What limits the level of graphic detail in a game? [closed]

Question

This question popped into my head after seeing some preview images for Halo 4.

What limits a games' graphic level?

(If this is the wrong place for this question, I understand)

Game series' like Halo have multiple installments that come out on the same system ie. Halo->Halo 2 on the XBOX, Halo 3->Halo 4 on the Xbox 360, and the sequel invariably looks MUCH better than its predecessor. When I see behind-the-scenes-type development videos, the game creators will talk about, "Oh, this character model has x-times the amount of polygons as the old one..." which I assume is what makes it look better. My question is, if the game system could have handled that many... objects (to my layman understanding)... on screen at the same time, why couldn't the original game look that good?

1.Where is the limitation? What changes from game to game?

2.What improves from game to game?

Answer 1

I think answer is pretty obvious. Given hardware is a constant, the only variable is software (i.e. the game).

1. Game changes :-).
2. Game engine is improved and optimized, assets quality is increased. Usually second version is improved version of the first. So not only developers don't need to do everything from the scratch, but also they know weak points which need to be improved, and have much more time to work on it. Game artists also have more time to improve graphics, etc.

Answer 2

Halo->Halo 2 on the XBOX, Halo 3->Halo 4 on the Xbox 360, and the sequel invariably looks MUCH better than its predecessor. When I see behind-the-scenes-type development videos, the game creators will talk about, "Oh, this character model has x-times the amount of polygons as the old one..." which I assume is what makes it look better.

Actually Halo 2 used fewer polygons for characters than Halo* which makes it an instructive example. A lot of people assume more polygons equals better graphics because it's an easy number to directly point to, but it's not hard to think of an example where no, more polygons isn't better:

Imagine a sphere comprised of a couple hundred polygons, and another sphere comprised of a couple thousand polygons. They're both just spheres.

Now imagine the first sphere is rendered with a specular map for shiny highlights and a normal map for subtle texture on its surface, while the second sphere is rendered with basic Garoud shading. So now which sphere looks better, the one with more polygons?

I'm not saying that polygon count doesn't matter at all, but rather it's just one of a whole complex set of factors that determines the look of your graphics. Textures matter a ton, lighting matters a ton, etc. The reason sequels on the same hardware look better is simply that the artists are getting more practiced at creating graphics for that hardware.

*A couple years before Halo came out I had a conversation where I argued that we needed better lighting rather than more polygons, and everyone else piled on to crucify me for criticizing their polycount dogma. After Halo 2 came out I wished I had a time machine to go back and say "I told you so!"

Answer 3

As Petr said, ditto. Well, it would be a long lecture to teach all that is involved. Performance of hardware and optimization/qualities of the engine used, play part of what is possible to render in given framerate.

But mere polygon cruching and processing power is not really enough to make what we will perceive as pleasant graphics. To clarify... Here's a good video on graphics vs aesthetics