Master's Thesis - Studierstube Augmented Reality Project - Graz ...

2.2 Advanced Graphics Processing
2.2.1 The Latest Available Graphics Hardware
After more than 15 years of usage, the basic vertex processing pipeline has been superseded
by a new architecture. The classic programmable pipeline has several disadvantages.
An unbalanced processor load for example will be an effect of much more pixel
shader instructions than vertex shader instructions. Building one Arithmetic-Logic
Unit (ALU) per vertex and fragment processing will result in an overloaded and an unchallenged
unit. Furthermore it was nearly impossible to reprocess already calculated
results in the pipeline. These drawbacks have been resolved by the G8x processor
used on GeForce 8x cards. In this architecture at most 128 stream processors (GeForce
8800 GTX 1 ) are able to process both vertex and fragment geometry instructions. Theoretically,
employing a ”Thread-Processor” for this should enable each ALU to operate
at full capacity.
(a) Block diagram of the GeForce 8x architecture. (b) Block diagram of the GeForece 6x architecture.
Figure 2.16: Comparison of Nvidia’s G8x (a) and G6x (b) processor architecture from
[Nvidia2006] and [Pharr2005]. Remarkable is that the G8x stream processors are now
able to do both, which was still separated on the G6x series.
Due to increasing programmable requirements of graphics hardware, Nvidia decided
to design the architecture around the processor as illustrated in figure 2.16(a).
Consequently, it is now possible to overcome the two main drawbacks described above
- ”real loops” and ”balanced load”. However, although the implementation of this
work in chapter 5 has been performed on a GeForce 8800 system, mainly the hardware
1 released in November 2006,
30