Realtime Ray Tracing and Interactive Global Illumination - Scientific ...

4 Chapter 1: Introduction
either remove some fundamental limitations of triangle rasterization – which
most researchers deem impossible – or to accelerate ray tracing to the point
where it allows for realtime applications.
For more than a decade now, different researchers have argued that due
to several inherent advantages of ray tracing – coupled with ever-increasing
availability of hardware resources and ever-increasing user demands – ray
tracing performance should eventually overtake triangle rasterization [Kajiya86,
Teller98]. Though these claims are yet unfulfilled for almost two decades, it
seems that with some of the recently ongoing developments this scenario is
finally taking on shape. In the long term, realtime ray tracing should allow
for both higher quality and higher performance than any other kind of
rendering technology.
1.1 Outline of This Thesis
This thesis is structured into three independent parts, reporting on an introduction
to interactive ray tracing, the RTRT/OpenRT interactive ray tracing
system, and the Instant Global Illumination method, respectively.
Part I starts by introducing the ray tracing method in Chapter 2, and
gives a brief survey of ray tracing acceleration techniques in Section 3. Chapter
4 then discusses the benefits of using ray tracing for interactive applications,
and addresses the question why in the near future ray tracing is likely
to play a larger role in interactive graphics. Part I then ends with an overview
over the most important currently ongoing approaches towards realizing realtime
ray tracing on different kinds of hardware platforms, which include
various software systems, GPU-based ray tracing, and special purpose ray
tracing hardware.
The main part of this thesis (Part II) then describes one of these approaches
(the RTRT/OpenRT software realtime ray tracing system) in more
detail: Chapter 6 starts with a detailed discussion of the issues to be kept
in mind when designing a realtime ray tracing system on todays CPUs, and
outlines the most fundamental design guidelines of the RTRT core. Chapter
7 then in detail describes the technical aspects of the RTRT core, namely
fast ray/triangle intersection, fast BSP traversal, the efficient use of SIMD
instructions, and high-quality BSP construction. Chapter 8 then shows how
these fast core algorithms can be efficiently parallelized on small clusters
of commodity PCs, resulting in near-linear scalability and high ray tracing
performance without the need for sophisticated hardware resources. Following
this, Chapters 9 and 10 discuss some advanced ray tracing issues, like