GeForce FX 5900 Ultra in Detail Continued
- Intellisample HCT
nVidia incorporates the new Intellisample HCT. HCT stands for High Compression Technology which tells the Intellisample is a new compression algorithm. The following is taken from the nVidia handbook on the new GeForce FX 5900 Ultra:
NVIDIA Intellisample HCT delivers the next step in performance and visual quality, compressing color, texture, and z data. Performance gains can be seen in all applications, especially at high resolutions with antialiasing. This new technology allows for up to a 50-percent increase in compression efficiency in these modes, and delivers unprecedented visual quality for resolutions up to 1600 × 1280.
NVIDIA Intellisample HCT includes a "quality" mode that delivers true anisotropic filtering and that allows programmers to achieve unmatched visual clarity for every portion of the scene, even difficult areas representing surfaces viewed from a sharp angle or from a distance.
- More on Ultra Shadow
Ultrashadow is nVidia's name for a new routine that is employed to help accelerate shadow volumes. Doom 3 will be the first game out to take out a huge amount on a video card due to the shadow level that it requires, here is what nVidia have to say:
Shaders are also used to create sophisticated shadows for enhanced realism. The new NVIDIA UltraShadow technology accelerates the complex computations for lighting source and object interactions. For details on this patent-pending NVIDIA innovation, please refer to the NVIDIA GeForce FX: UltraShadow Technology paper at http://www.nvidia.com.
UltraShadow gives programmers the ability to calculate shadows much more quickly by eliminating unnecessary areas from consideration. With UltraShadow, programmers can define a bounded portion of the scene (often called depth bounds) that limits calculations of lighting source effects to objects within a specified area. (See Figure 2.) By limiting calculations to the area most affected by a light source, the overall shadow generation process can be greatly accelerated. Programmers can fine-tune shadows within critical regions, create incredible visualizations that effectively mimic reality, and still achieve awesome performance for fast-action games. The accelerated shadow generation can also free up time that can be allocated to other sophisticated but time-consuming effects.
Because stenciled shadow volumes require no texturing or color updates, the hardware "doubles up" the rendering horsepower to generate stenciled shadow volumes at speeds of up to double the standard pixel-processing rate. Other graphics solutions have to render stenciled shadow volumes in two passes. UltraShadow accomplishes the shadow volume rendering in a single pass, reducing CPU overhead and improving GPU performance. The NVIDIA approach also interoperates with NVIDIA Intellisample high-resolution compression technology (HCT) to make sure that shadow edges are properly antialiased. The GeForce FX 5900 GPUs maintain the stencil information on a sub-pixel basis, ensuring that shadow edges are antialiased rather than "blocky" or "jaggy."