Introduction

With the (commercial) availability of capable computer hardware in the mid-70's many computer applications, which are quite essential for today's engineers (and not only for them), were born - for example

• CAD/CAM
• Computer Tomography
• Computer games

Many of them involves the processing of data which could no longer be represented in textual form for human interaction as it had been usual for the number-crunchers of the first generation. An architect using CAD for constructing a building maybe works on a data set representing the building by millions of polygons combined with attributes specifying i.e. their material; a doctor may have a volumetric dataset of

$$1024\times 1024\times 512 = 536.87\cdot 10^6 \hbox{ voxel } \approx 1\hbox{ GByte of memory usage}$$

produced by a CT scan. Hollywood's productions are crying for special effects to make the impossible possible. Last but not least the aspect of computer games: during the early 90's their focus changed from 2D-games (jump'n run etc.) to 3D games (o.k., the change had a name: Doom - although it wasn't a real 3D game at all...). IMHO it's not wrong to say that the requirements of 3D computer games have been the pushing force behind the majority of personal computer improvements, i.e. the change from the ISA system bus over EISA to today's PCI system bus architecture, the creation of a high speed node (AGP slot) into this bus architecture for overcoming the bottleneck ISA-bus between CPU/memory and the graphic adapter, the improvements of memory access & technology and the various CPU operation code set extensions (3Dnow!, ISSE and what may follow...).

These demands lead to a new kind of computer science: the computer graphic branch. We'll discuss only the 3D-related section here, for more information in general see [Fel88]. Furthermore we focus on algorithm for photo-realistic rendering here.