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Motiejus Jakštys 2021-05-19 22:57:47 +03:00 committed by Motiejus Jakštys
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mj-msc.tex
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@ -6,11 +6,11 @@
\usepackage{a4wide}
\usepackage [autostyle, english=american]{csquotes}
\MakeOuterQuote{"}
\usepackage[maxbibnames=99,style=authoryear]{biblatex}
\usepackage[maxbibnames=99,style=numeric,sorting=none]{biblatex}
\addbibresource{bib.bib}
\usepackage[pdfusetitle]{hyperref}
\usepackage{enumitem}
\usepackage[toc,page,title]{appendix}
\addbibresource{bib.bib}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{gensymb}
@ -24,11 +24,9 @@
\input{vars.inc}
\newcommand{\onpage}[1]{\ref{#1} on page~\pageref{#1}}
\newcommand{\DP}{Douglas \& Peucker}
\newcommand{\VW}{Visvalingam--Whyatt}
\newcommand{\WM}{Wang--M{\"u}ller}
\newcommand{\MYTITLE}{Cartographic Generalization of Lines using free software (example of rivers)}
\newcommand{\MYAUTHOR}{Motiejus Jakštys}
@ -123,24 +121,25 @@ The "classical" ones are {\DP} and {\VW}.
\subsection{{\DP} and {\VW}}
\cite{douglas1973algorithms} and \cite{visvalingam1993line} are "classical"
line generalization computer graphics algorithms. They are relatively simple to
implement, require few runtime resources. Both of them accept only a single
parameter, based on desired scale of the map, which makes them very simple to
adjust for different scales.
{\DP} \cite{douglas1973algorithms} and {\VW} \cite{visvalingam1993line} are
"classical" line generalization computer graphics algorithms. They are
relatively simple to implement, require few runtime resources. Both of them
accept only a single parameter, based on desired scale of the map, which makes
them very simple to adjust for different scales.
Both algorithms are part of PostGIS, a free-software GIS suite:
\begin{itemize}
\item \cite{douglas1973algorithms} via
\item {\DP} via
\href{https://postgis.net/docs/ST_Simplify.html}{PostGIS Simplify}.
\item \cite{visvalingam1993line} via
\item {\VW} via
\href{https://postgis.net/docs/ST_SimplifyVW.html}{PostGIS SimplifyVW}.
\end{itemize}
Since both algorithms produce jagged output lines, it is worthwhile to process
those through a widely available \cite{chaikin1974algorithm} smoothing
algorithm via \href{https://postgis.net/docs/ST_ChaikinSmoothing.html}{PostGIS
those through a widely available Chaikin's line smoothing
algorithm \cite{chaikin1974algorithm} via
\href{https://postgis.net/docs/ST_ChaikinSmoothing.html}{PostGIS
ChaikinSmoothing}.
Even though {\DP} and {\VW} are simple to understand and computationally
@ -234,9 +233,9 @@ and the implementation.
\centering
\begin{tabular}{|c|c|c|c|c|c|c|}
\hline
Degrees & $0^\circ$ & $30^\circ$ & $45^\circ$ & $90^\circ$ & $180^\circ$ & $360^\circ$ \\
Degrees & $30^\circ$ & $45^\circ$ & $90^\circ$ & $180^\circ$ & $360^\circ$ \\
\hline
Radians & $0$ & $\nicefrac{\pi}{6}$ & $\nicefrac{\pi}{4}$ & $\nicefrac{\pi}{2}$ & $\pi$ & $2\pi$ \\
Radians & $\nicefrac{\pi}{6}$ & $\nicefrac{\pi}{4}$ & $\nicefrac{\pi}{2}$ & $\pi$ & $2\pi$ \\
\hline
\end{tabular}
\caption{Popular degree and radian values}
@ -269,10 +268,10 @@ unexpected bugs have snug in while modifying the algorithm.
\section{Description of the implementation}
Like alluded in section~\onpage{sec:introduction}, \cite{wang1998line} paper
skims over certain details, which are important to implement the algorithm.
This section goes through each algorithm stage, illustrating the intermediate
steps and explaining the author's desiderata for a more detailed description.
Like alluded in section~\onpage{sec:introduction}, {\WM} paper skims over
certain details, which are important to implement the algorithm. This section
goes through each algorithm stage, illustrating the intermediate steps and
explaining the author's desiderata for a more detailed description.
Illustrations of the following sections are extracted from the automated test
cases, which were written during the algorithm implementation (as discussed in