This is a rather general question: what defines the realism in a game? All I can think about are texture quality and higher polygon count. I'm no professional designer, so I'm not sure what goes into a scene that makes it look real(other than the stated examples). I've just recently started 3D programming, thus I won't be making the next Battlefield anytime soon, this question is solely asked for my curiosity.

Note: I'm not asking for code or language-specific examples, just the general variables that differentiate a game that looks unrealistic and a game that looks realistic, such as a lighting system.

(If this has been asked before, please reference the link to the page).

A realistic lightning model helps a ton. Possibly more than texture size and polygon count.

In the real world light bounces and propagates in ways we are still only faking in games. No amount of extra triangles on a Coke machine model or extra texture detail in a wall will add that indirect bounce of red from the Coke machine onto the wall around it.

There's a lot of subtle things in the way light works in the real world that we can't all really notice, but our brains can still tell when it's not quite right in a simulation.

Effort directed towards better approximations of lightning, both via offline and real-time processes, can help quite a bit.

Yup, an accurate lighting system will be huge towards achieving realism. In addition to that you'll want your artists to be experienced with these types of physically based lighting systems so you can't create "impossible" materials or lighting setups.

Offline rendering methods such as path tracers already can achieve photorealism, but the techniques used there are way too expensive to apply in a real-time context.

Agreed -- Lighting.

Tim Sweeney of Epic Games and a graphs wiz every bit as good as Carmack--if not better--roughly lumps generational lines of rendering advancements as to how many bounces of light they simulate. In raycasters like Doom, light bounced just once off of a surface of the world directly to a pixel on your screen and nothing intervened in it -- light didn't come from anywhere in the world, it was just an ambient value, ever-present, constant, radiating in all directions evenly. In the first generation of polygon games like Quake or Unreal, light "bounced" twice -- light affecting a particular surface had a single origin in the world and each origin could have different properties, an ambient lighting factor continued to stand in for all the indirect bounces; pre-baked light-maps helped color-in the illusion of localized lighting and occlusion. For a long time, lighting advances came by increasing the number of lights in a scene, not increasing the number of bounces -- Even through Doom 3 was more lights, not more bounces. Modern games of today simulate ~3 bounces -- IIRC, the ambient light factor bounces off of one surface, picking up its properties, propagates that to a nearby surface, and finally the sum of this and the localized, two-bounce lighting to your eye. The coming generation--maybe today's bleeding edge--should make a good run at subsurface scattering.

Adaptive animation is another of the current frontiers that builds on realism. After that, probably AI/Behavior that results in more than a simple choice between pre-canned responses that are blended at best -- something more natural than that will be needed to cross the uncanny valley once we reach realistic-appearing humans in real-time..

A parallel advancement has been Physically-based lighting, which gives materials a logical consistency like you see in the real world. In the past, materials were often bespoke and could have their knobs tuned to wildly different values to achieve an appearance consistent with the scene as a whole.

Realistic is a very misleading word the way we know it. When people say I want a game to look "realistic", what they really want is to have it look like it was filmed by a Holywood studio with special lighting setups (which may vary for different shots), makeup, particular hair styles that always highlight nice places and cover the not so pretty places, special lenses, and particular camera angles with a particular camera movement.

You know the phrase "even the girl from the fashion magazine doesn't look like the fashion model in the magazine" ? Same applies to "realistic" graphics, because people expect game's graphics to look like people in a magazine, TV shows, and movies. Which isn't realistic at all.

Therefore to look realistic we have to mimic what they do: Once we figure out the math stuff (proper BRDF, use HDR, Depth of field, wind effects, noise for a shaky camera effect), we need to setup lighting as in movie production (i.e. 3-point lighting is very popular), have the characters perform fashion-model-like walks for females, movie-like poses (3 point landing, anyone?), account for the 12 principles of animation, place the camera in strategic places, have camera shots change at the right times, have the depth of field focus what's important and leave what's unimportant out of focus.

Of course, high resolution textures, high polycount, motion capture and global illumination helps a lot; but it will only get you so far.

And of course, all of these "rules" can be broken. If you know what you're doing and know when to break them, it still looks good. When you don't, it looks crap. Just like crappy movies or your grandma's pictures (no offense to your grandma!).

These are a nice read:

- http://artisaverb.info/GDC2013.html
- http://artisaverb.info/QuantifyingBeauty.html

I think that.... lightning illuminates something. And that we pay too much atention to the lightning itself only, omiting what we illuminate. Normal map is a picture! A constant set of data (an identical thing under angles is identical thing to human observer).

Seeing all the time the very same thing under angles, while it would have been changed radicaly in reality!

This is blocking the actual interactive realistic video experience. We need to have volatile surfaces, normals, etc. Games can produce realistic stills, but if you move in them- Ups!

Physics. I think a game with good simulated physics is makes a game look realistic.

Many things go into making a game look realistic. Basically, the Art and level design teams trying to do everything they can to make things look realistic, and having enough time and resources to get somewhat close to that goal, is what makes a game look realistic.

Art direction, backed up with good tech and plenty of resources.

Define realistic.

Most of what people call "realistic" in games today is just "looks like in the movies I have seen". Some games lately tried to make explosions and ballistic effects as well as sounds more realistic... players whined a tank gun now sounds like a toy.

Yet when you hear a tank gun from some meters away, that is actually how it sounds. Its the hollywood movies that got it wrong, and those tend to form the opinion of people on "realism" because most people in the western world are fortunate enough of never having heard the sound of a tank gun being fired, or having seen an explosion of a hand grenade.

So really, "realism" is kinda misleading.

As to what helps give modern games a "realistic" feel today, I agree with everything being said in this thread until now. Physically based lighting, some postprocessing effects (as long as we do not have the rendering power for better GI, SSAO is pretty important to give objects that "weight" that makes them look real), as well as enough polygons to hide the fact that you are looking at polygon objects. The last thing is of course depending on the chose point of view... if you are only seeing characters from meters away in an isometric view, that 100k polygon character with fully articulated face and wrinkle maps most probably is pure overkill and just eats system resources for little to no gain.

Something in specific to characters. Good facial animations, newer technology like wrinkle maps, and good rigs that allow body parts to deform realistically (like muscles) are essential for character closeups.

I second the AI point though. The most realistic looking game is going to break down if your enemies are acting like dumb robots with faulty programming. The more realistic everything looks, the more off a too simple AI will feel.