X-Git-Url: https://git.ucc.asn.au/?p=ipdf%2Fsam.git;a=blobdiff_plain;f=chapters%2FBackground_Spline.tex;h=d54ef10f596405b0dec5c7658ee9dc2b27fe6f54;hp=91244e4a8b3dce7cd1ae090cb44a48b1f0618cce;hb=0d7e6aa4d2966020240ea5b5f2a824502f271eaa;hpb=3b509bbb92dc136e78e681973ca9ba364fa7be20

diff --git a/chapters/Background_Spline.tex b/chapters/Background_Spline.tex
index 91244e4..d54ef10 100644
--- a/chapters/Background_Spline.tex
+++ b/chapters/Background_Spline.tex
@@ -10,7 +10,7 @@ Splines may be rasterised by sampling of $y(x)$ at a number of points $x_i$ and
 There are many different ways to define a spline.One approach is to specify ``knots'' on the curve and choosing a fixed $n$ ($n = 3$ for ``cubic'' splines) solve for the cooefficients to generate polynomials passing through the points. Alternatively, special polynomials may be defined using ``control'' points which themselves are not part of the curve; these are convenient for graphical based editors.\end{co B{\'e}zier splines are the most straight forward way to define a curve in the standards considered in Section \ref{Document Representations}. A spline defined from two cubic B{\'e}ziers is shown in Figure \ref{spline.pdf}
 \end{comment}
 
-Cubic and Quadratic B{\'e}zier Splines are used to define curved paths in the PostScript\cite{plrm}, PDF\cite{pdfref17} and SVG\cite{svg2011-1.1} standards which we will discuss in Section \ref{Document Representations}.  Cubic B{\'e}ziers are also used to define vector fonts for rendering text in these standards and the \TeX typesetting language \cite{knuth1983metafont, knuth1984texbook}. The usefulness of B{\'e}zier curves was realised by Pierre B{\'e}zier who used them in the 1960s for the computer aided design of automobile bodies\cite{bezier1986apersonal}. 
+Cubic and Quadratic B{\'e}zier Splines are used to define curved paths in the PostScript\cite{plrm}, PDF\cite{pdfref17} and SVG\cite{svg2011-1.1} standards which we will discuss in Section \ref{Document Representations}.  Cubic B{\'e}ziers are also used to define vector fonts for rendering text in these standards and the {\TeX}  typesetting language \cite{knuth1983metafont, knuth1984texbook}. Although he did not derive the mathematics, the usefulness of B{\'e}zier curves was realised by Pierre B{\'e}zier who used them in the 1960s for the computer aided design of automobile bodies\cite{bezier1986apersonal}. 
 
 A B{\'e}zier Curve of degree $n$ is defined by $n$ ``control points'' $\left\{P_0, ... P_n\right\}$. 
 Points $P(t) = (x(t), y(t))$ along the curve are defined by:
@@ -26,13 +26,13 @@ From these definitions it should be apparent that in all cases, $P(0) = P_0$ and
 
 Algorithms for rendering B{\'e}zier's may simply sample $P(t)$ for suffiently many values of $t$ --- enough so that the spacing between successive points is always less than one pixel distance. Alternately, a smaller number of points may be sampled with the resulting points connected by straight lines using one of the algorithms discussed in Section \ref{Straight Lines}.
 
-De Casteljau's algorithm of 1959 is often used for approximating B{\'e}ziers\cite{computergraphics2, knuth1983metafont}. This algorithm subdivides the original $n$ control points $\left\{P_0, ... P_n\right\}$ into $2n$ points $\left\{Q_0, ... Q_n\right\}$ and $\left\{R_0, ... R_n\right\}$; when iterated, the produced points will converge to $P(t)$. As a tensor equation this subdivision can be expressed as:
+De Casteljau's algorithm of 1959 is often used for approximating B{\'e}ziers\cite{computergraphics2, knuth1983metafont}. This algorithm subdivides the original $n$ control points $\left\{P_0, ... P_n\right\}$ into $2n$ points $\left\{Q_0, ... Q_n\right\}$ and $\left\{R_0, ... R_n\right\}$; when iterated, the produced points will converge to $P(t)$. As a tensor equation this subdivision can be expressed as\cite{goldman_thefractal}:
 \begin{align}
 	Q_i = \left(\frac{\left(^n_j\right)}{2^j}\right) P_i &\text{ and }	R_i = \left(\frac{\left(^{n-j}_{n-k}\right)}{2^{n-j}}\right) P_i
 \end{align}
 
 
-In much of the literature it is taken as trivial that it is only necessary to specify the control points of a B{\'e}zier in order to be able to render it at any level of detail\cite{knuth1983metafont, computergraphics2}. Recently, Goldman presented an argument that B{\'e}zier's could be considered as fractal in nature, because the De Casteljau algorithm may be modified to be expressed the polynomial $P(t)$ as the result of iterated function system\cite{goldman_thefractal}. If this argument is correct, any primitive that can be described soley in terms of B{\'e}zier Curves may also be considered as fractal in nature. Ideally all these primitives may be rendered at any level of detail or ``zoom'' desired; however, computation of the pixel locations of the curve will be subject to the precision limits of the numerical representation which is used; we discuss these issues in Section \ref{}.
+In much of the literature it is taken as trivial that it is only necessary to specify the control points of a B{\'e}zier in order to be able to render it at any level of detail\cite{knuth1983metafont, computergraphics2}. Recently, Goldman presented an argument that B{\'e}zier's could be considered as fractal in nature, because the De Casteljau algorithm may be modified to be expressed the polynomial $P(t)$ as the result of iterated function system\cite{goldman_thefractal}. If this argument is correct, any primitive that can be described soley in terms of B{\'e}zier Curves may also be considered as fractal in nature. Ideally all these primitives may be rendered at any level of detail or ``zoom'' desired; however, computation of the pixel locations of the curve will be subject to the precision limits of the numerical representation which is used; we discuss these issues in Section \ref{Number Representations}.
 
 
 \begin{figure}[H]