and trivial-out shadow cases and branch).

It seems though that lately caching schemes are becoming practical (probably they are already for some games on current-gen, by no mean my experience on the matter in Space Marines can be representative of all graphic loads).

In these cases it seems logical to evaluate the possibility of moving more and more processing in shadowmap space. 

Then again, a reminder that a great metaheuristic for graphics is to try to reframe the same problem in a different space (screen, light, UV, local, world... pixel/vertex/object...)

Just a thought.

Never Again in Graphics: Unforgivable graphic curses.

Well known, zero cost things that still are ignored too often.

Do them. On -any- platform, even mobile.

Please.

• Lack of self-occlusion. Pre-compute aperture cones on every mesh and bend the normalmap normals, change specular occlusion maps and roughness to fit the aperture cone. The only case where this doesn't apply is for animated models (i.e. characters), but even there baking in "t-pose" isn't silly (makes total sense for faces for example), maybe with some hand-authored adjustments.
• Non-premultiplied alpha.
• Wrong Alpha-key mipmaps computed via box (or regular image) filters.
• Specular aliasing (i.e. not using Toksvig or similar methods).
• Analytic, constant emission point/spot lights.
• Halos around DOF filters. Weight your samples! Maybe only on low-end mobile, if you just do a blur and blend, it might be understandable that you can't access the depth buffer to compute the weights during the blur...
• Cartoon-shading-like SSAO edges. Weight your samples! Even if for some reason you have to do SSAO over the final image (baaaad), at least color it, use some non-linear blending! Ah, and skew that f*cking SSAO "up", most light comes from sky or ceiling, skewing the filter upwards (shadows downwards) is more realistic than having them around objects. AND don't multiply it on top of the final shading! If you have to do so (because you don't have a full depth prepass) at least do some better blending than straight multiply!
• 2D Water ripples on meshes. This is the poster child of all the effects that can be done, but not quite right. Either you can do something -well enough- or -do not do it-. Tone it down! Find alternatives. Look at reference footage!
• Color channel clamping (after lighting), i.e. lack of tonemapping. Basic Reinhard is cheap, even on shaders on "current-gen" (if you're forced to output to a 8bit buffer... and don't care that alpha won't blend "right").
• Simple depth-based fog. At least have a ground! And change the fog based on sun dot view. Even if it's constant per frame, computed on the CPU.

If you can think of more that should go in the list, use the comments section!

Shit people say: graphics have "peaked"

If you think that rendering has peaked, it's probably good. Probably it means you're not too old and haven't lived through the history of 3d graphics, where at every step people thought that it couldn't get better. Or you're too old and don't remember anymore...

Really, if I think of myself on my 486sx playing Tie Fighter back then, shit couldn't get any better. And I remember Rebel Assault, the first game I bought when I had my first CD-rom reader. And so on and on (and no, I didn't play only Star Wars games, but at the time LucasArts was among the companies made all must-buy titles... until the 360 I've always been a "computer" gamer, nowadays I play only on consoles).

But but but, these new consoles launched and people aren't that "wowed" right? That surely means something. We peaked, it happened.

I mean, surely it is not that when the 360 and later PS3 came out games weren't looking incredibly much better than what we had on ps2, right? (if you don't follow the links, you won't get the sarcasm...). And certainly, certainly the PS2 launch titles (was touted as more powerful than a SGI... remember?) it blew late PS1 titles right out of the water. I mean, it wasn't just more resolution.

Maybe it's lack of imagination. As I wrote, I was the same, many times as I player I failed to imagine how it could get better. To a degree I think it's because video-game graphics, like all forms of art, "speak" to the people of their time, first and foremost. Even if some art might be "timeless" that doesn't imply that its meaning remains constant over time, it's really a cultural, aesthetic matter which evolves over time.
Now I take a different route, which I encourage to try. Just go out, walk. See the world, the days, the nights. Maybe pick up a camera... How does it feel? To me, working to improve rendering, it's amazing. Amazing! I could spend hours walking around and looking in awe and envy at the world we can't yet quite capture in games.
Now think if you could -play- reality, tell stories in it. Wouldn't it be a quite powerful device? Won't it be the foundation for a great game?

Stephen Shore, one of the masters of American color photography

Let me be explicit though, I'm not saying that realism is the only way, in the end we want to evoke emotions, and that can be done in a variety of ways, I'm well aware. Sometimes it's better to illustrate and let the brain fill in the blanks, emotions are tricky. Take that incredible masterpiece that is Kentucky Route Zero which manages to use flat-shaded vector graphics and still feel more real than many "photo-realistic" games. 
It's truly a game that every rendering engineer (and every other person too) should play, to be reminded of what are the goals we are working for: pushing the right buttons in the brain and trick it to remember or replay emotions it experienced in the real world. 
Other examples you might be more accustomed to are Call of Duty (most of them) and Red Dead Redemption, two games that are (even if it's very questionable actually) not as technically accomplished as some of the competition but manage to evoke and atmosphere that most other titles don't even come close to.

At the end of the day, photo-realism is just a "shortcut", as if we have something that spits realistic images for every angle and every lighting, it's easier to focus on the art, the same way that it's cheaper to film a movie rather than hand paint every frame. It's a set of constraints, a way of reducing the parameters space from the extreme of painting literally every pixel every frame to more and more procedural models where we "automate" a lot of the visual output and allow creativity to operate on the variables left free to tuning (i.e. lighting, cinematography and so on). 
It is -a- set of constraints, not the -only- one. It's just a matter of familiarity, as we're trying to fool our brains into firing the right combinations of neurons, it makes some sense to start with something that is recognizable as real, as our lives and experiences are drawn from real world. But different arguments could be made (i.e. that abstraction helps this process of recollection), this would be the topic of a different discussion. If your artists are more comfortable working in different frameworks there is a case to be made for alternatives, but when even Pixar agrees that physics are a good infrastructure for productive creativity then you have a quite strong "proof" that it's indeed a good starting point.

Diminishing returns... It's nonsense. Not that it doesn't exist as a phenomenon, but we are still far from being there in terms of effort vs quality, and there are many ways to mitigate it in asset production as well (money vs content, which will then hopefully relate to money). 
As I said, everyday I come back home from the office, and every day (or so) I'm amazed at the world (I'm in Vancouver, it's pretty here) and how far we still have to go to simulate all this... No, it's not going to be VR the next step (Oculus is amazing, truly, even if I'm still skeptical about a thing you have to wear and for which we have no good controls), there is still a lot to do on a 2d screen, both in rendering algorithms and in pure processing power. 
Yes we need more polygons please. Yes we need more resolution. And then more power on top of that to be able to simulate physics, and free our artists from the shackles of needing to eyeball parameters and hand-painted maps and so on...

And I don't even buy the fact that rendering is "ahead" and other things "lag" behind. How do you even make the comparison?

AI is "behind" because people in games are not as smart as humans? Well, quite unfair to the field, I mean, trying to make something look like a photo, versus something behave like a human, seems to be a bit easier to me.

Maybe you could say that animation is behind because well, things look much worse in motion than they do when they are static. But, not only part of that is a rendering problem, but it just says exactly that, things in motion are "harder" than static things, it doesn't mean that "motion" lags behind as a field...
Maybe you can say we implemented more novel techniques in rendering than we did in other fields, animation didn't change that much over they years, rendering changed more. I'm not entirely sure it's true, and I'm not entirely sure it means that much anyways, but yes, maybe we had more investment or some games did, to be more precise.

Anyhow, we still suck. We are just now beginning to understand the basics of what colors are, of what materials are, how light works. Measure, capture, model... We're so ignorant still. Not to mention on the technical side. Pathetic. We don't even know what to do with most of the hardware yet (compute shaders? for what?).

There could be an argument that spending more money on rendering is not worth it - because spending them on something else now gets us more bang for the buck, which is a variation of the "rendering is ahead" reasoning that doesn't hinge on actually measuring what is ahead of what. I could consider that, but really the reason for it is just that it's harder to disprove. But on the other hand, it's also completely random! 
Did we measure this? That would be actually fascinating! Can we devise an experiment where we can turn a "rendering" know and an "animation" or "gameplay" know and see what are people most sensitive to? I doubt it, seriously, but it would be awesome.
Maybe we could do some market research and come up with metrics that say that people buy more games if they have better animation over rendering, but... I think rendering actually markets better (that's why companies name and promote their rendering engines, but not their animation ones).

Lastly, you could say, it's better to spend money somewhere else just because it seems that rendering is expensive and maybe the same money just pays so much more innovation somewhere else. Maybe. This still needs ways of measuring things that can't be measured, but really the thing is some people are scared that asset costs will still go up and up. Not really "rendering" costs, but "art" costs. Well -rendering- actually is the way to -lower- art costs. 
No rendering technique is good if it doesn't serve art better, and unfortunately even there we still suck... We are mostly making art the same way we always did, triangles, UVs, manually splitting objects, creating LODs, grouping objects and so on. It's really sad, and really another reason to be optimistic about how much still we have to do in the future.

Now, I don't want to sound like I'm saying, I'm a rendering guy, my field is more relevant and all the money should go to it. Not at all! And actually I'm passionate of a lot of things, animation for example is fascinating as well... and who knows, maybe down the line I'll do stuff that it's completely different than what I'm doing today... I'm just annoyed that people say thing that are not really based in facts (and as we're at it, let's also dispel the myth that hardware progress is slowing down...).

Cheers.

Never again: point lights

Distant, point, spotlight, am I right? Or maybe you can merge point and spot into an uberlight. No.

Have you ever actually seen a point-light in the real world? It's very rare, isn't it? Even bare-bulbs don't exactly project uniformly in the hemisphere...

If you're working with a baked-GI solution that might not affect you much, in the end you can start with a point, construct a light fixture around it and have GI take care of that. But even in the baked world you'll have analytic lights most often. In deferred, it's even worse. How many games show "blobs" of light due to points being placed around? Too many!

With directional and spots we can circumvent the issue somehow by adding "cookies", 2d projected textures. With points we could use cube textures, but in practice I've seen too many games not doing it (authoring also could be simpler than hand-painting cubes...)

During Fight Night (boxing game) one little feature we had was light from camera flashes, which was interesting as you could clearly see (for a fraction of a second) the pattern they made on the canvas (journalists are all around the ring) and there it was the first time I noticed how much point lights suck.

The solution was easy, really, I created a mix of a point and distant light, which gave a nice directional gradient to the flash without a cone shape of spots. You could think of the light as being a point and the "directional" part being a function that made the emission non constant on the hemisphere. 

It's a multiply-add. Do it. Now!

Minimum-effort "directional" point

Another little trick that I employed (which is quite different) is to "mix" point and directional in terms of the incoming light normal on the shaded point (biasing point normals towards a direction), at the time an attempt to create lights that were "area" somehow, softer than pure points. But that was really a hack...

Nowadays you might have heard of IES lights (see this and this for example), which are light emission profiles often measured by light manufacturers (which can be converted to cubemaps, by the way). 

I would argue -against- them. I mean sure, if you're going towards a cubemap based solution sure, have that as an option, but IES are really meaningful if you have to go out in the real world and buy a light to match a rendering you did of an architectural piece, if you are modeling fantasy worlds there is no reason to make your artists go through a catalog of light fixtures just to find something that looks interesting. What is the right IES for a pointlight inside a barrel set on fire?

A more complicated function

A good authoring tool would be imho just a freehand curve, that gets baked into a simple 1d texture (in realtime, please, let your artists experiment interactively), mapped with light direction dot (light position-shaded point).
If you want to be adventurous, you can take a tangent vector for the light and add a second dot product and lookup. And add the ability of coloring the light as well, a lot of lights have non-constant colors as well, go around and have a look (i.e. direct light vs light reflected out of the fixture or passing through semi-transparent material...).

1d lookups are actually -better- than a cubemap cookies, because if you see in real world example many fixtures generate very sharp discontinuities in the light output, which are harder (require much more resolution) to capture in a cubemap...

Exercise left for the reader: bake the light profile approximating a GI solution, automatically adapting it to the enviroment the light was "dropped" in...

Enhance this!

Don't you hate when people have strong critiques towards a thing, but it happens that it's just that they don't know enough about it? Well, I don't, because then I think of how many times in my youth (and let's say only then) I did the same...

Regardless, today I happen to have a bit of time and I saw yet another post laughing at how stupid the "image enhance" trick used in movies and TV series is, and so you get this nerdrage against nerdrage...

Now think a second about this. Who do you think it's right? C.S.I., which is a huge TV series using arguably some of the best writers and consultants, or the random dude on the net? Do you think they don't know how realistic any of the techniques they use is?

Do you think they don't actually and very carefully thread between real science and fiction to deliver a mix that is comprehensible and entertains their audience, telling a story while keeping it grounded in actual techniques used in the field? Don't you think -they- know better, and the result was very consciously constructed? 
Well, ok sometimes producers just don't care, they want to tell a story, not write a documentary, but more often than not that's not the case.

The same goes of course for anything, really, especially when something is successful, makes a lot of money, has a lot of money behind, you should always bias yourself towards being humble and assuming the professionals making said thing -know better-.

Now, back to the "image enhance" trick. It turns out it is real science. It's called "super-resolution" and it's a deep field with a lot (really, a lot!) of research and techniques behind it.

It's actually common nowadays as well, chances are that if your TV has some sort of SD2HD conversion, well that is super-resolution in action (and even more surprising are all the techniques that can reconstruct depth from a single image, which also ship in many TVs, the kind of models they came up with for that are crazy!).

The scenarios presented in movies are actually -quite- realistic even if the details are fictionalized. True, the interface to these programs won't look like that, maybe they won't be real-time and surely they won't be able to "zoom" in "hundreds" of times, but they surely can help and surely are used. 

That is to me a reasonable compromise between fiction and reality, as certainly you can and will use computers to get a legible nameplate for a video that is too low-resolution for the naked eye, or match an otherwise unreadable face against a database of suspects and so on, probably not in quite as glamorous and simple way as the movies show, but fundamentally the idea is sound (and I'm quite sure, used in the real world).

It is a non-realistic representation of a very realistic scenario, which is the best that good fiction should try to achieve, going further is silly. Or are you going to argue that a movie is crap because at night for example you can't really see as clearly as they show, or because they don't let a DNA test take weeks and an investigation several years?

When it comes to videos we can use techniques known as "multiple image" super-resolution, registering (aligning) multiple images (frames in this case, i.e. optical flow), and merging the results, which do work quite well. Also, most fictionalized super-resolution enhances focus on faces or nameplates, which are both much easier to super-resolve because we can "hint" the algorithm with a statistical model (a-priori) which helps tremendously to guide the "hallucination".

And even if hallucinating detail might not hold in a court (the stronger the a-priori model, the more it will generate plausible results but by no means always reliable), it might be very well be used as a hint to direct the investigations (I've never seen a case where it was used in courts, always to try to identify a potential suspect or a nameplate, both cases where having a strong probability, even if it's far from certainty, are realistic).

So, bottom line is, if you think these guys are "stuuuuupid", well then you might want to think twice. Here are some random-ish links (starting points... google scholar for references and so on if you're interested... I couldn't even find many of my favorite ones right now) to the science of super-resolution:

• An example with nameplates, showing extreme reconstructions
• Another blind deconvolution paper, seems great on car plates
• Hallucinating faces
• An opensource implementation of video-based SR and a commercial multiple-image SR implementation
• Video to video SR, and another one...
• Classic paper of single-image super-resolution, trying to find similarities in the same image (to a degree, similar to fractal methods for image compression, which can indeed be used also for SR). Less strong results as the algorithm makes no prior assumptions.
• Multiple cameras (i.e. surveilance)
• More and more...
• An overview of commercial software used in forensics

It would take many pages only to survey the general ideas in the field. Don't limit your imagination... Computer science is more amazing than you might think... We reconstruct environments from multiple cameras, or even sweeping video... can capture light in flight, we can read somebody's heartbeat from video, fucking use lasers to see around corners and yes, even take some hints about an environment from corneas...

And by the way, don't bitch about Gravity, try enjoy the narrative instead. You might live a happier life :)