Hello tomato.
And you're right. Taking a simple 3d model and animating it will indeed result in smooth animation. But it will not always result in realistic, or pleasing animation. Smoothness isn't always good. A keyframed 6 frame 2d animation might work quite better than a 25 frame even node-3d animation. A human hand, for example, contracts somewhat and changes shape according to the direction of the action, has muscles inside, the flesh folds, it suffers the effect of gravity and all that. Like tomato said. Obviously, when you have a bone animation using a simple cylinder-connected-to-cylinder arm, none of this is there. And little by little it adds up to really wooden and unnatural motion. Even the supposed best attempts at 2dish quality through 3d ( appleseed comes to mind ) this is really noticable and unpleasant. Now, of course, if you are a brilliant 3d animator, you will sit down and code in muscles for biceps, abs and balls and all that, but if you're accomplished enough to do all that, chances are you could do an animation in 2d if you wanted, so emulating 2d through 3d is pointless. MrColossal showed us a link to a fast-motion video of a guy going through all the steps of creating a 3d monster model, and animating him and all that. It was a revelation in that he was so good that he sat down and sculptured the model before remaking it in 3d. He didn't stop there. He made a sceleton for it, and muscles over it, arrrgh. To be a *great* 3d artist, you have to be *that* good. Good 3d is not a shortcut, and it's not easier than good 2d. Bad 3d is just faster.
And you're right. Taking a simple 3d model and animating it will indeed result in smooth animation. But it will not always result in realistic, or pleasing animation. Smoothness isn't always good. A keyframed 6 frame 2d animation might work quite better than a 25 frame even node-3d animation. A human hand, for example, contracts somewhat and changes shape according to the direction of the action, has muscles inside, the flesh folds, it suffers the effect of gravity and all that. Like tomato said. Obviously, when you have a bone animation using a simple cylinder-connected-to-cylinder arm, none of this is there. And little by little it adds up to really wooden and unnatural motion. Even the supposed best attempts at 2dish quality through 3d ( appleseed comes to mind ) this is really noticable and unpleasant. Now, of course, if you are a brilliant 3d animator, you will sit down and code in muscles for biceps, abs and balls and all that, but if you're accomplished enough to do all that, chances are you could do an animation in 2d if you wanted, so emulating 2d through 3d is pointless. MrColossal showed us a link to a fast-motion video of a guy going through all the steps of creating a 3d monster model, and animating him and all that. It was a revelation in that he was so good that he sat down and sculptured the model before remaking it in 3d. He didn't stop there. He made a sceleton for it, and muscles over it, arrrgh. To be a *great* 3d artist, you have to be *that* good. Good 3d is not a shortcut, and it's not easier than good 2d. Bad 3d is just faster.