Changeset 277 for trunk/VUT/doc/SciReport/introduction.tex
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trunk/VUT/doc/SciReport/introduction.tex
r273 r277 1 1 \chapter{Introduction}%\chapter 2 2 3 \label{chap:overview} 4 \label{chap:classes} 5 6 This chapter provides introduction to visibility problems and 7 algorithms for computer graphics. In particular it presents a taxonomy 8 of visibility problems and algorithms. We discuss typical visibility 9 problems encountered in computer graphics including their relation to 10 the presented taxonomy. Finally, we classify the later described 11 visibility tools according to the presented taxonomy. 12 3 \label{chap:introduction} 13 4 14 5 \section{Structure of the report} 6 7 The report consists of two introductory chapters, which provide a 8 theoretical background for description of the algorithms, and three 9 chapters dealing with the actual visibility algorithms. 10 11 This chapter provides an introduction to visibility by using a 12 taxonomy of visibility problems and algorithms. The taxonomy is used 13 to classify the later described visibility 14 algorithms. Chapter~\ref{chap:analysis} provides an analysis of 15 visibility in 2D and 3D polygonal scenes. This analysis also includes 16 formal description of visibility using \plucker coordinates of 17 lines. \plucker coordinates are exploited later in algorithms for 18 mutual visibility verification (Chapter~\ref{chap:mutual}). 19 20 Chapter~\ref{chap:online} describes a visibility culling algorithm 21 used to implement the online visibility culling module. This 22 algorithm can be used accelerate rendering of fully dynamic scenes 23 using recent graphics hardware. Chapter~\ref{chap:sampling} 24 describes global visibility sampling algorithm which forms a core of 25 the PVS computation module. This chapter also describes view space 26 partitioning algorithms used in close relation with the PVS 27 computation. Finally, Chapter~\ref{chap:mutual} describes mutual 28 visibility verification algorithms, which are used by the PVS 29 computation module to generate the final solution for precomputed 30 visibility. 31 15 32 16 33 … … 127 144 we obtain a vector that represents the same line $l$. More details 128 145 about this singularity-free mapping will be discussed in 129 Chapter~\ref{chap: vfr2d}.146 Chapter~\ref{chap:analysis}. 130 147 131 148 … … 207 224 208 225 Although the \plucker coordinates need more coefficients they have no 209 singularity and preserve some linearities: lines intersecting a set of 210 lines in 3D correspond to an intersection of 5D hyperplanes. More details211 on \plucker coordinates will be discussed in212 Chapter s~\ref{chap:vfr25d} and~\ref{chap:vfr3d} where they are used to213 solve the from-region visibility problem.226 singularity and preserve some linearities: lines intersecting a set of 227 lines in 3D correspond to an intersection of 5D hyperplanes. More 228 details on \plucker coordinates will be discussed in 229 Chapter~\ref{chap:analysis} and Chapter~\ref{chap:mutual} where they 230 are used to solve the from-region visibility problem. 214 231 215 232 To sum up: In 3D there are four degrees of freedom in the … … 627 644 the nature of the given problem and it should assist in finding 628 645 relationships between visibility problems and algorithms in different 629 application areas. The tools address the following classes of646 application areas. The algorithms address the following classes of 630 647 visibility problems: 631 648 … … 641 658 discussed important steps in the design of a visibility algorithm that 642 659 should also assist in understanding the quality of a visibility 643 algorithm. According to the classification the tools address 644 algorithms with the following properties: 660 algorithm. According to the classification the visibility algorithms 661 described later in the report address algorithms with the following 662 properties: 645 663 646 664 \begin{itemize} 647 665 \item Domain: 648 666 \begin{itemize} 649 \item viewpoint (online culling tool),650 \item global visibility (global visibility sampling tool)651 \item polygon or polyhedron (mutual visibility tool)667 \item viewpoint (online visibility culling), 668 \item global visibility (global visibility sampling) 669 \item polygon or polyhedron (mutual visibility verification) 652 670 \end{itemize} 653 671 \item Scene restrictions (occluders): … … 671 689 \item Solution space: 672 690 \begin{itemize} 673 \item discrete (online culling tool, global visibility sampling tool, conservative and approximate algorithm from the mutual visibility tool)674 \item continuous (exact algorithm from mutual visibility tool)691 \item discrete (online visibility culling, global visibility sampling, conservative and approximate algorithm from the mutual visibility verification) 692 \item continuous (exact algorithm from mutual visibility verification) 675 693 \end{itemize} 676 \item Solution space data structures: viewport (online culling tool), ray stack (global visibility sampling tool, conservative and approximate algorithm from the mutual visibility tool), BSP tree (exact algorithm from the mutual visibility tool)694 \item Solution space data structures: viewport (online visibility culling), ray stack (global visibility sampling, conservative and approximate algorithm from the mutual visibility verification), BSP tree (exact algorithm from the mutual visibility verification) 677 695 \item Use of coherence of visibility: 678 696 \begin{itemize} 679 \item spatial coherence (all tools)680 \item temporal coherence (online culling tool)697 \item spatial coherence (all algorithms) 698 \item temporal coherence (online visibility culling) 681 699 \end{itemize} 682 \item Output sensitivity: expected in practice (all tools)683 \item Acceleration data structure: kD-tree (all tools)684 \item Use of graphics hardware: online culling tool700 \item Output sensitivity: expected in practice (all algorithms) 701 \item Acceleration data structure: kD-tree (all algorithms) 702 \item Use of graphics hardware: online visibility culling 685 703 \end{itemize} 686 704
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