1 - A Technical Overview  |  2 - Computer Games  |  3 - The Human Eye

30 Frames per Second vs. 60 Frames per Second

Games on the Computer

This is the second toughest part of this article. TV and Movies are easy to understand, and the technology behind it is also easy to understand. Computers and the way games are projected to us is a lot more complex (the most complex is the actual physiology /neuro-ethology of the visual system). First off, the hardware used for visualization (namely the monitor) is a very fine piece of equipment. It has a very small dot pitch (distance between phosphors) and the phosphors themselves are very fine, so we can get exquisite detail. We set the refresh rates at over 72 Hz for comfort (flicker free). This makes a very nice canvas to display information on, unfortunately because it is so fine it can greatly magnify flaws in the output of a video card. We will get into refresh in the section on the human eye. Let us start with how a scene or frame is set up by the computer. Each frame is put together in the frame buffer of the video card and is then sent out through the RAMDAC to the monitor. That part is very easy, nothing complex there (except the actual setup of the frame). Now each frame is perfectly rendered and sent to the monitor. It looks good on the screen, but there is something missing when that action gets fast. So far, programmers have been unable to make motion blur in these scenes. When a game runs at 30 fps, you are getting 30 perfectly rendered scenes. This does not fool the eye one bit. There is no motion blur, so the transition from frame to frame is not as smooth as in movies. 3dfx put out a demo that runs half the screen at 30 fps, and the other half at 60 fps. There is a definite difference between the two scenes, with the 60 fps looking much better and smoother than the 30 fps. The lack of motion blur with current rendering techniques is a huge setback for smooth playback. Even if you could put motion blur into games, it really is not a good idea whatsoever. We live in an analog world, and in doing so, we receive information continuously. We do not perceive the world through frames. In games, motion blur would cause the game to behave erratically. An example would be playing a game like Quake II, if there was motion blur used, there would be problems calculating the exact position of an object, so it would be really tough to hit something with your weapon. With motion blur in a game, the object in question would not really exist in any of the places where the "blur" is positioned. So we have perfectly drawn frames, so objects are always able to be calculated in set places in space. So how do you simulate motion blur in a video game? Easy, have games go at over 60 fps! Why? Read the section on the human eye. Variations in frame rate also contribute to games looking jerky. In any game, there is an average frame rate. Rates can be as high as the refresh rate of your monitor (70+), or it can go down in the 20's to 30's. This can really affect the visual quality of the game, and in fast moving ones can actually be detrimental to your gameplaying performance. One of the great ideas that came from the now defunct Talisman project at Microsoft was the ability to lock frame rates (so the rate goes neither above or below a certain framerate). In the next series of graphics cards, we may see this go into effect.

1 - A Technical Overview  |  2 - Computer Games  |  3 - The Human Eye