Posted: June 16, 2000
Written by: Tuan "Solace" Nguyen

GTS: GigaTexel Shader

GTS stands for "GigaTexel Shader". As the name suggests, some new features have been added to the GeForce 256, but we'll get to that later...

What is a GigaTexel? It is one billion filtered textured pixels. But the GeForce 2 GTS's powerhouse doesn't stop there -- it delivers up to a full 1.6 billion texels/sec; more than three times that of the GeForce 256. But the speed increase isn't the only upgrade that the GeForce 256 received. The term "shader" should have indicated a new lighting feature as part of the T&L system. The shading engine enables per-pixel shading and lighting.

NSR: NVIDIA Shading Rasterizer

Likely one of the most significant feature for the GeForce 2 GTS is the inclusion of what NVIDIA calls the NVIDIA Shading Rasterizer or the NSR. What is the NSR? We can't tell you what it is, you just have to s-- okay, enough Matrix stuff. But as a matter of fact, it is a matrix. It is a one by seven matrix. The NSR is a radically new rendering engine. It can juggle 7 pixels in a single pass applying advanced per-pixel shading effects.

What is per-pixel shading? It's a method of applying special rendering effects... per pixel. It allows material and real world effects to be applied individually to a pixel for more accuracy and intensity. Per-pixel shading will redefine the visual look and feel of imagery for PC graphics. Per-pixel shading has long been used in film production to create a more realistic and lifelike appearance for computer generated imagery. If you've seen Toy Story, you'll definitely remember Buzz Light-year. Remember the translucent reflection on Buzz's helmet? How the environment and light streaks reflected off the glass but also let the image underneath show through? That was done with per-pixel shading. Until now, it wasn't practical to use per-pixel shading on a PC because of the intense power and processing requirements needed. Sure, you could have done that in 3D Studio but could you have done it in real-time? Could the effect be applied to an entire frame at high resolution in 1/60th of a second? Not until now.

Per-pixel shading is useful for simulating natural phenomena and accurate surface attributes such as fur, cloth, metals, glass, rock, and other highly detailed surfaces.

Traditionally, effects were done on an entire triangle and sometimes an entire texture using a technique called interpolation. Special effects were done using calculations based on the vertices of the triangle and interpolating the entire area from the vertices. The end result is a generalized visual appearance… like an estimate or approximation of the final image. The benefit of using interpolation is it is fast to apply. But, the downside to it is that with large triangles, the resulting image contains artifacts, which degrades overall image accuracy and quality.

Next Page