FSAA Graphic Card Technology

In mid-2000, 3dfx sought to strike back at rival nVidia in the battle for supremacy in the graphics arena with its T-Buffer technology, unveiled on its Voodoo5 range of cards. The T-Buffer allows several key digital effects for improving photorealism in real-time 3D graphics rendering. Until now, these effects have not been available on consumer-level PCs at real-time frame rates. These include:

  • motion blur – to add a realistic blur to moving objects that are otherwise defined more sharply than they would be if they were real objects actually photographed on chemical film
  • depth of field – to add visual cues that help define the distance to each object in a scene by way of different levels of sharpness, or degrees of focus, at different depths, and, perhaps most importantly of all
  • full-screen anti-aliasing (FSAA).

Aliasing artefacts come in two forms: jaggies, or stairstepping of diagonal lines, and flashing or popping of very thin polygons. These are referred to as spatial artefacts because they occur because the scene being rendered is under sampled. Previously available only in professional visual simulation systems – such as military flight simulators – FSAA smoothes the jagged lines and eliminates the scintillating of very thin objects by taking many samples of the scene and blending them together. The result is a much smoother, far more realistic and pleasing image.

3dfx’s implementation of FSAA technology uses a technique call Rotated Grid Super Sampling (RGSS) to anti alias computer images. With RGSS, the image is drawn multiple times and the images are offset slightly to reduce the size of the jaggies on the edges of objects, virtually eliminating the visual artefacts that result from aliased images. The resulting image is claimed to be much more photo-realistic than FSAA images delivered by use the ordered grid super sampling (OGSS) technique.

What is so significant about FSAA is that it works straight out of the box – application software doesn’t need to be specially coded to make use of it. Users can configure the graphics card driver to use the amount of FSAA they wish: none, two samples or four samples. The greater the number of samples, the smoother the resulting image will appear.